From 81291afa3fe2ac6d859a8078fda914a4781280be Mon Sep 17 00:00:00 2001
From: Jeff Hostetler <jeffhost@microsoft.com>
Date: Fri, 21 Dec 2018 11:44:14 -0500
Subject: [PATCH 01/25] Revert "pack-objects: add trace2 regions"

This reverts commit d5c1e3b80b8806f596b0ba28d971f5d1922274ab.
---
 builtin/pack-objects.c | 12 +-----------
 1 file changed, 1 insertion(+), 11 deletions(-)

diff --git a/builtin/pack-objects.c b/builtin/pack-objects.c
index 5a87bb909f00e7..507d381153511d 100644
--- a/builtin/pack-objects.c
+++ b/builtin/pack-objects.c
@@ -33,7 +33,6 @@
 #include "object-store.h"
 #include "dir.h"
 #include "midx.h"
-#include "trace2.h"
 
 #define IN_PACK(obj) oe_in_pack(&to_pack, obj)
 #define SIZE(obj) oe_size(&to_pack, obj)
@@ -3479,7 +3478,6 @@ int cmd_pack_objects(int argc, const char **argv, const char *prefix)
 		}
 	}
 
-	trace2_region_enter("pack-objects", "enumerate-objects", the_repository);
 	prepare_packing_data(&to_pack);
 
 	if (progress)
@@ -3494,20 +3492,12 @@ int cmd_pack_objects(int argc, const char **argv, const char *prefix)
 	if (include_tag && nr_result)
 		for_each_ref(add_ref_tag, NULL);
 	stop_progress(&progress_state);
-	trace2_region_leave("pack-objects", "enumerate-objects", the_repository);
 
 	if (non_empty && !nr_result)
 		return 0;
-	if (nr_result) {
-		trace2_region_enter("pack-objects", "prepare-pack", the_repository);
+	if (nr_result)
 		prepare_pack(window, depth);
-		trace2_region_leave("pack-objects", "prepare-pack", the_repository);
-	}
-
-	trace2_region_enter("pack-objects", "write-pack-file", the_repository);
 	write_pack_file();
-	trace2_region_leave("pack-objects", "write-pack-file", the_repository);
-
 	if (progress)
 		fprintf_ln(stderr,
 			   _("Total %"PRIu32" (delta %"PRIu32"),"

From b837111feec001b37c77abefb1263b3d26bbbd0e Mon Sep 17 00:00:00 2001
From: Jeff Hostetler <jeffhost@microsoft.com>
Date: Fri, 21 Dec 2018 11:41:58 -0500
Subject: [PATCH 02/25] Revert "gvfs:trace2: add trace2 tracing around
 read_object_process"

This reverts commit e15d3e9795a2c4f28af1b78f4857bc3a1e14b4c0.
---
 sha1-file.c | 15 +++------------
 1 file changed, 3 insertions(+), 12 deletions(-)

diff --git a/sha1-file.c b/sha1-file.c
index 4f829e8c608db5..d0ea83fb1e3132 100644
--- a/sha1-file.c
+++ b/sha1-file.c
@@ -745,8 +745,6 @@ static int read_object_process(const struct object_id *oid)
 
 	start = getnanotime();
 
-	trace2_region_enter("subprocess", "read_object", the_repository);
-
 	if (!subprocess_map_initialized) {
 		subprocess_map_initialized = 1;
 		hashmap_init(&subprocess_map, (hashmap_cmp_fn)cmd2process_cmp,
@@ -763,16 +761,13 @@ static int read_object_process(const struct object_id *oid)
 		if (subprocess_start(&subprocess_map, &entry->subprocess, cmd,
 				     start_read_object_fn)) {
 			free(entry);
-			err = -1;
-			goto leave_region;
+			return -1;
 		}
 	}
 	process = &entry->subprocess.process;
 
-	if (!(CAP_GET & entry->supported_capabilities)) {
-		err = -1;
-		goto leave_region;
-	}
+	if (!(CAP_GET & entry->supported_capabilities))
+		return -1;
 
 	sigchain_push(SIGPIPE, SIG_IGN);
 
@@ -821,10 +816,6 @@ static int read_object_process(const struct object_id *oid)
 
 	trace_performance_since(start, "read_object_process");
 
-leave_region:
-	trace2_region_leave_printf("subprocess", "read_object", the_repository,
-				   "result %d", err);
-
 	return err;
 }
 

From 089a0c7e64450f5e41e29d1f060f6a98d003c9ff Mon Sep 17 00:00:00 2001
From: Jeff Hostetler <jeffhost@microsoft.com>
Date: Fri, 21 Dec 2018 11:42:19 -0500
Subject: [PATCH 03/25] Revert "gvfs:trace2: add region/data events for status
 deserialization"

This reverts commit c7f9cb3355cb0d802af7fb593f2b0e692caf672e.
---
 wt-status-deserialize.c | 23 +++--------------------
 1 file changed, 3 insertions(+), 20 deletions(-)

diff --git a/wt-status-deserialize.c b/wt-status-deserialize.c
index 8647ed3ab23cbb..23b2f69798bb8a 100644
--- a/wt-status-deserialize.c
+++ b/wt-status-deserialize.c
@@ -725,18 +725,15 @@ static int try_deserialize_read_from_file(const struct wt_status *cmd_s,
 					  enum wt_status_deserialize_wait dw,
 					  struct wt_status *des_s)
 {
-	int k = 0;
-	int limit;
+	int k, limit;
 	int result = DESERIALIZE_ERR;
 
 	/*
 	 * For "fail" or "no", try exactly once to read the status cache.
 	 * Return an error if the file is stale.
 	 */
-	if (dw == DESERIALIZE_WAIT__FAIL || dw == DESERIALIZE_WAIT__NO) {
-		result = try_deserialize_read_from_file_1(cmd_s, path, des_s);
-		goto done;
-	}
+	if (dw == DESERIALIZE_WAIT__FAIL || dw == DESERIALIZE_WAIT__NO)
+		return try_deserialize_read_from_file_1(cmd_s, path, des_s);
 
 	/*
 	 * Wait for the status cache file to refresh.  Wait duration can
@@ -761,12 +758,6 @@ static int try_deserialize_read_from_file(const struct wt_status *cmd_s,
 		sleep_millisec(100);
 	}
 
-done:
-	trace2_data_string("status", the_repository, "deserialize/path", path);
-	trace2_data_intmax("status", the_repository, "deserialize/polled", k);
-	trace2_data_string("status", the_repository, "deserialize/result",
-			   ((result == DESERIALIZE_OK) ? "ok" : "reject"));
-
 	trace_printf_key(&trace_deserialize,
 			 "wait polled=%d result=%d '%s'",
 			 k, result, path);
@@ -792,8 +783,6 @@ int wt_status_deserialize(const struct wt_status *cmd_s,
 	struct wt_status des_s;
 	int result;
 
-	trace2_region_enter("status", "deserialize", the_repository);
-
 	if (path && *path && strcmp(path, "0")) {
 		result = try_deserialize_read_from_file(cmd_s, path, dw, &des_s);
 	} else {
@@ -804,14 +793,8 @@ int wt_status_deserialize(const struct wt_status *cmd_s,
 		 * term, since we cannot read stdin multiple times.
 		 */
 		result = wt_deserialize_fd(cmd_s, &des_s, 0);
-
-		trace2_data_string("status", the_repository, "deserialize/path", "STDIN");
-		trace2_data_string("status", the_repository, "deserialize/result",
-				   ((result == DESERIALIZE_OK) ? "ok" : "reject"));
 	}
 
-	trace2_region_leave("status", "deserialize", the_repository);
-
 	if (result == DESERIALIZE_OK) {
 		wt_status_get_state(&des_s.state, des_s.branch &&
 				    !strcmp(des_s.branch, "HEAD"));

From eebf43af34fca1b5bd2c4b16b9479b325696e6d2 Mon Sep 17 00:00:00 2001
From: Jeff Hostetler <jeffhost@microsoft.com>
Date: Fri, 21 Dec 2018 11:42:28 -0500
Subject: [PATCH 04/25] Revert "trace2: instrument reading and writing the
 index"

This reverts commit 918f51b866678888b826fb6fbb222cc8b2c04fe4.
---
 read-cache.c | 47 +----------------------------------------------
 1 file changed, 1 insertion(+), 46 deletions(-)

diff --git a/read-cache.c b/read-cache.c
index df50a8b727c0a6..8db8dc7b4f8ca9 100644
--- a/read-cache.c
+++ b/read-cache.c
@@ -2237,14 +2237,6 @@ int do_read_index(struct index_state *istate, const char *path, int must_exist)
 		load_index_extensions(&p);
 	}
 	munmap((void *)mmap, mmap_size);
-
-	/*
-	 * TODO trace2: replace "the_repository" with the actual repo instance
-	 * that is associated with the given "istate".
-	 */
-	trace2_data_intmax("index", the_repository, "read/version", istate->version);
-	trace2_data_intmax("index", the_repository, "read/cache_nr", istate->cache_nr);
-
 	return istate->cache_nr;
 
 unmap:
@@ -2276,17 +2268,9 @@ int read_index_from(struct index_state *istate, const char *path,
 	if (istate->initialized)
 		return istate->cache_nr;
 
-	/*
-	 * TODO trace2: replace "the_repository" with the actual repo instance
-	 * that is associated with the given "istate".
-	 */
-	trace2_region_enter_printf("index", "do_read_index", the_repository,
-				   "%s", path);
 	trace_performance_enter();
 	ret = do_read_index(istate, path, 0);
 	trace_performance_leave("read cache %s", path);
-	trace2_region_leave_printf("index", "do_read_index", the_repository,
-				   "%s", path);
 
 	split_index = istate->split_index;
 	if (!split_index || is_null_oid(&split_index->base_oid)) {
@@ -2302,11 +2286,7 @@ int read_index_from(struct index_state *istate, const char *path,
 
 	base_oid_hex = oid_to_hex(&split_index->base_oid);
 	base_path = xstrfmt("%s/sharedindex.%s", gitdir, base_oid_hex);
-	trace2_region_enter_printf("index", "shared/do_read_index", the_repository,
-				   "%s", base_path);
 	ret = do_read_index(split_index->base, base_path, 1);
-	trace2_region_leave_printf("index", "shared/do_read_index", the_repository,
-				   "%s", base_path);
 	if (!oideq(&split_index->base_oid, &split_index->base->oid))
 		die("broken index, expect %s in %s, got %s",
 		    base_oid_hex, base_path,
@@ -3017,14 +2997,6 @@ static int do_write_index(struct index_state *istate, struct tempfile *tempfile,
 	istate->timestamp.sec = (unsigned int)st.st_mtime;
 	istate->timestamp.nsec = ST_MTIME_NSEC(st);
 	trace_performance_since(start, "write index, changed mask = %x", istate->cache_changed);
-
-	/*
-	 * TODO trace2: replace "the_repository" with the actual repo instance
-	 * that is associated with the given "istate".
-	 */
-	trace2_data_intmax("index", the_repository, "write/version", istate->version);
-	trace2_data_intmax("index", the_repository, "write/cache_nr", istate->cache_nr);
-
 	return 0;
 }
 
@@ -3044,18 +3016,7 @@ static int commit_locked_index(struct lock_file *lk)
 static int do_write_locked_index(struct index_state *istate, struct lock_file *lock,
 				 unsigned flags)
 {
-	int ret;
-
-	/*
-	 * TODO trace2: replace "the_repository" with the actual repo instance
-	 * that is associated with the given "istate".
-	 */
-	trace2_region_enter_printf("index", "do_write_index", the_repository,
-				   "%s", lock->tempfile->filename.buf);
-	ret = do_write_index(istate, lock->tempfile, 0);
-	trace2_region_leave_printf("index", "do_write_index", the_repository,
-				   "%s", lock->tempfile->filename.buf);
-
+	int ret = do_write_index(istate, lock->tempfile, 0);
 	if (ret)
 		return ret;
 	if (flags & COMMIT_LOCK)
@@ -3149,13 +3110,7 @@ static int write_shared_index(struct index_state *istate,
 	int ret;
 
 	move_cache_to_base_index(istate);
-
-	trace2_region_enter_printf("index", "shared/do_write_index",
-				   the_repository, "%s", (*temp)->filename.buf);
 	ret = do_write_index(si->base, *temp, 1);
-	trace2_region_enter_printf("index", "shared/do_write_index",
-				   the_repository, "%s", (*temp)->filename.buf);
-
 	if (ret)
 		return ret;
 	ret = adjust_shared_perm(get_tempfile_path(*temp));

From 2dc5fabf38ed9c0d88a8e2c7812d490cf0bbc5ef Mon Sep 17 00:00:00 2001
From: Jeff Hostetler <jeffhost@microsoft.com>
Date: Fri, 21 Dec 2018 11:42:36 -0500
Subject: [PATCH 05/25] Revert "trace2: add child classification for transport
 processes"

This reverts commit d83778f2ee71c5e57c4ba7a6a6c4131fefc1300f.
---
 connect.c          | 3 ---
 transport-helper.c | 2 --
 2 files changed, 5 deletions(-)

diff --git a/connect.c b/connect.c
index 75202e81a23157..d72772a36d01ff 100644
--- a/connect.c
+++ b/connect.c
@@ -1255,7 +1255,6 @@ struct child_process *git_connect(int fd[2], const char *url,
 		conn = NULL;
 	} else if (protocol == PROTO_GIT) {
 		conn = git_connect_git(fd, hostandport, path, prog, version, flags);
-		conn->trace2_child_class = "transport/git";
 	} else {
 		struct strbuf cmd = STRBUF_INIT;
 		const char *const *var;
@@ -1298,11 +1297,9 @@ struct child_process *git_connect(int fd[2], const char *url,
 				strbuf_release(&cmd);
 				return NULL;
 			}
-			conn->trace2_child_class = "transport/ssh";
 			fill_ssh_args(conn, ssh_host, port, version, flags);
 		} else {
 			transport_check_allowed("file");
-			conn->trace2_child_class = "transport/file";
 			if (version > 0) {
 				argv_array_pushf(&conn->env_array, GIT_PROTOCOL_ENVIRONMENT "=version=%d",
 						 version);
diff --git a/transport-helper.c b/transport-helper.c
index fa78a8788568ab..35199e50a03e95 100644
--- a/transport-helper.c
+++ b/transport-helper.c
@@ -129,8 +129,6 @@ static struct child_process *get_helper(struct transport *transport)
 		argv_array_pushf(&helper->env_array, "%s=%s",
 				 GIT_DIR_ENVIRONMENT, get_git_dir());
 
-	helper->trace2_child_class = helper->args.argv[0]; /* "remote-<name>" */
-
 	code = start_command(helper);
 	if (code < 0 && errno == ENOENT)
 		die(_("unable to find remote helper for '%s'"), data->name);

From 39fa7147cea0620a066f6c01bb24c3c0fc271975 Mon Sep 17 00:00:00 2001
From: Jeff Hostetler <jeffhost@microsoft.com>
Date: Fri, 21 Dec 2018 11:42:44 -0500
Subject: [PATCH 06/25] Revert "trace2: classify some child processes"

This reverts commit 95597bd7fc7d9d2bae5e9c74b7df601851ffa3ad.
---
 editor.c      | 1 -
 pager.c       | 1 -
 sub-process.c | 1 -
 3 files changed, 3 deletions(-)

diff --git a/editor.c b/editor.c
index 71547674ab4e88..c985eee1f9d1c7 100644
--- a/editor.c
+++ b/editor.c
@@ -78,7 +78,6 @@ static int launch_specified_editor(const char *editor, const char *path,
 		p.argv = args;
 		p.env = env;
 		p.use_shell = 1;
-		p.trace2_child_class = "editor";
 		if (start_command(&p) < 0)
 			return error("unable to start editor '%s'", editor);
 
diff --git a/pager.c b/pager.c
index 1c82a868ee0a7d..bdc75d0b4fad5b 100644
--- a/pager.c
+++ b/pager.c
@@ -103,7 +103,6 @@ void prepare_pager_args(struct child_process *pager_process, const char *pager)
 	argv_array_push(&pager_process->args, pager);
 	pager_process->use_shell = 1;
 	setup_pager_env(&pager_process->env_array);
-	pager_process->trace2_child_class = "pager";
 }
 
 void setup_pager(void)
diff --git a/sub-process.c b/sub-process.c
index 3f4af935557c5e..8d2a1707cfe1a7 100644
--- a/sub-process.c
+++ b/sub-process.c
@@ -88,7 +88,6 @@ int subprocess_start(struct hashmap *hashmap, struct subprocess_entry *entry, co
 	process->out = -1;
 	process->clean_on_exit = 1;
 	process->clean_on_exit_handler = subprocess_exit_handler;
-	process->trace2_child_class = "subprocess";
 
 	err = start_command(process);
 	if (err) {

From fed71620077909a1f06289e75fcd7a9047d57500 Mon Sep 17 00:00:00 2001
From: Jeff Hostetler <jeffhost@microsoft.com>
Date: Fri, 21 Dec 2018 11:42:52 -0500
Subject: [PATCH 07/25] Revert "trace2: add trace2 tracing of major regions in
 wt-status"

This reverts commit 00bac7b6f6783136105196822334f4549b55df5f.
---
 wt-status.c | 17 ++---------------
 1 file changed, 2 insertions(+), 15 deletions(-)

diff --git a/wt-status.c b/wt-status.c
index 682186ed76b47a..955cfa6c638ca7 100644
--- a/wt-status.c
+++ b/wt-status.c
@@ -749,29 +749,16 @@ static int has_unmerged(struct wt_status *s)
 
 void wt_status_collect(struct wt_status *s)
 {
-	trace2_region_enter("status", "worktrees", the_repository);
 	wt_status_collect_changes_worktree(s);
-	trace2_region_leave("status", "worktrees", the_repository);
-
-	if (s->is_initial) {
-		trace2_region_enter("status", "initial", the_repository);
+	if (s->is_initial)
 		wt_status_collect_changes_initial(s);
-		trace2_region_leave("status", "initial", the_repository);
-	} else {
-		trace2_region_enter("status", "index", the_repository);
+	else
 		wt_status_collect_changes_index(s);
-		trace2_region_leave("status", "index", the_repository);
-	}
-
-	trace2_region_enter("status", "untracked", the_repository);
 	wt_status_collect_untracked(s);
-	trace2_region_leave("status", "untracked", the_repository);
 
-	trace2_region_enter("status", "committable", the_repository);
 	wt_status_get_state(&s->state, s->branch && !strcmp(s->branch, "HEAD"));
 	if (s->state.merge_in_progress && !has_unmerged(s))
 		s->committable = 1;
-	trace2_region_leave("status", "committable", the_repository);
 }
 
 void wt_status_collect_free_buffers(struct wt_status *s)

From 095fc201d03a5561006e1940983170e45185253d Mon Sep 17 00:00:00 2001
From: Jeff Hostetler <jeffhost@microsoft.com>
Date: Fri, 21 Dec 2018 11:43:10 -0500
Subject: [PATCH 08/25] Revert "trace2: create new combined trace facility"

This reverts commit 1354d7301ec3bc08f7d1495518500a4f13a713d9.
---
 Makefile                |   9 -
 cache.h                 |   1 -
 common-main.c           |   5 +-
 compat/mingw.c          |   2 -
 compat/mingw.h          |   3 +-
 config.c                |   2 -
 exec-cmd.c              |  10 +-
 git-compat-util.h       |   7 -
 git.c                   |  45 +--
 remote-curl.c           |   7 -
 repository.c            |   2 -
 repository.h            |   3 -
 run-command.c           |  32 +-
 run-command.h           |  10 +-
 sh-i18n--envsubst.c     |   3 -
 t/helper/test-tool.c    |   3 -
 trace2.c                | 743 ----------------------------------------
 trace2.h                | 353 -------------------
 trace2/tr2_cfg.c        |  92 -----
 trace2/tr2_cfg.h        |  23 --
 trace2/tr2_dst.c        |  87 -----
 trace2/tr2_dst.h        |  34 --
 trace2/tr2_sid.c        |  69 ----
 trace2/tr2_sid.h        |  22 --
 trace2/tr2_tbuf.c       |  17 -
 trace2/tr2_tbuf.h       |  19 -
 trace2/tr2_tgt.h        | 119 -------
 trace2/tr2_tgt_event.c  | 531 ----------------------------
 trace2/tr2_tgt_normal.c | 320 -----------------
 trace2/tr2_tgt_perf.c   | 530 ----------------------------
 trace2/tr2_tls.c        | 170 ---------
 trace2/tr2_tls.h        |  99 ------
 usage.c                 |  31 --
 33 files changed, 12 insertions(+), 3391 deletions(-)
 delete mode 100644 trace2.c
 delete mode 100644 trace2.h
 delete mode 100644 trace2/tr2_cfg.c
 delete mode 100644 trace2/tr2_cfg.h
 delete mode 100644 trace2/tr2_dst.c
 delete mode 100644 trace2/tr2_dst.h
 delete mode 100644 trace2/tr2_sid.c
 delete mode 100644 trace2/tr2_sid.h
 delete mode 100644 trace2/tr2_tbuf.c
 delete mode 100644 trace2/tr2_tbuf.h
 delete mode 100644 trace2/tr2_tgt.h
 delete mode 100644 trace2/tr2_tgt_event.c
 delete mode 100644 trace2/tr2_tgt_normal.c
 delete mode 100644 trace2/tr2_tgt_perf.c
 delete mode 100644 trace2/tr2_tls.c
 delete mode 100644 trace2/tr2_tls.h

diff --git a/Makefile b/Makefile
index 9e2a349c9106ef..37c6bc9d76fb97 100644
--- a/Makefile
+++ b/Makefile
@@ -1000,15 +1000,6 @@ LIB_OBJS += tempfile.o
 LIB_OBJS += thread-utils.o
 LIB_OBJS += tmp-objdir.o
 LIB_OBJS += trace.o
-LIB_OBJS += trace2.o
-LIB_OBJS += trace2/tr2_cfg.o
-LIB_OBJS += trace2/tr2_dst.o
-LIB_OBJS += trace2/tr2_sid.o
-LIB_OBJS += trace2/tr2_tbuf.o
-LIB_OBJS += trace2/tr2_tgt_event.o
-LIB_OBJS += trace2/tr2_tgt_normal.o
-LIB_OBJS += trace2/tr2_tgt_perf.o
-LIB_OBJS += trace2/tr2_tls.o
 LIB_OBJS += trailer.o
 LIB_OBJS += transport.o
 LIB_OBJS += transport-helper.o
diff --git a/cache.h b/cache.h
index cf849fe505cd59..dfed668e0dbdd1 100644
--- a/cache.h
+++ b/cache.h
@@ -9,7 +9,6 @@
 #include "gettext.h"
 #include "convert.h"
 #include "trace.h"
-#include "trace2.h"
 #include "string-list.h"
 #include "pack-revindex.h"
 #include "hash.h"
diff --git a/common-main.c b/common-main.c
index bfea45c18d82f3..3728f66b4cce80 100644
--- a/common-main.c
+++ b/common-main.c
@@ -31,9 +31,6 @@ int main(int argc, const char **argv)
 	 * onto stdin/stdout/stderr in the child processes we spawn.
 	 */
 	sanitize_stdfds();
-	restore_sigpipe_to_default();
-
-	trace2_initialize(argv);
 
 	git_resolve_executable_dir(argv[0]);
 
@@ -43,5 +40,7 @@ int main(int argc, const char **argv)
 
 	attr_start();
 
+	restore_sigpipe_to_default();
+
 	return cmd_main(argc, argv);
 }
diff --git a/compat/mingw.c b/compat/mingw.c
index 53ad239cf03faa..29c6c2cae9b444 100644
--- a/compat/mingw.c
+++ b/compat/mingw.c
@@ -1959,7 +1959,6 @@ static int try_shell_exec(const char *cmd, char *const *argv)
 			int status;
 			if (waitpid(pid, &status, 0) < 0)
 				status = 255;
-			trace2_exec_result(status);
 			exit(status);
 		}
 		pid = 1;	/* indicate that we tried but failed */
@@ -1980,7 +1979,6 @@ int mingw_execv(const char *cmd, char *const *argv)
 			return -1;
 		if (waitpid(pid, &status, 0) < 0)
 			status = 255;
-		trace2_exec_result(status);
 		exit(status);
 	}
 	return -1;
diff --git a/compat/mingw.h b/compat/mingw.h
index e391497e8d10c4..ea46b647f18835 100644
--- a/compat/mingw.h
+++ b/compat/mingw.h
@@ -165,7 +165,8 @@ static inline int fcntl(int fd, int cmd, ...)
 	errno = EINVAL;
 	return -1;
 }
-
+/* bash cannot reliably detect negative return codes as failure */
+#define exit(code) exit((code) & 0xff)
 #define sigemptyset(x) (void)0
 static inline int sigaddset(sigset_t *set, int signum)
 { return 0; }
diff --git a/config.c b/config.c
index 95d3613702cf9b..5b39c3ef51131b 100644
--- a/config.c
+++ b/config.c
@@ -2709,8 +2709,6 @@ int git_config_set_gently(const char *key, const char *value)
 void git_config_set(const char *key, const char *value)
 {
 	git_config_set_multivar(key, value, NULL, 0);
-
-	trace2_cmd_set_config(key, value);
 }
 
 /*
diff --git a/exec-cmd.c b/exec-cmd.c
index 640003564e611c..4f81f443105f07 100644
--- a/exec-cmd.c
+++ b/exec-cmd.c
@@ -209,8 +209,6 @@ static int git_get_exec_path(struct strbuf *buf, const char *argv0)
 		return -1;
 	}
 
-	trace2_cmd_path(buf->buf);
-
 	return 0;
 }
 
@@ -330,22 +328,16 @@ const char **prepare_git_cmd(struct argv_array *out, const char **argv)
 int execv_git_cmd(const char **argv)
 {
 	struct argv_array nargv = ARGV_ARRAY_INIT;
-	int err;
 
 	prepare_git_cmd(&nargv, argv);
 	trace_argv_printf(nargv.argv, "trace: exec:");
-	trace2_exec("git", (const char **)nargv.argv);
 
 	/* execvp() can only ever return if it fails */
 	sane_execvp("git", (char **)nargv.argv);
 
-	err = errno;
-	trace_printf("trace: exec failed: %s\n", strerror(err));
-	trace2_exec_result(err);
+	trace_printf("trace: exec failed: %s\n", strerror(errno));
 
 	argv_array_clear(&nargv);
-
-	errno = err;
 	return -1;
 }
 
diff --git a/git-compat-util.h b/git-compat-util.h
index e7aa57730911e7..e6be418b4ee2f2 100644
--- a/git-compat-util.h
+++ b/git-compat-util.h
@@ -1291,13 +1291,6 @@ struct fscache;
 
 extern int cmd_main(int, const char **);
 
-/*
- * Intercept all calls to exit() and route them to trace2 to
- * optionally emit a message before calling the real exit().
- */
-int trace2_cmd_exit_fl(const char *file, int line, int code);
-#define exit(code) exit(trace2_cmd_exit_fl(__FILE__, __LINE__, (code)))
-
 /*
  * You can mark a stack variable with UNLEAK(var) to avoid it being
  * reported as a leak by tools like LSAN or valgrind. The argument
diff --git a/git.c b/git.c
index 1ac52320a424a1..a46643848a070c 100644
--- a/git.c
+++ b/git.c
@@ -149,20 +149,16 @@ static int handle_options(const char ***argv, int *argc, int *envchanged)
 				git_set_exec_path(cmd + 1);
 			else {
 				puts(git_exec_path());
-				trace2_cmd_verb("_query_");
 				exit(0);
 			}
 		} else if (!strcmp(cmd, "--html-path")) {
 			puts(system_path(GIT_HTML_PATH));
-			trace2_cmd_verb("_query_");
 			exit(0);
 		} else if (!strcmp(cmd, "--man-path")) {
 			puts(system_path(GIT_MAN_PATH));
-			trace2_cmd_verb("_query_");
 			exit(0);
 		} else if (!strcmp(cmd, "--info-path")) {
 			puts(system_path(GIT_INFO_PATH));
-			trace2_cmd_verb("_query_");
 			exit(0);
 		} else if (!strcmp(cmd, "-p") || !strcmp(cmd, "--paginate")) {
 			use_pager = 1;
@@ -291,7 +287,6 @@ static int handle_options(const char ***argv, int *argc, int *envchanged)
 			(*argv)++;
 			(*argc)--;
 		} else if (skip_prefix(cmd, "--list-cmds=", &cmd)) {
-			trace2_cmd_verb("_query_");
 			if (!strcmp(cmd, "parseopt")) {
 				struct string_list list = STRING_LIST_INIT_DUP;
 				int i;
@@ -339,14 +334,9 @@ static int handle_alias(int *argcp, const char ***argv)
 			commit_pager_choice();
 
 			child.use_shell = 1;
-			child.trace2_child_class = "shell_alias";
 			argv_array_push(&child.args, alias_string + 1);
 			argv_array_pushv(&child.args, (*argv) + 1);
 
-			trace2_cmd_alias(alias_command, child.args.argv);
-			trace2_cmd_list_config();
-			trace2_cmd_verb("_run_shell_alias_");
-
 			ret = run_command(&child);
 			if (ret >= 0)   /* normal exit */
 				exit(ret);
@@ -381,9 +371,6 @@ static int handle_alias(int *argcp, const char ***argv)
 		/* insert after command name */
 		memcpy(new_argv + count, *argv + 1, sizeof(char *) * *argcp);
 
-		trace2_cmd_alias(alias_command, new_argv);
-		trace2_cmd_list_config();
-
 		*argv = new_argv;
 		*argcp += count - 1;
 
@@ -496,8 +483,6 @@ static int run_builtin(struct cmd_struct *p, int argc, const char **argv)
 		die("pre-command hook aborted command");
 
 	trace_argv_printf(argv, "trace: built-in: git");
-	trace2_cmd_verb(p->cmd);
-	trace2_cmd_list_config();
 
 	validate_cache_entries(&the_index);
 	exit_code = status = p->fn(argc, argv, prefix);
@@ -755,34 +740,23 @@ static void execv_dashed_external(const char **argv)
 	cmd.clean_on_exit = 1;
 	cmd.wait_after_clean = 1;
 	cmd.silent_exec_failure = 1;
-	cmd.trace2_child_class = "dashed";
 
 	if (run_pre_command_hook(cmd.args.argv))
 		die("pre-command hook aborted command");
 
 	trace_argv_printf(cmd.args.argv, "trace: exec:");
-	trace2_exec(NULL, cmd.args.argv);
 
 	/*
 	 * If we fail because the command is not found, it is
 	 * OK to return. Otherwise, we just pass along the status code,
 	 * or our usual generic code if we were not even able to exec
 	 * the program.
-	 *
-	 * If the child process ran and we are now going to exit, emit a
-	 * generic string as our trace2 command verb to indicate that we
-	 * launched a dashed command.
 	 */
 	exit_code = status = run_command(&cmd);
-	trace2_exec_result(status);
-	if (status >= 0) {
-		trace2_cmd_verb("_run_dashed_");
+	if (status >= 0)
 		exit(status);
-	}
-	else if (errno != ENOENT) {
-		trace2_cmd_verb("_run_dashed_");
+	else if (errno != ENOENT)
 		exit(128);
-	}
 
 	run_post_command_hook();
 }
@@ -809,15 +783,6 @@ static int run_argv(int *argcp, const char ***argv)
 			struct argv_array args = ARGV_ARRAY_INIT;
 			int i;
 
-			/*
-			 * The current process is committed to launching a
-			 * child process to run the command named in (**argv)
-			 * and exiting.  Log a generic string as the trace2
-			 * command verb to indicate this.  Note that the child
-			 * process will log the actual verb when it runs.
-			 */
-			trace2_cmd_verb("_run_git_alias_");
-
 			if (get_super_prefix())
 				die("%s doesn't support --super-prefix", **argv);
 
@@ -833,8 +798,8 @@ static int run_argv(int *argcp, const char ***argv)
 			 * if we fail because the command is not found, it is
 			 * OK to return. Otherwise, we just pass along the status code.
 			 */
-			i = run_command_v_opt_tr2(args.argv, RUN_SILENT_EXEC_FAILURE |
-						  RUN_CLEAN_ON_EXIT, "git_alias");
+			i = run_command_v_opt(args.argv, RUN_SILENT_EXEC_FAILURE |
+					      RUN_CLEAN_ON_EXIT);
 			if (i >= 0 || errno != ENOENT)
 				exit(i);
 			die("could not execute builtin %s", **argv);
@@ -965,5 +930,5 @@ int cmd_main(int argc, const char **argv)
 	fprintf(stderr, _("failed to run command '%s': %s\n"),
 		cmd, strerror(errno));
 
-	return trace2_cmd_exit(1);
+	return 1;
 }
diff --git a/remote-curl.c b/remote-curl.c
index 8950b5c383f1b2..1220dffcdc57a1 100644
--- a/remote-curl.c
+++ b/remote-curl.c
@@ -1340,13 +1340,6 @@ int cmd_main(int argc, const char **argv)
 	string_list_init(&options.deepen_not, 1);
 	string_list_init(&options.push_options, 1);
 
-	/*
-	 * Just report "remote-curl" here (folding all the various aliases
-	 * ("git-remote-http", "git-remote-https", and etc.) here since they
-	 * are all just copies of the same actual executable.
-	 */
-	trace2_cmd_verb("remote-curl");
-
 	remote = remote_get(argv[1]);
 
 	if (argc > 2) {
diff --git a/repository.c b/repository.c
index a84055ed1d9e3d..5dd148671811b3 100644
--- a/repository.c
+++ b/repository.c
@@ -113,8 +113,6 @@ static int repo_init_gitdir(struct repository *repo, const char *gitdir)
 void repo_set_worktree(struct repository *repo, const char *path)
 {
 	repo->worktree = real_pathdup(path, 1);
-
-	trace2_def_repo(repo);
 }
 
 static int read_and_verify_repository_format(struct repository_format *format,
diff --git a/repository.h b/repository.h
index 97b03846ba544a..9f16c42c1ed04a 100644
--- a/repository.h
+++ b/repository.h
@@ -90,9 +90,6 @@ struct repository {
 	/* Repository's current hash algorithm, as serialized on disk. */
 	const struct git_hash_algo *hash_algo;
 
-	/* A unique-id for tracing purposes. */
-	int trace2_repo_id;
-
 	/* Configurations */
 
 	/* Indicate if a repository has a different 'commondir' from 'gitdir' */
diff --git a/run-command.c b/run-command.c
index d51250dbf7b339..f8a7f733718378 100644
--- a/run-command.c
+++ b/run-command.c
@@ -713,7 +713,6 @@ int start_command(struct child_process *cmd)
 		cmd->err = fderr[0];
 	}
 
-	trace2_child_start(cmd);
 	trace_run_command(cmd);
 
 	fflush(NULL);
@@ -928,8 +927,6 @@ int start_command(struct child_process *cmd)
 #endif
 
 	if (cmd->pid < 0) {
-		trace2_child_exit(cmd, -1);
-
 		if (need_in)
 			close_pair(fdin);
 		else if (cmd->in)
@@ -968,16 +965,13 @@ int start_command(struct child_process *cmd)
 int finish_command(struct child_process *cmd)
 {
 	int ret = wait_or_whine(cmd->pid, cmd->argv[0], 0);
-	trace2_child_exit(cmd, ret);
 	child_process_clear(cmd);
 	return ret;
 }
 
 int finish_command_in_signal(struct child_process *cmd)
 {
-	int ret = wait_or_whine(cmd->pid, cmd->argv[0], 1);
-	trace2_child_exit(cmd, ret);
-	return ret;
+	return wait_or_whine(cmd->pid, cmd->argv[0], 1);
 }
 
 
@@ -999,18 +993,7 @@ int run_command_v_opt(const char **argv, int opt)
 	return run_command_v_opt_cd_env(argv, opt, NULL, NULL);
 }
 
-int run_command_v_opt_tr2(const char **argv, int opt, const char *tr2_class)
-{
-	return run_command_v_opt_cd_env_tr2(argv, opt, NULL, NULL, tr2_class);
-}
-
 int run_command_v_opt_cd_env(const char **argv, int opt, const char *dir, const char *const *env)
-{
-	return run_command_v_opt_cd_env_tr2(argv, opt, dir, env, NULL);
-}
-
-int run_command_v_opt_cd_env_tr2(const char **argv, int opt, const char *dir, const char *const *env,
-				 const char *tr2_class)
 {
 	struct child_process cmd = CHILD_PROCESS_INIT;
 	cmd.argv = argv;
@@ -1022,7 +1005,6 @@ int run_command_v_opt_cd_env_tr2(const char **argv, int opt, const char *dir, co
 	cmd.clean_on_exit = opt & RUN_CLEAN_ON_EXIT ? 1 : 0;
 	cmd.dir = dir;
 	cmd.env = env;
-	cmd.trace2_child_class = tr2_class;
 	return run_command(&cmd);
 }
 
@@ -1866,15 +1848,6 @@ int run_processes_parallel(int n,
 	int output_timeout = 100;
 	int spawn_cap = 4;
 	struct parallel_processes pp;
-	/*
-	 * TODO Currently all callers of run_processes_parallel()
-	 * are in the submodule code, so hard-coding the category
-	 * is OK for now.  Later, pass in category to this function.
-	 */
-	const char *category = "submodule";
-
-	trace2_region_enter_printf(category, "run_pp", NULL,
-				   "max:%d", ((n < 1) ? online_cpus() : n));
 
 	pp_init(&pp, n, get_next_task, start_failure, task_finished, pp_cb);
 	while (1) {
@@ -1904,8 +1877,5 @@ int run_processes_parallel(int n,
 	}
 
 	pp_cleanup(&pp);
-
-	trace2_region_leave(category, "run_pp", NULL);
-
 	return 0;
 }
diff --git a/run-command.h b/run-command.h
index 36576d790fde68..b17abb44a43722 100644
--- a/run-command.h
+++ b/run-command.h
@@ -10,11 +10,6 @@ struct child_process {
 	struct argv_array args;
 	struct argv_array env_array;
 	pid_t pid;
-
-	int trace2_child_id;
-	uint64_t trace2_child_us_start;
-	const char *trace2_child_class;
-
 	/*
 	 * Using .in, .out, .err:
 	 * - Specify 0 for no redirections (child inherits stdin, stdout,
@@ -80,15 +75,12 @@ extern int run_hook_argv(const char *const *env, const char *name,
 #define RUN_USING_SHELL 16
 #define RUN_CLEAN_ON_EXIT 32
 int run_command_v_opt(const char **argv, int opt);
-int run_command_v_opt_tr2(const char **argv, int opt, const char *tr2_class
-);
+
 /*
  * env (the environment) is to be formatted like environ: "VAR=VALUE".
  * To unset an environment variable use just "VAR".
  */
 int run_command_v_opt_cd_env(const char **argv, int opt, const char *dir, const char *const *env);
-int run_command_v_opt_cd_env_tr2(const char **argv, int opt, const char *dir, const char *const *env,
-				 const char *tr2_class);
 
 /**
  * Execute the given command, sending "in" to its stdin, and capturing its
diff --git a/sh-i18n--envsubst.c b/sh-i18n--envsubst.c
index 2296ba1a2d6361..09c6b445b96312 100644
--- a/sh-i18n--envsubst.c
+++ b/sh-i18n--envsubst.c
@@ -14,7 +14,6 @@
  */
 
 #include "git-compat-util.h"
-#include "trace2.h"
 
 /* Substitution of environment variables in shell format strings.
    Copyright (C) 2003-2007 Free Software Foundation, Inc.
@@ -68,8 +67,6 @@ cmd_main (int argc, const char *argv[])
   /* Default values for command line options.  */
   /* unsigned short int show_variables = 0; */
 
-  trace2_cmd_verb("sh-i18n--envsubst");
-
   switch (argc)
 	{
 	case 1:
diff --git a/t/helper/test-tool.c b/t/helper/test-tool.c
index cfb46a720ea919..52304d0748ce52 100644
--- a/t/helper/test-tool.c
+++ b/t/helper/test-tool.c
@@ -1,6 +1,5 @@
 #include "git-compat-util.h"
 #include "test-tool.h"
-#include "trace2.h"
 
 struct test_cmd {
 	const char *name;
@@ -81,8 +80,6 @@ int cmd_main(int argc, const char **argv)
 		if (!strcmp(cmds[i].name, argv[1])) {
 			argv++;
 			argc--;
-			trace2_cmd_verb(cmds[i].name);
-			trace2_cmd_list_config();
 			return cmds[i].fn(argc, argv);
 		}
 	}
diff --git a/trace2.c b/trace2.c
deleted file mode 100644
index c9844bc742e597..00000000000000
--- a/trace2.c
+++ /dev/null
@@ -1,743 +0,0 @@
-#include "cache.h"
-#include "config.h"
-#include "json-writer.h"
-#include "quote.h"
-#include "run-command.h"
-#include "sigchain.h"
-#include "thread-utils.h"
-#include "version.h"
-#include "trace2/tr2_cfg.h"
-#include "trace2/tr2_dst.h"
-#include "trace2/tr2_sid.h"
-#include "trace2/tr2_tgt.h"
-#include "trace2/tr2_tls.h"
-
-static int trace2_enabled;
-
-static int tr2_next_child_id; /* modify under lock */
-static int tr2_next_repo_id = 1; /* modify under lock. zero is reserved */
-
-/*
- * A table of the builtin TRACE2 targets.  Each of these may be independently
- * enabled or disabled.  Each TRACE2 API will try to write an event to *each*
- * of the enabled targets.
- */
-static struct tr2_tgt *tr2_tgt_builtins[] =
-{
-	&tr2_tgt_normal,
-	&tr2_tgt_perf,
-	&tr2_tgt_event,
-	NULL
-};
-
-#define for_each_builtin(j, tgt_j)			\
-	for (j = 0, tgt_j = tr2_tgt_builtins[j];	\
-	     tgt_j;					\
-	     j++, tgt_j = tr2_tgt_builtins[j])
-
-#define for_each_wanted_builtin(j, tgt_j)	\
-	for_each_builtin(j, tgt_j)		\
-	if (tr2_dst_trace_want(tgt_j->pdst))
-
-/*
- * Force (rather than lazily) initialize any of the requested
- * builtin TRACE2 targets at startup (and before we've seen an
- * actual TRACE2 event call) so we can see if we need to setup
- * the TR2 and TLS machinery.
- *
- * Return the number of builtin targets enabled.
- */
-static int tr2_tgt_want_builtins(void)
-{
-	struct tr2_tgt *tgt_j;
-	int j;
-	int sum = 0;
-
-	for_each_builtin(j, tgt_j) {
-		if (tgt_j->pfn_init())
-			sum++;
-	}
-
-	return sum;
-}
-
-/*
- * Properly terminate each builtin target.  Give each target
- * a chance to write a summary event and/or flush if necessary
- * and then close the fd.
- */
-static void tr2_tgt_disable_builtins(void)
-{
-	struct tr2_tgt *tgt_j;
-	int j;
-
-	for_each_builtin(j, tgt_j) {
-		tgt_j->pfn_term();
-	}
-}
-
-/*****************************************************************
- * TODO remove this section header
- *****************************************************************/
-
-static int tr2main_exit_code;
-
-/*
- * Our atexit routine should run after everything has finished.
- *
- * Note that events generated here might not actually appear if
- * we are writing to fd 1 or 2 and our atexit routine runs after
- * the pager's atexit routine (since it closes them to shutdown
- * the pipes).
- */
-static void tr2main_atexit_handler(void)
-{
-	struct tr2_tgt *tgt_j;
-	int j;
-	uint64_t us_now;
-	uint64_t us_elapsed_absolute;
-
-	us_now = getnanotime() / 1000;
-	us_elapsed_absolute = tr2tls_absolute_elapsed(us_now);
-
-	/*
-	 * Clear any unbalanced regions so that our atexit message
-	 * does not appear nested.  This improves the appearance of
-	 * the trace output if someone calls die(), for example.
-	 */
-	tr2tls_pop_unwind_self();
-	
-	for_each_wanted_builtin(j, tgt_j) {
-		if (tgt_j->pfn_atexit)
-			tgt_j->pfn_atexit(us_elapsed_absolute,
-					  tr2main_exit_code);
-	}
-
-	tr2_tgt_disable_builtins();
-
-	tr2tls_release();
-	tr2_sid_release();
-	tr2_cfg_free_patterns();
-
-	trace2_enabled = 0;
-}
-
-static void tr2main_signal_handler(int signo)
-{
-	struct tr2_tgt *tgt_j;
-	int j;
-	uint64_t us_now;
-	uint64_t us_elapsed_absolute;
-
-	us_now = getnanotime() / 1000;
-	us_elapsed_absolute = tr2tls_absolute_elapsed(us_now);
-
-	for_each_wanted_builtin(j, tgt_j) {
-		if (tgt_j->pfn_signal)
-			tgt_j->pfn_signal(us_elapsed_absolute, signo);
-	}
-
-	sigchain_pop(signo);
-	raise(signo);
-}
-
-/*****************************************************************
- * TODO remove this section header
- *****************************************************************/
-
-void trace2_initialize_fl(const char *file, int line, const char **argv)
-{
-	struct tr2_tgt *tgt_j;
-	int j;
-
-	if (trace2_enabled)
-		return;
-
-	if (!tr2_tgt_want_builtins())
-		return;
-	trace2_enabled = 1;
-
-	tr2_sid_get();
-
-	atexit(tr2main_atexit_handler);
-	sigchain_push(SIGPIPE, tr2main_signal_handler);
-	tr2tls_init();
-
-	/*
-	 * Emit 'version' and 'start' messages on each active builtin target.
-	 */
-	for_each_wanted_builtin(j, tgt_j) {
-		if (tgt_j->pfn_version_fl)
-			tgt_j->pfn_version_fl(file, line);
-		if (tgt_j->pfn_start_fl)
-			tgt_j->pfn_start_fl(file, line, argv);
-	}
-}
-
-int trace2_cmd_exit_fl(const char *file, int line, int code)
-{
-	struct tr2_tgt *tgt_j;
-	int j;
-	uint64_t us_now;
-	uint64_t us_elapsed_absolute;
-
-	code &= 0xff;
-
-	if (!trace2_enabled)
-		return code;
-
-	tr2main_exit_code = code;
-
-	us_now = getnanotime() / 1000;
-	us_elapsed_absolute = tr2tls_absolute_elapsed(us_now);
-
-	for_each_wanted_builtin(j, tgt_j) {
-		if (tgt_j->pfn_exit_fl)
-			tgt_j->pfn_exit_fl(file, line, us_elapsed_absolute, code);
-	}
-
-	return code;
-}
-
-void trace2_cmd_error_va_fl(const char *file, int line,
-			    const char *fmt, va_list ap)
-{
-	struct tr2_tgt *tgt_j;
-	int j;
-
-	if (!trace2_enabled)
-		return;
-
-	/*
-	 * We expect each target function to treat 'ap' as constant
-	 * and use va_copy (because an 'ap' can only be walked once).
-	 */
-	for_each_wanted_builtin(j, tgt_j) {
-		if (tgt_j->pfn_error_va_fl)
-			tgt_j->pfn_error_va_fl(file, line, fmt, ap);
-	}
-}
-
-void trace2_cmd_path_fl(const char *file, int line, const char *pathname)
-{
-	struct tr2_tgt *tgt_j;
-	int j;
-
-	if (!trace2_enabled)
-		return;
-
-	for_each_wanted_builtin(j, tgt_j) {
-		if (tgt_j->pfn_command_path_fl)
-			tgt_j->pfn_command_path_fl(file, line, pathname);
-	}
-}
-
-void trace2_cmd_verb_fl(const char *file, int line, const char *command_verb)
-{
-	struct tr2_tgt *tgt_j;
-	int j;
-
-	if (!trace2_enabled)
-		return;
-
-	for_each_wanted_builtin(j, tgt_j) {
-		if (tgt_j->pfn_command_verb_fl)
-			tgt_j->pfn_command_verb_fl(file, line, command_verb);
-	}
-}
-
-void trace2_cmd_alias_fl(const char *file, int line,
-			 const char *alias, const char **argv)
-{
-	struct tr2_tgt *tgt_j;
-	int j;
-
-	if (!trace2_enabled)
-		return;
-
-	for_each_wanted_builtin(j, tgt_j) {
-		if (tgt_j->pfn_alias_fl)
-			tgt_j->pfn_alias_fl(file, line, alias, argv);
-	}
-}
-
-void trace2_cmd_list_config_fl(const char *file, int line)
-{
-	if (!trace2_enabled)
-		return;
-
-	tr2_cfg_list_config_fl(file, line);
-}
-
-void trace2_cmd_set_config_fl(const char *file, int line,
-			      const char *key, const char *value)
-{
-	if (!trace2_enabled)
-		return;
-
-	tr2_cfg_set_fl(file, line, key, value);
-}
-
-void trace2_child_start_fl(const char *file, int line,
-			   struct child_process *cmd)
-{
-	struct tr2_tgt *tgt_j;
-	int j;
-	uint64_t us_now;
-	uint64_t us_elapsed_absolute;
-
-	if (!trace2_enabled)
-		return;
-
-	us_now = getnanotime() / 1000;
-	us_elapsed_absolute = tr2tls_absolute_elapsed(us_now);
-
-	cmd->trace2_child_id = tr2tls_locked_increment(&tr2_next_child_id);
-	cmd->trace2_child_us_start = us_now;
-
-	for_each_wanted_builtin(j, tgt_j) {
-		if (tgt_j->pfn_child_start_fl)
-			tgt_j->pfn_child_start_fl(file, line,
-						  us_elapsed_absolute, cmd);
-	}
-}
-
-void trace2_child_exit_fl(const char *file, int line,
-			  struct child_process *cmd,
-			  int child_exit_code)
-{
-	struct tr2_tgt *tgt_j;
-	int j;
-	uint64_t us_now;
-	uint64_t us_elapsed_absolute;
-	uint64_t us_elapsed_child;
-
-	if (!trace2_enabled)
-		return;
-
-	us_now = getnanotime() / 1000;
-	us_elapsed_absolute = tr2tls_absolute_elapsed(us_now);
-	
-	if (cmd->trace2_child_us_start)
-		us_elapsed_child = us_now - cmd->trace2_child_us_start;
-	else
-		us_elapsed_child = 0;
-	
-	for_each_wanted_builtin(j, tgt_j) {
-		if (tgt_j->pfn_child_exit_fl)
-			tgt_j->pfn_child_exit_fl(
-				file, line, us_elapsed_absolute,
-				cmd->trace2_child_id,
-				child_exit_code, us_elapsed_child);
-	}
-}
-
-void trace2_exec_fl(const char *file, int line,
-		    const char *exe, const char **argv)
-{
-	struct tr2_tgt *tgt_j;
-	int j;
-	uint64_t us_now;
-	uint64_t us_elapsed_absolute;
-
-	if (!trace2_enabled)
-		return;
-
-	us_now = getnanotime() / 1000;
-	us_elapsed_absolute = tr2tls_absolute_elapsed(us_now);
-
-	for_each_wanted_builtin(j, tgt_j) {
-		if (tgt_j->pfn_exec_fl)
-			tgt_j->pfn_exec_fl(file, line, us_elapsed_absolute,
-					   exe, argv);
-	}
-}
-
-void trace2_exec_result_fl(const char *file, int line, int code)
-{
-	struct tr2_tgt *tgt_j;
-	int j;
-	uint64_t us_now;
-	uint64_t us_elapsed_absolute;
-
-	if (!trace2_enabled)
-		return;
-
-	us_now = getnanotime() / 1000;
-	us_elapsed_absolute = tr2tls_absolute_elapsed(us_now);
-
-	for_each_wanted_builtin(j, tgt_j) {
-		if (tgt_j->pfn_exec_result_fl)
-			tgt_j->pfn_exec_result_fl(file, line,
-						  us_elapsed_absolute,
-						  code);
-	}
-}
-
-void trace2_thread_start_fl(const char *file, int line,
-			    const char *thread_name)
-{
-	struct tr2_tgt *tgt_j;
-	int j;
-	uint64_t us_now;
-	uint64_t us_elapsed_absolute;
-
-	if (!trace2_enabled)
-		return;
-
-	if (tr2tls_is_main_thread())
-	{
-		/*
-		 * We should only be called from the new thread's thread-proc,
-		 * so this is technically a bug.  But in those cases where the
-		 * main thread also runs the thread-proc function (or when we
-		 * are built with threading disabled), we need to allow it.
-		 *
-		 * Convert this call to a region-enter so the nesting looks
-		 * looks correct.  
-		 */
-		trace2_region_enter_printf_fl(file, line, NULL, NULL, NULL,
-					      "thread-proc on main: %s",
-					      thread_name);
-		return;
-	}
-
-	us_now = getnanotime() / 1000;
-	us_elapsed_absolute = tr2tls_absolute_elapsed(us_now);
-
-	tr2tls_create_self(thread_name);
-
-	for_each_wanted_builtin(j, tgt_j) {
-		if (tgt_j->pfn_thread_start_fl)
-			tgt_j->pfn_thread_start_fl(file, line,
-						   us_elapsed_absolute);
-	}
-}
-
-void trace2_thread_exit_fl(const char *file, int line)
-{
-	struct tr2_tgt *tgt_j;
-	int j;
-	uint64_t us_now;
-	uint64_t us_elapsed_absolute;
-	uint64_t us_elapsed_thread;
-
-	if (!trace2_enabled)
-		return;
-
-	if (tr2tls_is_main_thread())
-	{
-		/*
-		 * We should only be called from the exiting thread's thread-proc,
-		 * so this is technically a bug.  But in those cases where the
-		 * main thread also runs the thread-proc function (or when we
-		 * are built with threading disabled), we need to allow it.
-		 *
-		 * Convert this call to a region-leave so the nesting looks
-		 * looks correct.  
-		 */
-		trace2_region_leave_printf_fl(file, line, NULL, NULL, NULL,
-					      "thread-proc on main");
-		return;
-	}
-
-	us_now = getnanotime() / 1000;
-	us_elapsed_absolute = tr2tls_absolute_elapsed(us_now);
-
-	/*
-	 * Clear any unbalanced regions and then get the relative time
-	 * for the outer-most region (which we pushed when the thread
-	 * started).  This gives us the run time of the thread.
-	 */
-	tr2tls_pop_unwind_self();
-	us_elapsed_thread = tr2tls_region_elasped_self(us_now);
-
-	for_each_wanted_builtin(j, tgt_j) {
-		if (tgt_j->pfn_thread_exit_fl)
-			tgt_j->pfn_thread_exit_fl(file, line,
-						  us_elapsed_absolute,
-						  us_elapsed_thread);
-	}
-
-	tr2tls_unset_self();
-}
-
-void trace2_def_param_fl(const char *file, int line,
-			 const char *param, const char *value)
-{
-	struct tr2_tgt *tgt_j;
-	int j;
-
-	if (!trace2_enabled)
-		return;
-
-	for_each_wanted_builtin(j, tgt_j) {
-		if (tgt_j->pfn_param_fl)
-			tgt_j->pfn_param_fl(file, line, param, value);
-	}
-}
-
-void trace2_def_repo_fl(const char *file, int line,
-			struct repository *repo)
-{
-	struct tr2_tgt *tgt_j;
-	int j;
-
-	if (!trace2_enabled)
-		return;
-
-	if (repo->trace2_repo_id)
-		return;
-
-	repo->trace2_repo_id = tr2tls_locked_increment(&tr2_next_repo_id);
-
-	for_each_wanted_builtin(j, tgt_j) {
-		if (tgt_j->pfn_repo_fl)
-			tgt_j->pfn_repo_fl(file, line, repo);
-	}
-}
-
-void trace2_region_enter_printf_va_fl(const char *file, int line,
-				      const char *category,
-				      const char *label,
-				      const struct repository *repo,
-				      const char *fmt, va_list ap)
-{
-	struct tr2_tgt *tgt_j;
-	int j;
-	uint64_t us_now;
-	uint64_t us_elapsed_absolute;
-
-	if (!trace2_enabled)
-		return;
-
-	us_now = getnanotime() / 1000;
-	us_elapsed_absolute = tr2tls_absolute_elapsed(us_now);
-
-	/*
-	 * Print the region-enter message at the current nesting
-	 * (indentation) level and then push a new level.
-	 *
-	 * We expect each target function to treat 'ap' as constant
-	 * and use va_copy.
-	 */
-	for_each_wanted_builtin(j, tgt_j) {
-		if (tgt_j->pfn_region_enter_printf_va_fl)
-			tgt_j->pfn_region_enter_printf_va_fl(
-				file, line, us_elapsed_absolute,
-				category, label, repo, fmt, ap);
-	}
-
-	tr2tls_push_self(us_now);
-}
-
-void trace2_region_enter_fl(const char *file, int line,
-			    const char *category,
-			    const char *label,
-			    const struct repository *repo)
-{
-	trace2_region_enter_printf_va_fl(file, line,
-					 category, label, repo,
-					 NULL, NULL);
-}
-
-void trace2_region_enter_printf_fl(const char *file, int line,
-				   const char *category,
-				   const char *label,
-				   const struct repository *repo,
-				   const char *fmt, ...)
-{
-	va_list ap;
-
-	va_start(ap, fmt);
-	trace2_region_enter_printf_va_fl(file, line,
-					 category, label, repo,
-					 fmt, ap);
-	va_end(ap);
-}
-
-#ifndef HAVE_VARIADIC_MACROS
-void trace2_region_enter_printf(const char *category, const char *label,
-				const struct repository *repo,
-				const char *fmt, ...)
-{
-	va_list ap;
-
-	va_start(ap, fmt);
-	trace2_region_enter_printf_va_fl(NULL, 0,
-					 category, label, repo,
-					 fmt, ap);
-	va_end(ap);
-}
-#endif
-
-void trace2_region_leave_printf_va_fl(const char *file, int line,
-				      const char *category,
-				      const char *label,
-				      const struct repository *repo,
-				      const char *fmt, va_list ap)
-{
-	struct tr2_tgt *tgt_j;
-	int j;
-	uint64_t us_now;
-	uint64_t us_elapsed_absolute;
-	uint64_t us_elapsed_region;
-
-	if (!trace2_enabled)
-		return;
-
-	us_now = getnanotime() / 1000;
-	us_elapsed_absolute = tr2tls_absolute_elapsed(us_now);
-
-	/*
-	 * Get the elapsed time in the current region before we
-	 * pop it off the stack.  Pop the stack.  And then print
-	 * the perf message at the new (shallower) level so that
-	 * it lines up with the corresponding push/enter.
-	 */
-	us_elapsed_region = tr2tls_region_elasped_self(us_now);
-	
-	tr2tls_pop_self();
-
-	/*
-	 * We expect each target function to treat 'ap' as constant
-	 * and use va_copy.
-	 */
-	for_each_wanted_builtin(j, tgt_j) {
-		if (tgt_j->pfn_region_leave_printf_va_fl)
-			tgt_j->pfn_region_leave_printf_va_fl(
-				file, line, us_elapsed_absolute,
-				us_elapsed_region,
-				category, label, repo,
-				fmt, ap);
-	}
-}
-
-void trace2_region_leave_fl(const char *file, int line,
-			    const char *category,
-			    const char *label,
-			    const struct repository *repo)
-{
-	trace2_region_leave_printf_va_fl(file, line,
-					 category, label, repo,
-					 NULL, NULL);
-}
-
-void trace2_region_leave_printf_fl(const char *file, int line,
-				   const char *category,
-				   const char *label,
-				   const struct repository *repo,
-				   const char *fmt, ...)
-{
-	va_list ap;
-
-	va_start(ap, fmt);
-	trace2_region_leave_printf_va_fl(file, line,
-					 category, label, repo,
-					 fmt, ap);
-	va_end(ap);
-}
-
-#ifndef HAVE_VARIADIC_MACROS
-void trace2_region_leave_printf(const char *category, const char *label,
-				const struct repository *repo,
-				const char *fmt, ...)
-{
-	va_list ap;
-
-	va_start(ap, fmt);
-	trace2_region_leave_printf_va_fl(NULL, 0,
-					 category, label, repo,
-					 fmt, ap);
-	va_end(ap);
-}
-#endif
-
-void trace2_data_string_fl(const char *file, int line,
-			   const char *category,
-			   const struct repository *repo,
-			   const char *key,
-			   const char *value)
-{
-	struct tr2_tgt *tgt_j;
-	int j;
-	uint64_t us_now;
-	uint64_t us_elapsed_absolute;
-	uint64_t us_elapsed_region;
-
-	if (!trace2_enabled)
-		return;
-
-	us_now = getnanotime() / 1000;
-	us_elapsed_absolute = tr2tls_absolute_elapsed(us_now);
-	us_elapsed_region = tr2tls_region_elasped_self(us_now);
-
-	for_each_wanted_builtin(j, tgt_j) {
-		if (tgt_j->pfn_data_fl)
-			tgt_j->pfn_data_fl(file, line, us_elapsed_absolute,
-					   us_elapsed_region,
-					   category, repo, key, value);
-	}
-}
-
-void trace2_data_intmax_fl(const char *file, int line,
-			   const char *category,
-			   const struct repository *repo,
-			   const char *key,
-			   intmax_t value)
-{
-	struct strbuf buf_string = STRBUF_INIT;
-
-	if (!trace2_enabled)
-		return;
-
-	strbuf_addf(&buf_string, "%"PRIdMAX, value);
-	trace2_data_string_fl(file, line, category, repo, key, buf_string.buf);
-	strbuf_release(&buf_string);
-}
-
-void trace2_printf_va_fl(const char *file, int line,
-			 const char *fmt, va_list ap)
-{
-	struct tr2_tgt *tgt_j;
-	int j;
-	uint64_t us_now;
-	uint64_t us_elapsed_absolute;
-
-	if (!trace2_enabled)
-		return;
-
-	us_now = getnanotime() / 1000;
-	us_elapsed_absolute = tr2tls_absolute_elapsed(us_now);
-
-	/*
-	 * We expect each target function to treat 'ap' as constant
-	 * and use va_copy.
-	 */
-	for_each_wanted_builtin(j, tgt_j) {
-		if (tgt_j->pfn_printf_va_fl)
-			tgt_j->pfn_printf_va_fl(file, line, us_elapsed_absolute,
-						fmt, ap);
-	}
-}
-
-void trace2_printf_fl(const char *file, int line,
-		      const char *fmt, ...)
-{
-	va_list ap;
-
-	va_start(ap, fmt);
-	trace2_printf_va_fl(file, line, fmt, ap);
-	va_end(ap);
-}
-
-#ifndef HAVE_VARIADIC_MACROS
-void trace2_printf(const char *fmt, ...)
-{
-	va_list ap;
-
-	va_start(ap, fmt);
-	trace2_printf_va_fl(NULL, 0, fmt, ap);
-	va_end(ap);
-}
-#endif
diff --git a/trace2.h b/trace2.h
deleted file mode 100644
index 8cb75a57305307..00000000000000
--- a/trace2.h
+++ /dev/null
@@ -1,353 +0,0 @@
-#ifndef TRACE2_H
-#define TRACE2_H
-
-struct child_process;
-struct repository;
-
-/*
- * The public TRACE2 routines are grouped into the following groups:
- *
- * [] trace2_initialize -- initialization.
- * [] trace2_cmd_*      -- emit command/control messages.
- * [] trace2_child*     -- emit child start/stop messages.
- * [] trace2_exec*      -- emit exec start/stop messages.
- * [] trace2_thread*    -- emit thread start/stop messages.
- * [] trace2_def*       -- emit definition/parameter mesasges.
- * [] trace2_region*    -- emit region nesting messages.
- * [] trace2_data*      -- emit region/thread/repo data messages.
- * [] trace2_printf*    -- legacy trace[1] messages.
- */
-
-
-/*
- * Initialize TRACE2 tracing facility if any of the builtin TRACE2
- * targets are enabled in the environment.  Emits 'version' and
- * 'start' events.
- *
- * Cleanup/Termination is handled automatically by a registered
- * atexit() routine.
- */
-void trace2_initialize_fl(const char *file, int line, const char **argv);
-
-#define trace2_initialize(argv) trace2_initialize_fl(__FILE__, __LINE__, argv)
-
-/*
- * Emit an 'exit' event.
- *
- * Write the exit-code that will be passed to exit() or returned
- * from main().
- *
- * Use this prior to actually calling exit().
- * See "#define exit()" in git-compat-util.h
- */
-int trace2_cmd_exit_fl(const char *file, int line, int code);
-
-#define trace2_cmd_exit(code) (trace2_cmd_exit_fl(__FILE__, __LINE__, (code)))
-
-/*
- * Emit an 'error' event.
- *
- * Write an error message to the TRACE2 targets.
- */
-void trace2_cmd_error_va_fl(const char *file, int line,
-			    const char *fmt, va_list ap);
-
-#define trace2_cmd_error_va(fmt, ap) \
-	trace2_cmd_error_va_fl(__FILE__, __LINE__, (fmt), (ap))
-
-/*
- * Emit a 'pathname' event with the canonical pathname of the current process
- * This gives post-processors a simple field to identify the command without
- * having to parse the argv.  For example, to distinguish invocations from
- * installed versus debug executables.
- */
-void trace2_cmd_path_fl(const char *file, int line, const char *pathname);
-
-#define trace2_cmd_path(p) \
-	trace2_cmd_path_fl(__FILE__, __LINE__, (p))
-
-/*
- * Emit a 'cmd_verb' event with the canonical name of the (usually)
- * builtin command.  This gives post-processors a simple field
- * to identify the command verb without having to parse the argv.
- */
-void trace2_cmd_verb_fl(const char *file, int line, const char *command_verb);
-
-#define trace2_cmd_verb(v) \
-	trace2_cmd_verb_fl(__FILE__, __LINE__, (v))
-
-/*
- * Emit an 'alias' expansion event.
- */
-void trace2_cmd_alias_fl(const char *file, int line,
-			 const char *alias, const char **argv);
-
-#define trace2_cmd_alias(alias, argv) \
-	trace2_cmd_alias_fl(__FILE__, __LINE__, (alias), (argv))
-
-/*
- * Emit one or more 'def_param' events for "interesting" configuration
- * settings.
- *
- * The environment variable "GIT_TR2_CONFIG_PARAMS" can be set to a
- * list of patterns considered important.  For example:
- *
- *    GIT_TR2_CONFIG_PARAMS="core.*,remote.*.url"
- *
- * Note: this routine does a read-only iteration on the config data
- * (using read_early_config()), so it must not be called until enough
- * of the process environment has been established.  This includes the
- * location of the git and worktree directories, expansion of any "-c"
- * and "-C" command line options, and etc.
- */
-void trace2_cmd_list_config_fl(const char *file, int line);
-
-#define trace2_cmd_list_config() \
-	trace2_cmd_list_config_fl(__FILE__, __LINE__)
-
-/*
- * Emit a "def_param" event for the given config key/value pair IF
- * we consider the key to be "interesting".
- *
- * Use this for new/updated config settings created/updated after
- * trace2_cmd_list_config() is called.
- */
-void trace2_cmd_set_config_fl(const char *file, int line,
-			      const char *key, const char *value);
-
-#define trace2_cmd_set_config(k, v) \
-	trace2_cmd_set_config_fl(__FILE__, __LINE__, (k), (v))
-
-/*
- * Emit a 'child_start' event prior to spawning a child process.
- *
- * Before calling optionally set "cmd->trace2_child_class" to a string
- * describing the type of the child process.  For example, "editor" or
- * "pager".
- */
-void trace2_child_start_fl(const char *file, int line,
-			   struct child_process *cmd);
-
-#define trace2_child_start(cmd) \
-	trace2_child_start_fl(__FILE__, __LINE__, (cmd))
-
-/*
- * Emit a 'child_exit' event after the child process completes. 
- */
-void trace2_child_exit_fl(const char *file, int line,
-			  struct child_process *cmd,
-			  int child_exit_code);
-
-#define trace2_child_exit(cmd, code) \
-	trace2_child_exit_fl(__FILE__, __LINE__, (cmd), (code))
-
-/*
- * Emit an 'exec' event prior to calling one of exec(), execv(),
- * execvp(), and etc.  On Unix-derived systems, this will be the
- * last event emitted for the current process, unless the exec
- * fails.  On Windows, exec() behaves like 'child_start' and a
- * waitpid(), so additional events may be emitted.
- */
-void trace2_exec_fl(const char *file, int line,
-		    const char *exe, const char **argv);
-
-#define trace2_exec(exe, argv) \
-	trace2_exec_fl(__FILE__, __LINE__, (exe), (argv))
-
-/*
- * Emit an 'exec_result' when possible.  On Unix-derived systems,
- * this should be called after exec() returns (which only happens
- * when there is an error starting the new process).  On Windows,
- * this should be called after the waitpid().
- */
-void trace2_exec_result_fl(const char *file, int line, int code);
-
-#define trace2_exec_result(code) \
-	trace2_exec_result_fl(__FILE__, __LINE__, (code))
-
-/*
- * Emit a 'thread_start' event.  This must be called from inside the
- * thread-proc to set up the trace2 TLS data for the thread.
- *
- * Thread names should be descriptive, like "preload_index".
- * Thread names will be decorated with an instance number automatically.
- */
-void trace2_thread_start_fl(const char *file, int line,
-				 const char *thread_name);
-
-#define trace2_thread_start(thread_name) \
-	trace2_thread_start_fl(__FILE__, __LINE__, (thread_name))
-
-/*
- * Emit a 'thread_exit' event.  This must be called from inside the
- * thread-proc to report thread-specific data and cleanup TLS data
- * for the thread.
- */
-void trace2_thread_exit_fl(const char *file, int line);
-
-#define trace2_thread_exit() trace2_thread_exit_fl(__FILE__, __LINE__)
-
-/*
- * Emit a 'param' event.
- *
- * Write a "<param> = <value>" pair describing some aspect of the
- * run such as an important configuration setting or command line
- * option that significantly changes command behavior.
- */ 
-void trace2_def_param_fl(const char *file, int line,
-			 const char *param, const char *value);
-
-#define trace2_def_param(param, value) \
-	trace2_def_param_fl(__FILE__, __LINE__, (param), (value))
-
-/*
- * Tell trace2 about a newly instantiated repo object and assign
- * a trace2-repo-id to be used in subsequent activity events.
- *
- * Emits a 'worktree' event for this repo instance.
- */
-void trace2_def_repo_fl(const char *file, int line,
-			struct repository *repo);
-
-#define trace2_def_repo(repo) \
-	trace2_def_repo_fl(__FILE__, __LINE__, repo)
-
-/*
- * Emit a 'region_enter' event for <category>.<label> with optional
- * repo-id and printf message.
- *
- * Enter a new nesting level on the current thread and remember the
- * current time.  This controls the indenting of all subsequent events
- * on this thread.
- */
-void trace2_region_enter_fl(const char *file, int line,
-			    const char *category,
-			    const char *label,
-			    const struct repository *repo);
-
-#define trace2_region_enter(category, label, repo) \
-	trace2_region_enter_fl( \
-		__FILE__, __LINE__, (category), (label), (repo))
-
-void trace2_region_enter_printf_va_fl(const char *file, int line,
-				      const char *category,
-				      const char *label,
-				      const struct repository *repo,
-				      const char *fmt, va_list ap);
-
-#define trace2_region_enter_printf_va(category, label, repo, fmt, ap) \
-	trace2_region_enter_printf_va_fl( \
-		__FILE__, __LINE__, (category), (label), (repo), (fmt), (ap))
-
-void trace2_region_enter_printf_fl(const char *file, int line,
-				   const char *category, const char *label,
-				   const struct repository *repo,
-				   const char *fmt, ...);
-
-#ifdef HAVE_VARIADIC_MACROS
-#define trace2_region_enter_printf(category, label, repo, ...) \
-	trace2_region_enter_printf_fl( \
-		__FILE__, __LINE__, (category), (label), (repo), __VA_ARGS__)
-#else
-__attribute__((format (region_enter_printf, 4, 5)))
-void trace2_region_enter_printf(const char *category, const char *label,
-				const struct repository *repo,
-				const char *fmt, ...);
-#endif
-
-/*
- * Emit a 'region_leave' event for <category>.<label> with optional
- * repo-id and printf message.
- *
- * Leave current nesting level and report the elapsed time spent
- * in this nesting level.
- */
-void trace2_region_leave_fl(const char *file, int line,
-			    const char *category,
-			    const char *label,
-			    const struct repository *repo);
-
-#define trace2_region_leave(category, label, repo) \
-	trace2_region_leave_fl( \
-		__FILE__, __LINE__, (category), (label), (repo))
-
-void trace2_region_leave_printf_va_fl(const char *file, int line,
-				      const char *category,
-				      const char *label,
-				      const struct repository *repo,
-				      const char *fmt, va_list ap);
-
-#define trace2_region_leave_printf_va(category, label, repo, fmt, ap) \
-	trace2_region_leave_printf_va_fl( \
-		__FILE__, __LINE__, (category), (label), (repo), (fmt), (ap))
-
-void trace2_region_leave_printf_fl(const char *file, int line,
-				   const char *category, const char *label,
-				   const struct repository *repo,
-				   const char *fmt, ...);
-
-#ifdef HAVE_VARIADIC_MACROS
-#define trace2_region_leave_printf(category, label, repo, ...) \
-	trace2_region_leave_printf_fl( \
-		__FILE__, __LINE__, (category), (label), (repo), __VA_ARGS__)
-#else
-__attribute__((format (region_leave_printf, 4, 5)))
-void trace2_region_leave_printf(const char *category, const char *label,
-				const struct repository *repo,
-				const char *fmt, ...);
-#endif
-
-/*
- * Emit a key-value pair 'data' event of the form <category>.<key> = <value>.
- * This event implicitly contains information about thread, nesting region,
- * and optional repo-id.
- *
- * On event-based TRACE2 targets, this generates a 'data' event suitable
- * for post-processing.  On printf-based TRACE2 targets, this is converted
- * into a fixed-format printf message.
- */
-void trace2_data_string_fl(const char *file, int line,
-			   const char *category,
-			   const struct repository *repo,
-			   const char *key,
-			   const char *value);
-
-#define trace2_data_string(category, repo, key, value) \
-	trace2_data_string_fl( \
-		__FILE__, __LINE__, (category), (repo), (key), (value))
-
-void trace2_data_intmax_fl(const char *file, int line,
-			   const char *category,
-			   const struct repository *repo,
-			   const char *key,
-			   intmax_t value);
-
-#define trace2_data_intmax(category, repo, key, value) \
-	trace2_data_intmax_fl( \
-		__FILE__, __LINE__, (category), (repo), (key), (value))
-
-/*
- * Emit a 'printf' event.
- *
- * Write an arbitrary formatted message to the TRACE2 targets.  These
- * text messages should be considered as human-readable strings without
- * any formatting guidelines.  Post-processors may choose to ignore
- * them.
- */
-void trace2_printf_va_fl(const char *file, int line,
-			 const char *fmt, va_list ap);
-
-#define trace2_printf_va(fmt, ap) \
-	trace2_printf_va_fl(__FILE__, __LINE__, (fmt), (ap))
-
-void trace2_printf_fl(const char *file, int line, const char *fmt, ...);
-
-#ifdef HAVE_VARIADIC_MACROS
-#define trace2_printf(...) \
-	trace2_printf_fl(__FILE__, __LINE__, __VA_ARGS__)
-#else
-__attribute__((format (printf, 1, 2)))
-void trace2_printf(const char *fmt, ...);
-#endif
-
-#endif /* TRACE2_H */
diff --git a/trace2/tr2_cfg.c b/trace2/tr2_cfg.c
deleted file mode 100644
index 0f16ed09f701f1..00000000000000
--- a/trace2/tr2_cfg.c
+++ /dev/null
@@ -1,92 +0,0 @@
-#include "cache.h"
-#include "config.h"
-#include "tr2_cfg.h"
-
-#define TR2_CFG_PARAM "GIT_TR2_CONFIG_PARAMS"
-
-static struct strbuf **tr2_cfg_patterns;
-static int tr2_cfg_count_patterns;
-static int tr2_cfg_loaded;
-
-/*
- * Parse a string containing a comma-delimited list of config keys
- * or wildcard patterns into a list of strbufs.
- */
-static int tr2_cfg_load_patterns(void)
-{
-	struct strbuf **s;
-	const char *envvar;
-
-	if (tr2_cfg_loaded)
-		return tr2_cfg_count_patterns;
-	tr2_cfg_loaded = 1;
-
-	envvar = getenv(TR2_CFG_PARAM);
-	if (!envvar || !*envvar)
-		return tr2_cfg_count_patterns;
-
-	tr2_cfg_patterns = strbuf_split_buf(envvar, strlen(envvar), ',', -1);
-	for (s = tr2_cfg_patterns; *s; s++) {
-		struct strbuf *buf = *s;
-
-		if (buf->len && buf->buf[buf->len - 1] == ',')
-			strbuf_setlen(buf, buf->len - 1);
-		strbuf_trim_trailing_newline(*s);
-		strbuf_trim(*s);
-	}
-
-	tr2_cfg_count_patterns = s - tr2_cfg_patterns;
-	return tr2_cfg_count_patterns;
-}
-
-void tr2_cfg_free_patterns(void)
-{
-	if (tr2_cfg_patterns)
-		strbuf_list_free(tr2_cfg_patterns);
-	tr2_cfg_count_patterns = 0;
-	tr2_cfg_loaded = 0;
-}
-
-struct tr2_cfg_data
-{
-	const char *file;
-	int line;
-};
-
-/*
- * See if the given config key matches any of our patterns of interest.
- */
-static int tr2_cfg_cb(const char *key, const char *value, void *d)
-{
-	struct strbuf **s;
-	struct tr2_cfg_data *data = (struct tr2_cfg_data *)d;
-
-	for (s = tr2_cfg_patterns; *s; s++) {
-		struct strbuf *buf = *s;
-		int wm = wildmatch(buf->buf, key, WM_CASEFOLD);
-		if (wm == WM_MATCH) {
-			trace2_def_param_fl(data->file, data->line, key, value);
-			return 0;
-		}
-	}
-
-	return 0;
-}
-
-void tr2_cfg_list_config_fl(const char *file, int line)
-{
-	struct tr2_cfg_data data = { file, line };
-
-	if (tr2_cfg_load_patterns() > 0)
-		read_early_config(tr2_cfg_cb, &data);
-}
-
-void tr2_cfg_set_fl(const char *file, int line,
-		    const char *key, const char *value)
-{
-	struct tr2_cfg_data data = { file, line };
-
-	if (tr2_cfg_load_patterns() > 0)
-		tr2_cfg_cb(key, value, &data);
-}
-
diff --git a/trace2/tr2_cfg.h b/trace2/tr2_cfg.h
deleted file mode 100644
index 1e3db7e496a782..00000000000000
--- a/trace2/tr2_cfg.h
+++ /dev/null
@@ -1,23 +0,0 @@
-#ifndef TR2_CFG_H
-#define TR2_CFG_H
-
-/*
- * This file contains "private/protected" declarations for TRACE2.
- */
-
-/*
- * Iterate over all config settings and emit 'def_param' events for the
- * "interesting" ones to TRACE2.
- */
-void tr2_cfg_list_config_fl(const char *file, int line);
-
-/*
- * Emit a "def_param" event for the given key/value pair IF we consider
- * the key to be "interesting".
- */
-void tr2_cfg_set_fl(const char *file, int line,
-		    const char *key, const char *value);
-
-void tr2_cfg_free_patterns(void);
-
-#endif /* TR2_CFG_H */
diff --git a/trace2/tr2_dst.c b/trace2/tr2_dst.c
deleted file mode 100644
index e68c62629d2f5a..00000000000000
--- a/trace2/tr2_dst.c
+++ /dev/null
@@ -1,87 +0,0 @@
-#include "cache.h"
-#include "trace2/tr2_dst.h"
-
-/*
- * This file contains "private/protected" declarations for TRACE2.
- */
-
-void tr2_dst_trace_disable(struct tr2_dst *dst)
-{
-	if (dst->need_close)
-		close(dst->fd);
-	dst->fd = 0;
-	dst->initialized = 1;
-	dst->need_close = 0;
-}
-
-int tr2_dst_get_trace_fd(struct tr2_dst *dst)
-{
-	const char *trace;
-
-	/* don't open twice */
-	if (dst->initialized)
-		return dst->fd;
-
-	trace = getenv(dst->env_var_name);
-
-	if (!trace || !strcmp(trace, "") ||
-	    !strcmp(trace, "0") || !strcasecmp(trace, "false"))
-		dst->fd = 0;
-	else if (!strcmp(trace, "1") || !strcasecmp(trace, "true"))
-		dst->fd = STDERR_FILENO;
-	else if (strlen(trace) == 1 && isdigit(*trace))
-		dst->fd = atoi(trace);
-	else if (is_absolute_path(trace)) {
-		int fd = open(trace, O_WRONLY | O_APPEND | O_CREAT, 0666);
-		if (fd == -1) {
-			warning("could not open '%s' for tracing: %s",
-				trace, strerror(errno));
-			tr2_dst_trace_disable(dst);
-		} else {
-			dst->fd = fd;
-			dst->need_close = 1;
-		}
-	} else {
-		warning("unknown trace value for '%s': %s\n"
-			"         If you want to trace into a file, then please set %s\n"
-			"         to an absolute pathname (starting with /)",
-			dst->env_var_name, trace, dst->env_var_name);
-		tr2_dst_trace_disable(dst);
-	}
-
-	dst->initialized = 1;
-	return dst->fd;
-}
-
-int tr2_dst_trace_want(struct tr2_dst *dst)
-{
-	return !!tr2_dst_get_trace_fd(dst);
-}
-
-void tr2_dst_write_line(struct tr2_dst *dst, struct strbuf *buf_line)
-{
-	strbuf_complete_line(buf_line); /* ensure final NL on buffer */
-
-	/*
-	 * We do not use write_in_full() because we do not want
-	 * a short-write to try again.  We are using O_APPEND mode
-	 * files and the kernel handles the atomic seek+write. If
-	 * another thread or git process is concurrently writing to
-	 * this fd or file, our remainder-write may not be contiguous
-	 * with our initial write of this message.  And that will
-	 * confuse readers.  So just don't bother.
-	 *
-	 * It is assumed that TRACE2 messages are short enough that
-	 * the system can write them in 1 attempt and we won't see
-	 * a short-write.
-	 *
-	 * If we get an IO error, just close the trace dst.
-	 */
-
-	if (write(tr2_dst_get_trace_fd(dst),
-		  buf_line->buf, buf_line->len) < 0) {
-		warning("unable to write trace for '%s': %s",
-			dst->env_var_name, strerror(errno));
-		tr2_dst_trace_disable(dst);
-	}
-}
diff --git a/trace2/tr2_dst.h b/trace2/tr2_dst.h
deleted file mode 100644
index 90902a664cf62c..00000000000000
--- a/trace2/tr2_dst.h
+++ /dev/null
@@ -1,34 +0,0 @@
-#ifndef TR2_DST_H
-#define TR2_DST_H
-
-struct tr2_dst {
-	const char * const env_var_name;
-	int fd;
-	unsigned int initialized : 1;
-	unsigned int  need_close : 1;
-};
-
-/*
- * Disable TRACE2 on the destination.  In TRACE2 a destination (DST)
- * wraps a file descriptor; it is associated with a TARGET which
- * defines the formatting.
- */
-void tr2_dst_trace_disable(struct tr2_dst *dst);
-
-/*
- * Return the file descriptor for the DST.
- * If 0, the dst is closed or disabled.
- */
-int tr2_dst_get_trace_fd(struct tr2_dst *dst);
-
-/*
- * Return true if the DST is opened for writing.
- */
-int tr2_dst_trace_want(struct tr2_dst *dst);
-
-/*
- * Write a single line/message to the trace file.
- */
-void tr2_dst_write_line(struct tr2_dst *dst, struct strbuf *buf_line);
-
-#endif /* TR2_DST_H */
diff --git a/trace2/tr2_sid.c b/trace2/tr2_sid.c
deleted file mode 100644
index 7fba400e9766f6..00000000000000
--- a/trace2/tr2_sid.c
+++ /dev/null
@@ -1,69 +0,0 @@
-#include "cache.h"
-#include "trace2/tr2_sid.h"
-
-/*
- * This file contains "private/protected" routines for TRACE2.
- */
-
-static struct strbuf tr2sid_buf = STRBUF_INIT;
-static int tr2sid_nr_git_parents;
-
-/*
- * Compute a "unique" session id (SID) for the current process.  This allows
- * all events from this process to have a single label (much like a PID).
- *
- * Export this into our environment so that all child processes inherit it.
- *
- * If we were started by another git instance, use our parent's SID as a
- * prefix.  (This lets us track parent/child relationships even if there
- * is an intermediate shell process.)
- *
- * Additionally, count the number of nested git processes.
- */
-static void tr2_sid_compute(void)
-{
-	uint64_t us_now;
-	const char *parent_sid;
-
-	if (tr2sid_buf.len)
-		return;
-
-	parent_sid = getenv("SLOG_PARENT_SID");
-	if (parent_sid && *parent_sid) {
-		const char *p;
-		for (p = parent_sid; *p; p++)
-			if (*p == '/')
-				tr2sid_nr_git_parents++;
-
-		strbuf_addstr(&tr2sid_buf, parent_sid);
-		strbuf_addch(&tr2sid_buf, '/');
-		tr2sid_nr_git_parents++;
-	}
-
-	us_now = getnanotime() / 1000;
-	strbuf_addf(&tr2sid_buf, "%"PRIuMAX"-%"PRIdMAX,
-		    (uintmax_t)us_now, (intmax_t)getpid());
-
-	setenv("SLOG_PARENT_SID", tr2sid_buf.buf, 1);
-}
-
-const char *tr2_sid_get(void)
-{
-	if (!tr2sid_buf.len)
-		tr2_sid_compute();
-
-	return tr2sid_buf.buf;
-}
-
-int tr2_sid_depth(void)
-{
-	if (!tr2sid_buf.len)
-		tr2_sid_compute();
-
-	return tr2sid_nr_git_parents;
-}
-
-void tr2_sid_release(void)
-{
-	strbuf_release(&tr2sid_buf);
-}
diff --git a/trace2/tr2_sid.h b/trace2/tr2_sid.h
deleted file mode 100644
index 30fc14b894be02..00000000000000
--- a/trace2/tr2_sid.h
+++ /dev/null
@@ -1,22 +0,0 @@
-#ifndef TR2_SID_H
-#define TR2_SID_H
-
-/*
- * This file contains "private/protected" declarations for TRACE2.
- */
-
-/*
- * Get our session id. Compute if necessary.
- */
-const char *tr2_sid_get(void);
-
-/*
- * Get our process depth.  A top-level git process invoked from the
- * command line will have depth=0.  A child git process will have
- * depth=1 and so on.
- */
-int tr2_sid_depth(void);
-
-void tr2_sid_release(void);
-
-#endif /* TR2_SID_H */
diff --git a/trace2/tr2_tbuf.c b/trace2/tr2_tbuf.c
deleted file mode 100644
index 98c4c25770adb8..00000000000000
--- a/trace2/tr2_tbuf.c
+++ /dev/null
@@ -1,17 +0,0 @@
-#include "cache.h"
-#include "tr2_tbuf.h"
-
-void tr2_tbuf_current_time(struct tr2_tbuf *tb)
-{
-	struct timeval tv;
-	struct tm tm;
-	time_t secs;
-
-	gettimeofday(&tv, NULL);
-	secs = tv.tv_sec;
-	localtime_r(&secs, &tm);
-
-	xsnprintf(tb->buf, sizeof(tb->buf), "%02d:%02d:%02d.%06ld",
-		  tm.tm_hour, tm.tm_min, tm.tm_sec, (long)tv.tv_usec);
-}
-
diff --git a/trace2/tr2_tbuf.h b/trace2/tr2_tbuf.h
deleted file mode 100644
index 63a035b6e9fa94..00000000000000
--- a/trace2/tr2_tbuf.h
+++ /dev/null
@@ -1,19 +0,0 @@
-#ifndef TR2_TBUF_H
-#define TR2_TBUF_H
-
-/*
- * This file contains "private/protected" declarations for TRACE2.
- */
-
-/*
- * A simple wrapper around a fixed buffer to avoid C syntax
- * quirks and the need to pass around an additional size_t
- * argument.
- */
-struct tr2_tbuf {
-	char buf[24];
-};
-
-void tr2_tbuf_current_time(struct tr2_tbuf *tb);
-
-#endif /* TR2_TBUF_H */
diff --git a/trace2/tr2_tgt.h b/trace2/tr2_tgt.h
deleted file mode 100644
index 9d93add2236a69..00000000000000
--- a/trace2/tr2_tgt.h
+++ /dev/null
@@ -1,119 +0,0 @@
-#ifndef TR2_TGT_H
-#define TR2_TGT_H
-
-/*
- * This file contains "private/protected" declarations for TRACE2.
- */
-
-/*
- * Function prototypes for a TRACE2 "target" vtable.
- */
-
-typedef int (tr2_tgt_init_t)(void);
-typedef void (tr2_tgt_term_t)(void);
-
-typedef void (tr2_tgt_evt_version_fl_t)
-	(const char *file, int line);
-
-typedef void (tr2_tgt_evt_start_fl_t)
-	(const char *file, int line, const char **argv);
-typedef void (tr2_tgt_evt_exit_fl_t)
-	(const char *file, int line, uint64_t us_elapsed_absolute, int code);
-typedef void (tr2_tgt_evt_signal_t)
-	(uint64_t us_elapsed_absolute, int signo);
-typedef void (tr2_tgt_evt_atexit_t)
-	(uint64_t us_elapsed_absolute, int code);
-
-typedef void (tr2_tgt_evt_error_va_fl_t)
-	(const char *file, int line, const char *fmt, va_list ap);
-
-typedef void (tr2_tgt_evt_command_path_fl_t)
-	(const char *file, int line, const char *command_path);
-typedef void (tr2_tgt_evt_command_verb_fl_t)
-	(const char *file, int line, const char *command_verb);
-
-typedef void (tr2_tgt_evt_alias_fl_t)
-	(const char *file, int line, const char *alias, const char **argv);
-
-typedef void (tr2_tgt_evt_child_start_fl_t)
-	(const char *file, int line, uint64_t us_elapsed_absolute,
-	 const struct child_process *cmd);
-typedef void (tr2_tgt_evt_child_exit_fl_t)
-	(const char *file, int line, uint64_t us_elapsed_absolute, int cid,
-	 int code, uint64_t us_elapsed_child);
-
-typedef void (tr2_tgt_evt_thread_start_fl_t)
-	(const char *file, int line, uint64_t us_elapsed_absolute);
-typedef void (tr2_tgt_evt_thread_exit_fl_t)
-	(const char *file, int line, uint64_t us_elapsed_absolute,
-	 uint64_t us_elapsed_thread);
-
-typedef void (tr2_tgt_evt_exec_fl_t)
-	(const char *file, int line, uint64_t us_elapsed_absolute,
-	 const char *exe, const char **argv);
-typedef void (tr2_tgt_evt_exec_result_fl_t)
-	(const char *file, int line, uint64_t us_elapsed_absolute, int code);
-
-typedef void (tr2_tgt_evt_param_fl_t)
-	(const char *file, int line, const char *param, const char *value);
-
-typedef void (tr2_tgt_evt_repo_fl_t)
-	(const char *file, int line, const struct repository *repo);
-
-typedef void (tr2_tgt_evt_region_enter_printf_va_fl_t)
-	(const char *file, int line, uint64_t us_elapsed_absolute,
-	 const char *category, const char *label, const struct repository *repo,
-	 const char *fmt, va_list ap);
-typedef void (tr2_tgt_evt_region_leave_printf_va_fl_t)
-	(const char *file, int line, uint64_t us_elapsed_absolute,
-	 uint64_t us_elapsed_region, const char *category, const char *label,
-	 const struct repository *repo, const char *fmt, va_list ap);
-
-typedef void (tr2_tgt_evt_data_fl_t)
-	(const char *file, int line, uint64_t us_elapsed_absolute,
-	 uint64_t us_elapsed_region, const char *category,
-	 const struct repository *repo, const char *key, const char *value);
-
-typedef void (tr2_tgt_evt_printf_va_fl_t)
-	(const char *file, int line, uint64_t us_elapsed_absolute,
-	 const char *fmt, va_list ap);
-
-/*
- * "vtable" for a TRACE2 target.  Use NULL if a target does not want
- * to emit that message.
- */
-struct tr2_tgt
-{
-	struct tr2_dst                          *pdst;
-
-	tr2_tgt_init_t                          *pfn_init;
-	tr2_tgt_term_t                          *pfn_term;
-
-	tr2_tgt_evt_version_fl_t                *pfn_version_fl;
-	tr2_tgt_evt_start_fl_t                  *pfn_start_fl;
-	tr2_tgt_evt_exit_fl_t                   *pfn_exit_fl;
-	tr2_tgt_evt_signal_t                    *pfn_signal;
-	tr2_tgt_evt_atexit_t                    *pfn_atexit;
-	tr2_tgt_evt_error_va_fl_t               *pfn_error_va_fl;
-	tr2_tgt_evt_command_path_fl_t           *pfn_command_path_fl;
-	tr2_tgt_evt_command_verb_fl_t           *pfn_command_verb_fl;
-	tr2_tgt_evt_alias_fl_t                  *pfn_alias_fl;
-	tr2_tgt_evt_child_start_fl_t            *pfn_child_start_fl;
-	tr2_tgt_evt_child_exit_fl_t             *pfn_child_exit_fl;
-	tr2_tgt_evt_thread_start_fl_t           *pfn_thread_start_fl;
-	tr2_tgt_evt_thread_exit_fl_t            *pfn_thread_exit_fl;
-	tr2_tgt_evt_exec_fl_t                   *pfn_exec_fl;
-	tr2_tgt_evt_exec_result_fl_t            *pfn_exec_result_fl;
-	tr2_tgt_evt_param_fl_t                  *pfn_param_fl;
-	tr2_tgt_evt_repo_fl_t                   *pfn_repo_fl;
-	tr2_tgt_evt_region_enter_printf_va_fl_t *pfn_region_enter_printf_va_fl;
-	tr2_tgt_evt_region_leave_printf_va_fl_t *pfn_region_leave_printf_va_fl;
-	tr2_tgt_evt_data_fl_t                   *pfn_data_fl;
-	tr2_tgt_evt_printf_va_fl_t              *pfn_printf_va_fl;
-};
-
-extern struct tr2_tgt tr2_tgt_event;
-extern struct tr2_tgt tr2_tgt_normal;
-extern struct tr2_tgt tr2_tgt_perf;
-
-#endif /* TR2_TGT_H */
diff --git a/trace2/tr2_tgt_event.c b/trace2/tr2_tgt_event.c
deleted file mode 100644
index 9e653d111b9846..00000000000000
--- a/trace2/tr2_tgt_event.c
+++ /dev/null
@@ -1,531 +0,0 @@
-#include "cache.h"
-#include "config.h"
-#include "json-writer.h"
-#include "run-command.h"
-#include "version.h"
-#include "trace2/tr2_dst.h"
-#include "trace2/tr2_tbuf.h"
-#include "trace2/tr2_sid.h"
-#include "trace2/tr2_tgt.h"
-#include "trace2/tr2_tls.h"
-
-/*
- * This file contains "private/protected" declarations for TRACE2.
- */
-
-static struct tr2_dst tr2dst_event  = { "GIT_TR2_EVENT", 0, 0, 0 };
-
-/*
- * The version number of the JSON data generated by the EVENT target
- * in this source file.  Update this if you make a significant change
- * to the JSON fields or message structure.  You probably do not need
- * to update this if you just add another call to one of the existing
- * TRACE2 API methods.
- */
-#define GIT_TR2_EVENT_VERSION "1"
-
-/*
- * Region nesting limit for messages written to the event target.
- *
- * The "region_enter" and "region_leave" messages (especially recursive
- * messages such as those produced while diving the worktree or index)
- * are primarily intended for the performance target during debugging.
- *
- * Some of the outer-most messages, however, may be of interest to the
- * event target.  Set this environment variable to a larger integer for
- * more detail in the event target.
- */
-#define GIT_TR2_EVENT_NESTING "GIT_TR2_EVENT_NESTING"
-static int tr2env_event_nesting_wanted = 2;
-
-static int fn_init(void)
-{
-	int want = tr2_dst_trace_want(&tr2dst_event);
-	int want_nesting;
-	char *nesting;
-
-	if (!want)
-		return want;
-
-	nesting = getenv(GIT_TR2_EVENT_NESTING);
-	if (nesting && ((want_nesting = atoi(nesting)) > 0))
-		tr2env_event_nesting_wanted = want_nesting;
-
-	return want;
-}
-
-static void fn_term(void)
-{
-	tr2_dst_trace_disable(&tr2dst_event);
-}
-
-/*
- * Append common key-value pairs to the currently open JSON object.
- *     "event:"<event_name>"
- *      "sid":"<sid>"
- *   "thread":"<thread_name>"
- *     "time":"<time>"
- *     "file":"<filename>"
- *     "line":<line_number>
- *     "repo":<repo_id>
- */
-static void event_fmt_prepare(const char *event_name,
-			      const char *file, int line,
-			      const struct repository *repo,
-			      struct json_writer *jw)
-{
-	struct tr2tls_thread_ctx *ctx = tr2tls_get_self();
-	struct tr2_tbuf tb_now;
-
-	jw_object_string(jw, "event", event_name);
-	jw_object_string(jw, "sid", tr2_sid_get());
-	jw_object_string(jw, "thread", ctx->thread_name.buf);
-
-	tr2_tbuf_current_time(&tb_now);
-	jw_object_string(jw, "time", tb_now.buf);
-
-	if (file && *file) {
-		jw_object_string(jw, "file", file);
-		jw_object_intmax(jw, "line", line);
-	}
-
-	if (repo)
-		jw_object_intmax(jw, "repo", repo->trace2_repo_id);
-}
-
-static void fn_version_fl(const char *file, int line)
-{
-	const char *event_name = "version";
-	struct json_writer jw = JSON_WRITER_INIT;
-
-	jw_object_begin(&jw, 0);
-	event_fmt_prepare(event_name, file, line, NULL, &jw);
-	jw_object_string(&jw, "evt", GIT_TR2_EVENT_VERSION);
-	jw_object_string(&jw, "exe", git_version_string);
-	jw_end(&jw);
-
-	tr2_dst_write_line(&tr2dst_event, &jw.json);
-	jw_release(&jw);
-}
-
-static void fn_start_fl(const char *file, int line, const char **argv)
-{
-	const char *event_name = "start";
-	struct json_writer jw = JSON_WRITER_INIT;
-
-	jw_object_begin(&jw, 0);
-	event_fmt_prepare(event_name, file, line, NULL, &jw);
-	jw_object_inline_begin_array(&jw, "argv");
-	jw_array_argv(&jw, argv);
-	jw_end(&jw);
-	jw_end(&jw);
-
-	tr2_dst_write_line(&tr2dst_event, &jw.json);
-	jw_release(&jw);
-}
-
-static void fn_exit_fl(const char *file, int line,
-		       uint64_t us_elapsed_absolute, int code)
-{
-	const char *event_name = "exit";
-	struct json_writer jw = JSON_WRITER_INIT;
-	double t_abs = (double)us_elapsed_absolute / 1000000.0;
-
-	jw_object_begin(&jw, 0);
-	event_fmt_prepare(event_name, file, line, NULL, &jw);
-	jw_object_double(&jw, "t_abs", 6, t_abs);
-	jw_object_intmax(&jw, "code", code);
-	jw_end(&jw);
-
-	tr2_dst_write_line(&tr2dst_event, &jw.json);
-	jw_release(&jw);
-}
-
-static void fn_signal(uint64_t us_elapsed_absolute, int signo)
-{
-	const char *event_name = "signal";
-	struct json_writer jw = JSON_WRITER_INIT;
-	double t_abs = (double)us_elapsed_absolute / 1000000.0;
-
-	jw_object_begin(&jw, 0);
-	event_fmt_prepare(event_name, __FILE__, __LINE__, NULL, &jw);
-	jw_object_double(&jw, "t_abs", 6, t_abs);
-	jw_object_intmax(&jw, "signo", signo);
-	jw_end(&jw);
-
-	tr2_dst_write_line(&tr2dst_event, &jw.json);
-	jw_release(&jw);
-}
-
-static void fn_atexit(uint64_t us_elapsed_absolute, int code)
-{
-	const char *event_name = "atexit";
-	struct json_writer jw = JSON_WRITER_INIT;
-	double t_abs = (double)us_elapsed_absolute / 1000000.0;
-
-	jw_object_begin(&jw, 0);
-	event_fmt_prepare(event_name, __FILE__, __LINE__, NULL, &jw);
-	jw_object_double(&jw, "t_abs", 6, t_abs);
-	jw_object_intmax(&jw, "code", code);
-	jw_end(&jw);
-
-	tr2_dst_write_line(&tr2dst_event, &jw.json);
-	jw_release(&jw);
-}
-
-static void maybe_add_string_va(struct json_writer *jw,
-				const char *field_name,
-				const char *fmt, va_list ap)
-{
-	if (fmt && *fmt && ap) {
-		va_list copy_ap;
-		struct strbuf buf = STRBUF_INIT;
-
-		va_copy(copy_ap, ap);
-		strbuf_vaddf(&buf, fmt, copy_ap);
-		va_end(copy_ap);
-
-		jw_object_string(jw, field_name, buf.buf);
-		strbuf_release(&buf);
-		return;
-	}
-
-	if (fmt && *fmt) {
-		jw_object_string(jw, field_name, fmt);
-		return;
-	}
-}
-
-static void fn_error_va_fl(const char *file, int line,
-			   const char *fmt, va_list ap)
-{
-	const char *event_name = "error";
-	struct json_writer jw = JSON_WRITER_INIT;
-
-	jw_object_begin(&jw, 0);
-	event_fmt_prepare(event_name, file, line, NULL, &jw);
-	maybe_add_string_va(&jw, "msg", fmt, ap);
-	/*
-	 * Also emit the format string as a field in case
-	 * post-processors want to aggregate common error
-	 * messages by type without argument fields (such
-	 * as pathnames or branch names) cluttering it up.
-	 */
-	if (fmt && *fmt)
-		jw_object_string(&jw, "fmt", fmt);
-	jw_end(&jw);
-
-	tr2_dst_write_line(&tr2dst_event, &jw.json);
-	jw_release(&jw);
-}
-
-static void fn_command_path_fl(const char *file, int line,
-			       const char *pathname)
-{
-	const char *event_name = "cmd_path";
-	struct json_writer jw = JSON_WRITER_INIT;
-
-	jw_object_begin(&jw, 0);
-	event_fmt_prepare(event_name, file, line, NULL, &jw);
-	jw_object_string(&jw, "path", pathname);
-	jw_end(&jw);
-
-	tr2_dst_write_line(&tr2dst_event, &jw.json);
-	jw_release(&jw);
-}
-
-static void fn_command_verb_fl(const char *file, int line,
-			       const char *command_verb)
-{
-	const char *event_name = "cmd_verb";
-	struct json_writer jw = JSON_WRITER_INIT;
-
-	jw_object_begin(&jw, 0);
-	event_fmt_prepare(event_name, file, line, NULL, &jw);
-	jw_object_string(&jw, "name", command_verb);
-	jw_end(&jw);
-
-	tr2_dst_write_line(&tr2dst_event, &jw.json);
-	jw_release(&jw);
-}
-
-static void fn_alias_fl(const char *file, int line,
-			const char *alias, const char **argv)
-{
-	const char *event_name = "alias";
-	struct json_writer jw = JSON_WRITER_INIT;
-
-	jw_object_begin(&jw, 0);
-	event_fmt_prepare(event_name, file, line, NULL, &jw);
-	jw_object_string(&jw, "alias", alias);
-	jw_object_inline_begin_array(&jw, "argv");
-	jw_array_argv(&jw, argv);
-	jw_end(&jw);
-	jw_end(&jw);
-
-	tr2_dst_write_line(&tr2dst_event, &jw.json);
-	jw_release(&jw);
-}
-
-static void fn_child_start_fl(const char *file, int line,
-			      uint64_t us_elapsed_absolute,
-			      const struct child_process *cmd)
-{
-	const char *event_name = "child_start";
-	struct json_writer jw = JSON_WRITER_INIT;
-	const char *child_class = ((cmd->trace2_child_class) ?
-				   cmd->trace2_child_class : "?");
-
-	jw_object_begin(&jw, 0);
-	event_fmt_prepare(event_name, file, line, NULL, &jw);
-	jw_object_intmax(&jw, "child_id", cmd->trace2_child_id);
-	jw_object_string(&jw, "child_class", child_class);
-	if (cmd->dir)
-		jw_object_string(&jw, "cd", cmd->dir);
-	jw_object_bool(&jw, "use_shell", cmd->use_shell);
-	jw_object_inline_begin_array(&jw, "argv");
-	if (cmd->git_cmd)
-		jw_array_string(&jw, "git");
-	jw_array_argv(&jw, cmd->argv);
-	jw_end(&jw);
-	jw_end(&jw);
-
-	tr2_dst_write_line(&tr2dst_event, &jw.json);
-	jw_release(&jw);
-}
-
-static void fn_child_exit_fl(const char *file, int line,
-			     uint64_t us_elapsed_absolute,
-			     int cid, int code,
-			     uint64_t us_elapsed_child)
-{
-	const char *event_name = "child_exit";
-	struct json_writer jw = JSON_WRITER_INIT;
-	double t_rel = (double)us_elapsed_child / 1000000.0;
-
-	jw_object_begin(&jw, 0);
-	event_fmt_prepare(event_name, file, line, NULL, &jw);
-	jw_object_intmax(&jw, "child_id", cid);
-	jw_object_intmax(&jw, "code", code);
-	jw_object_double(&jw, "t_rel", 6, t_rel);
-	jw_end(&jw);
-
-	tr2_dst_write_line(&tr2dst_event, &jw.json);
-
-	jw_release(&jw);
-}
-
-static void fn_thread_start_fl(const char *file, int line,
-			       uint64_t us_elapsed_absolute)
-{
-	const char *event_name = "thread_start";
-	struct json_writer jw = JSON_WRITER_INIT;
-
-	jw_object_begin(&jw, 0);
-	event_fmt_prepare(event_name, file, line, NULL, &jw);
-	jw_end(&jw);
-
-	tr2_dst_write_line(&tr2dst_event, &jw.json);
-	jw_release(&jw);
-}
-
-static void fn_thread_exit_fl(const char *file, int line,
-			      uint64_t us_elapsed_absolute,
-			      uint64_t us_elapsed_thread)
-{
-	const char *event_name = "thread_exit";
-	struct json_writer jw = JSON_WRITER_INIT;
-	double t_rel = (double)us_elapsed_thread / 1000000.0;
-
-	jw_object_begin(&jw, 0);
-	event_fmt_prepare(event_name, file, line, NULL, &jw);
-	jw_object_double(&jw, "t_rel", 6, t_rel);
-	jw_end(&jw);
-
-	tr2_dst_write_line(&tr2dst_event, &jw.json);
-	jw_release(&jw);
-}
-
-static void fn_exec_fl(const char *file, int line,
-		       uint64_t us_elapsed_absolute,
-		       const char *exe, const char **argv)
-{
-	const char *event_name = "exec";
-	struct json_writer jw = JSON_WRITER_INIT;
-
-	jw_object_begin(&jw, 0);
-	event_fmt_prepare(event_name, file, line, NULL, &jw);
-	if (exe)
-		jw_object_string(&jw, "exe", exe);
-	jw_object_inline_begin_array(&jw, "argv");
-	jw_array_argv(&jw, argv);
-	jw_end(&jw);
-	jw_end(&jw);
-
-	tr2_dst_write_line(&tr2dst_event, &jw.json);
-	jw_release(&jw);
-}
-
-static void fn_exec_result_fl(const char *file, int line,
-			      uint64_t us_elapsed_absolute, int code)
-{
-	const char *event_name = "exec_result";
-	struct json_writer jw = JSON_WRITER_INIT;
-
-	jw_object_begin(&jw, 0);
-	event_fmt_prepare(event_name, file, line, NULL, &jw);
-	jw_object_intmax(&jw, "code", code);
-	jw_end(&jw);
-
-	tr2_dst_write_line(&tr2dst_event, &jw.json);
-	jw_release(&jw);
-}
-
-static void fn_param_fl(const char *file, int line,
-			const char *param, const char *value)
-{
-	const char *event_name = "def_param";
-	struct json_writer jw = JSON_WRITER_INIT;
-
-	jw_object_begin(&jw, 0);
-	event_fmt_prepare(event_name, file, line, NULL, &jw);
-	jw_object_string(&jw, "param", param);
-	jw_object_string(&jw, "value", value);
-	jw_end(&jw);
-
-	tr2_dst_write_line(&tr2dst_event, &jw.json);
-	jw_release(&jw);
-}
-
-static void fn_repo_fl(const char *file, int line,
-		       const struct repository *repo)
-{
-	const char *event_name = "def_repo";
-	struct json_writer jw = JSON_WRITER_INIT;
-
-	jw_object_begin(&jw, 0);
-	event_fmt_prepare(event_name, file, line, repo, &jw);
-	jw_object_string(&jw, "worktree", repo->worktree);
-	jw_end(&jw);
-
-	tr2_dst_write_line(&tr2dst_event, &jw.json);
-	jw_release(&jw);
-}
-
-static void fn_region_enter_printf_va_fl(const char *file, int line,
-					 uint64_t us_elapsed_absolute,
-					 const char *category,
-					 const char *label,
-					 const struct repository *repo,
-					 const char *fmt, va_list ap)
-{
-	const char *event_name = "region_enter";
-	struct tr2tls_thread_ctx *ctx = tr2tls_get_self();
-	if (ctx->nr_open_regions <= tr2env_event_nesting_wanted) {
-		struct json_writer jw = JSON_WRITER_INIT;
-
-		jw_object_begin(&jw, 0);
-		event_fmt_prepare(
-			event_name, file, line, repo, &jw);
-		jw_object_intmax(&jw, "nesting", ctx->nr_open_regions);
-		if (category)
-			jw_object_string(&jw, "category", category);
-		if (label)
-			jw_object_string(&jw, "label", label);
-		maybe_add_string_va(&jw, "msg", fmt, ap);
-		jw_end(&jw);
-
-		tr2_dst_write_line(&tr2dst_event, &jw.json);
-		jw_release(&jw);
-	}
-}
-
-static void fn_region_leave_printf_va_fl(const char *file, int line,
-					 uint64_t us_elapsed_absolute,
-					 uint64_t us_elapsed_region,
-					 const char *category,
-					 const char *label,
-					 const struct repository *repo,
-					 const char *fmt, va_list ap)
-{
-	const char *event_name = "region_leave";
-	struct tr2tls_thread_ctx *ctx = tr2tls_get_self();
-	if (ctx->nr_open_regions <= tr2env_event_nesting_wanted) {
-		struct json_writer jw = JSON_WRITER_INIT;
-		double t_rel = (double)us_elapsed_region / 1000000.0;
-
-		jw_object_begin(&jw, 0);
-		event_fmt_prepare(event_name, file, line, repo, &jw);
-		jw_object_double(&jw, "t_rel", 6, t_rel);
-		jw_object_intmax(&jw, "nesting", ctx->nr_open_regions);
-		if (category)
-			jw_object_string(&jw, "category", category);
-		if (label)
-			jw_object_string(&jw, "label", label);
-		maybe_add_string_va(&jw, "msg", fmt, ap);
-		jw_end(&jw);
-
-		tr2_dst_write_line(&tr2dst_event, &jw.json);
-		jw_release(&jw);
-	}
-}
-
-static void fn_data_fl(const char *file, int line,
-		       uint64_t us_elapsed_absolute,
-		       uint64_t us_elapsed_region,
-		       const char *category,
-		       const struct repository *repo,
-		       const char *key,
-		       const char *value)
-{
-	const char *event_name = "data";
-	struct tr2tls_thread_ctx *ctx = tr2tls_get_self();
-	if (ctx->nr_open_regions <= tr2env_event_nesting_wanted) {
-		struct json_writer jw = JSON_WRITER_INIT;
-		double t_abs = (double)us_elapsed_absolute / 1000000.0;
-		double t_rel = (double)us_elapsed_region / 1000000.0;
-
-		jw_object_begin(&jw, 0);
-		event_fmt_prepare(event_name, file, line, repo, &jw);
-		jw_object_double(&jw, "t_abs", 6, t_abs);
-		jw_object_double(&jw, "t_rel", 6, t_rel);
-		jw_object_intmax(&jw, "nesting", ctx->nr_open_regions);
-		jw_object_string(&jw, "category", category);
-		jw_object_string(&jw, "key", key);
-		jw_object_string(&jw, "value", value);
-		jw_end(&jw);
-
-		tr2_dst_write_line(&tr2dst_event, &jw.json);
-		jw_release(&jw);
-	}
-}
-
-struct tr2_tgt tr2_tgt_event =
-{
-	&tr2dst_event,
-
-	fn_init,
-	fn_term,
-
-	fn_version_fl,
-	fn_start_fl,
-	fn_exit_fl,
-	fn_signal,
-	fn_atexit,
-	fn_error_va_fl,
-	fn_command_path_fl,
-	fn_command_verb_fl,
-	fn_alias_fl,
-	fn_child_start_fl,
-	fn_child_exit_fl,
-	fn_thread_start_fl,
-	fn_thread_exit_fl,
-	fn_exec_fl,
-	fn_exec_result_fl,
-	fn_param_fl,
-	fn_repo_fl,
-	fn_region_enter_printf_va_fl,
-	fn_region_leave_printf_va_fl,
-	fn_data_fl,
-	NULL, /* printf */
-};
diff --git a/trace2/tr2_tgt_normal.c b/trace2/tr2_tgt_normal.c
deleted file mode 100644
index bab32100630273..00000000000000
--- a/trace2/tr2_tgt_normal.c
+++ /dev/null
@@ -1,320 +0,0 @@
-#include "cache.h"
-#include "config.h"
-#include "run-command.h"
-#include "quote.h"
-#include "version.h"
-#include "trace2/tr2_dst.h"
-#include "trace2/tr2_tbuf.h"
-#include "trace2/tr2_tgt.h"
-#include "trace2/tr2_tls.h"
-
-/*
- * This file contains "private/protected" declarations for TRACE2.
- */
-
-static struct tr2_dst tr2dst_normal = { "GIT_TR2", 0, 0, 0 };
-
-/*
- * Set this environment variable to true to omit the "<time> <file>:<line>"
- * fields from each line written to the builtin normal target.
- *
- * Unit tests may want to use this to help with testing.
- */
-#define GIT_TR2_NORMAL_BARE "GIT_TR2_BARE"
-static int tr2env_normal_bare;
-
-#define TR2FMT_NORMAL_FL_WIDTH       (50)
-
-static int fn_init(void)
-{
-	int want = tr2_dst_trace_want(&tr2dst_normal);
-	int want_bare;
-	char *bare;
-
-	if (!want)
-		return want;
-
-	bare = getenv(GIT_TR2_NORMAL_BARE);
-	if (bare && *bare &&
-	    ((want_bare = git_parse_maybe_bool(bare)) != -1))
-		tr2env_normal_bare = want_bare;
-
-	return want;
-}
-
-static void fn_term(void)
-{
-	tr2_dst_trace_disable(&tr2dst_normal);
-}
-
-static void normal_fmt_prepare(const char *file, int line, struct strbuf *buf)
-{
-	strbuf_setlen(buf,0);
-
-	if (!tr2env_normal_bare) {
-		struct tr2_tbuf tb_now;
-
-		tr2_tbuf_current_time(&tb_now);
-		strbuf_addstr(buf, tb_now.buf);
-		strbuf_addch(buf, ' ');
-
-		if (file && *file)
-			strbuf_addf(buf, "%s:%d ", file, line);
-		while (buf->len < TR2FMT_NORMAL_FL_WIDTH)
-			strbuf_addch(buf, ' ');
-	}
-}
-
-static void normal_io_write_fl(const char *file, int line,
-			       const struct strbuf *buf_payload)
-{
-	struct strbuf buf_line = STRBUF_INIT;
-
-	normal_fmt_prepare(file, line, &buf_line);
-	strbuf_addbuf(&buf_line, buf_payload);
-	tr2_dst_write_line(&tr2dst_normal, &buf_line);
-	strbuf_release(&buf_line);
-}
-
-static void fn_version_fl(const char *file, int line)
-{
-	struct strbuf buf_payload = STRBUF_INIT;
-
-	strbuf_addf(&buf_payload, "version %s", git_version_string);
-	normal_io_write_fl(file, line, &buf_payload);
-	strbuf_release(&buf_payload);
-}
-
-static void fn_start_fl(const char *file, int line, const char **argv)
-{
-	struct strbuf buf_payload = STRBUF_INIT;
-
-	strbuf_addstr(&buf_payload, "start ");
-	sq_quote_argv_pretty(&buf_payload, argv);
-	normal_io_write_fl(file, line, &buf_payload);
-	strbuf_release(&buf_payload);
-}
-
-static void fn_exit_fl(const char *file, int line,
-		       uint64_t us_elapsed_absolute, int code)
-{
-	struct strbuf buf_payload = STRBUF_INIT;
-	double elapsed = (double)us_elapsed_absolute / 1000000.0;
-
-	strbuf_addf(&buf_payload, "exit elapsed:%.6f code:%d",
-		    elapsed, code);
-	normal_io_write_fl(file, line, &buf_payload);
-	strbuf_release(&buf_payload);
-}
-
-static void fn_signal(uint64_t us_elapsed_absolute, int signo)
-{
-	struct strbuf buf_payload = STRBUF_INIT;
-	double elapsed = (double)us_elapsed_absolute / 1000000.0;
-
-	strbuf_addf(&buf_payload, "signal elapsed:%.6f code:%d",
-		    elapsed, signo);
-	normal_io_write_fl(__FILE__, __LINE__, &buf_payload);
-	strbuf_release(&buf_payload);
-}
-
-static void fn_atexit(uint64_t us_elapsed_absolute, int code)
-{
-	struct strbuf buf_payload = STRBUF_INIT;
-	double elapsed = (double)us_elapsed_absolute / 1000000.0;
-
-	strbuf_addf(&buf_payload, "atexit elapsed:%.6f code:%d",
-		    elapsed, code);
-	normal_io_write_fl(__FILE__, __LINE__, &buf_payload);
-	strbuf_release(&buf_payload);
-}
-
-static void maybe_append_string_va(struct strbuf *buf,
-				   const char *fmt, va_list ap)
-{
-	if (fmt && *fmt && ap) {
-		va_list copy_ap;
-
-		va_copy(copy_ap, ap);
-		strbuf_vaddf(buf, fmt, copy_ap);
-		va_end(copy_ap);
-		return;
-	}
-
-	if (fmt && *fmt) {
-		strbuf_addstr(buf, fmt);
-		return;
-	}
-}
-
-static void fn_error_va_fl(const char *file, int line,
-			   const char *fmt, va_list ap)
-{
-	struct strbuf buf_payload = STRBUF_INIT;
-
-	strbuf_addstr(&buf_payload, "error ");
-	maybe_append_string_va(&buf_payload, fmt, ap);
-	normal_io_write_fl(file, line, &buf_payload);
-	strbuf_release(&buf_payload);
-}
-
-static void fn_command_path_fl(const char *file, int line,
-			       const char *pathname)
-{
-	struct strbuf buf_payload = STRBUF_INIT;
-
-	strbuf_addf(&buf_payload, "cmd_path %s", pathname);
-	normal_io_write_fl(file, line, &buf_payload);
-	strbuf_release(&buf_payload);
-}
-
-static void fn_command_verb_fl(const char *file, int line,
-			       const char *command_verb)
-{
-	struct strbuf buf_payload = STRBUF_INIT;
-
-	strbuf_addf(&buf_payload, "cmd_verb %s", command_verb);
-	normal_io_write_fl(file, line, &buf_payload);
-	strbuf_release(&buf_payload);
-}
-
-static void fn_alias_fl(const char *file, int line, const char *alias,
-			const char **argv)
-{
-	struct strbuf buf_payload = STRBUF_INIT;
-
-	strbuf_addf(&buf_payload, "alias %s ->", alias);
-	sq_quote_argv_pretty(&buf_payload, argv);
-	normal_io_write_fl(file, line, &buf_payload);
-	strbuf_release(&buf_payload);
-}
-
-static void fn_child_start_fl(const char *file, int line,
-			      uint64_t us_elapsed_absolute,
-			      const struct child_process *cmd)
-{
-	struct strbuf buf_payload = STRBUF_INIT;
-
-	strbuf_addf(&buf_payload, "child_start[%d] ", cmd->trace2_child_id);
-
-	if (cmd->dir) {
-		strbuf_addstr(&buf_payload, " cd");
-		sq_quote_buf_pretty(&buf_payload, cmd->dir);
-		strbuf_addstr(&buf_payload, "; ");
-	}
-
-	/*
-	 * TODO if (cmd->env) { Consider dumping changes to environment. }
-	 * See trace_add_env() in run-command.c as used by original trace.c
-	 */
-
-	if (cmd->git_cmd)
-		strbuf_addstr(&buf_payload, "git");
-	sq_quote_argv_pretty(&buf_payload, cmd->argv);
-
-	normal_io_write_fl(file, line, &buf_payload);
-	strbuf_release(&buf_payload);
-}
-
-static void fn_child_exit_fl(const char *file, int line,
-			     uint64_t us_elapsed_absolute,
-			     int cid, int code,
-			     uint64_t us_elapsed_child)
-{
-	struct strbuf buf_payload = STRBUF_INIT;
-	double elapsed = (double)us_elapsed_child / 1000000.0;
-
-	strbuf_addf(&buf_payload, "child_exit[%d] code:%d elapsed:%.6f",
-		    cid, code, elapsed);
-	normal_io_write_fl(file, line, &buf_payload);
-	strbuf_release(&buf_payload);
-}
-
-static void fn_exec_fl(const char *file, int line,
-		       uint64_t us_elapsed_absolute,
-		       const char *exe, const char **argv)
-{
-	struct strbuf buf_payload = STRBUF_INIT;
-
-	strbuf_addstr(&buf_payload, "exec ");
-	if (exe)
-		strbuf_addstr(&buf_payload, exe);
-	sq_quote_argv_pretty(&buf_payload, argv);
-	normal_io_write_fl(file, line, &buf_payload);
-	strbuf_release(&buf_payload);
-}
-
-static void fn_exec_result_fl(const char *file, int line,
-			      uint64_t us_elapsed_absolute,
-			      int code)
-{
-	struct strbuf buf_payload = STRBUF_INIT;
-
-	strbuf_addf(&buf_payload, "exec_result code:%d", code);
-	if (code > 0)
-		strbuf_addf(&buf_payload, " err:%s", strerror(code));
-	normal_io_write_fl(file, line, &buf_payload);
-	strbuf_release(&buf_payload);
-}
-
-static void fn_param_fl(const char *file, int line, const char *param,
-			const char *value)
-{
-	struct strbuf buf_payload = STRBUF_INIT;
-
-	strbuf_addf(&buf_payload, "def_param %s=%s", param, value);
-	normal_io_write_fl(file, line, &buf_payload);
-	strbuf_release(&buf_payload);
-}
-
-static void fn_repo_fl(const char *file, int line,
-		       const struct repository *repo)
-{
-	struct strbuf buf_payload = STRBUF_INIT;
-
-	strbuf_addstr(&buf_payload, "worktree ");
-	sq_quote_buf_pretty(&buf_payload, repo->worktree);
-	normal_io_write_fl(file, line, &buf_payload);
-	strbuf_release(&buf_payload);
-}
-
-static void fn_printf_va_fl(const char *file, int line,
-			    uint64_t us_elapsed_absolute,
-			    const char *fmt, va_list ap)
-{
-	struct strbuf buf_payload = STRBUF_INIT;
-
-	maybe_append_string_va(&buf_payload, fmt, ap);
-	normal_io_write_fl(file, line, &buf_payload);
-	strbuf_release(&buf_payload);
-}
-
-struct tr2_tgt tr2_tgt_normal =
-{
-	&tr2dst_normal,
-
-	fn_init,
-	fn_term,
-
-	fn_version_fl,
-	fn_start_fl,
-	fn_exit_fl,
-	fn_signal,
-	fn_atexit,
-	fn_error_va_fl,
-	fn_command_path_fl,
-	fn_command_verb_fl,
-	fn_alias_fl,
-	fn_child_start_fl,
-	fn_child_exit_fl,
-	NULL, /* thread_start */
-	NULL, /* thread_exit */
-	fn_exec_fl,
-	fn_exec_result_fl,
-	fn_param_fl,
-	fn_repo_fl,
-	NULL, /* region_enter */
-	NULL, /* region_leave */
-	NULL, /* data */
-	fn_printf_va_fl,
-};
diff --git a/trace2/tr2_tgt_perf.c b/trace2/tr2_tgt_perf.c
deleted file mode 100644
index f2b8089a8c8156..00000000000000
--- a/trace2/tr2_tgt_perf.c
+++ /dev/null
@@ -1,530 +0,0 @@
-#include "cache.h"
-#include "config.h"
-#include "run-command.h"
-#include "quote.h"
-#include "version.h"
-#include "trace2/tr2_dst.h"
-#include "trace2/tr2_sid.h"
-#include "trace2/tr2_tbuf.h"
-#include "trace2/tr2_tgt.h"
-#include "trace2/tr2_tls.h"
-
-/*
- * This file contains "private/protected" declarations for TRACE2.
- */
-
-static struct tr2_dst tr2dst_perf   = { "GIT_TR2_PERF", 0, 0, 0 };
-
-/*
- * Set this environment variable to true to omit the "<time> <file>:<line>"
- * fields from each line written to the builtin performance target.
- *
- * Unit tests may want to use this to help with testing.
- */
-#define GIT_TR2_PERF_BARE "GIT_TR2_BARE"
-static int tr2env_perf_bare;
-
-#define TR2FMT_PERF_FL_WIDTH       (50)
-#define TR2FMT_PERF_MAX_EVENT_NAME (12)
-#define TR2FMT_PERF_REPO_WIDTH     (4)
-#define TR2FMT_PERF_CATEGORY_WIDTH (10)
-
-#define TR2_DOTS_BUFFER_SIZE (100)
-#define TR2_INDENT (2)
-#define TR2_INDENT_LENGTH(ctx) (((ctx)->nr_open_regions - 1) * TR2_INDENT)
-
-static struct strbuf dots = STRBUF_INIT;
-
-static int fn_init(void)
-{
-	int want = tr2_dst_trace_want(&tr2dst_perf);
-	int want_bare;
-	char *bare;
-
-	if (!want)
-		return want;
-
-	strbuf_addchars(&dots, '.', TR2_DOTS_BUFFER_SIZE);
-
-	bare = getenv(GIT_TR2_PERF_BARE);
-	if (bare && *bare &&
-	    ((want_bare = git_parse_maybe_bool(bare)) != -1))
-		tr2env_perf_bare = want_bare;
-
-	return want;
-}
-
-static void fn_term(void)
-{
-	tr2_dst_trace_disable(&tr2dst_perf);
-
-	strbuf_release(&dots);
-}
-
-/*
- * Format trace line prefix in human-readable classic format for
- * the performance target:
- *     "[<time> [<file>:<line>] <bar> <nr_parents> <bar>]
- *         <thread_name> <bar> <event_name> <bar> [<repo>] <bar>
- *         [<elapsed_absolute>] [<elapsed_relative>] <bar>
- *         [<category>] <bar> [<dots>] "
- */
-static void perf_fmt_prepare(
-	const char *event_name, struct tr2tls_thread_ctx *ctx,
-	const char *file, int line, const struct repository *repo,
-	uint64_t *p_us_elapsed_absolute, uint64_t *p_us_elapsed_relative,
-	const char *category, struct strbuf *buf)
-{
-	int len;
-
-	strbuf_setlen(buf,0);
-
-	if (!tr2env_perf_bare) {
-
-		struct tr2_tbuf tb_now;
-
-		tr2_tbuf_current_time(&tb_now);
-		strbuf_addstr(buf, tb_now.buf);
-		strbuf_addch(buf, ' ');
-
-		if (file && *file)
-			strbuf_addf(buf, "%s:%d ", file, line);
-		while (buf->len < TR2FMT_PERF_FL_WIDTH)
-			strbuf_addch(buf, ' ');
-
-		strbuf_addf(buf, "| d%d | ", tr2_sid_depth());
-	}
-
-	strbuf_addf(buf, "%-*s | %-*s | ",
-		    TR2_MAX_THREAD_NAME, ctx->thread_name.buf,
-		    TR2FMT_PERF_MAX_EVENT_NAME, event_name);
-
-	len = buf->len + TR2FMT_PERF_REPO_WIDTH;
-	if (repo)
-		strbuf_addf(buf, "r%d ", repo->trace2_repo_id);
-	while (buf->len < len)
-		strbuf_addch(buf, ' ' );
-	strbuf_addstr(buf, "| ");
-
-	if (p_us_elapsed_absolute)
-		strbuf_addf(buf, "%9.6f | ",
-			    ((double)(*p_us_elapsed_absolute)) / 1000000.0);
-	else
-		strbuf_addf(buf, "%9s | ", " ");
-
-	if (p_us_elapsed_relative)
-		strbuf_addf(buf, "%9.6f | ",
-			    ((double)(*p_us_elapsed_relative)) / 1000000.0);
-	else
-		strbuf_addf(buf, "%9s | ", " ");
-		
-	strbuf_addf(buf, "%-*s | ", TR2FMT_PERF_CATEGORY_WIDTH,
-		    (category ? category : ""));
-
-	if (ctx->nr_open_regions > 0) {
-		int len_indent = TR2_INDENT_LENGTH(ctx);
-		while (len_indent > dots.len) {
-			strbuf_addf(buf, "%s", dots.buf);
-			len_indent -= dots.len;
-		}
-		strbuf_addf(buf, "%.*s", len_indent, dots.buf);
-	}
-}
-
-static void perf_io_write_fl(
-	const char *file, int line,
-	const char *event_name,
-	const struct repository *repo,
-	uint64_t *p_us_elapsed_absolute,
-	uint64_t *p_us_elapsed_relative,
-	const char *category,
-	const struct strbuf *buf_payload)
-{
-	struct tr2tls_thread_ctx *ctx = tr2tls_get_self();
-	struct strbuf buf_line = STRBUF_INIT;
-
-	perf_fmt_prepare(event_name, ctx, file, line, repo,
-			 p_us_elapsed_absolute, p_us_elapsed_relative,
-			 category, &buf_line);
-	strbuf_addbuf(&buf_line, buf_payload);
-	tr2_dst_write_line(&tr2dst_perf, &buf_line);
-	strbuf_release(&buf_line);
-}
-
-static void fn_version_fl(const char *file, int line)
-{
-	const char *event_name = "version";
-	struct strbuf buf_payload = STRBUF_INIT;
-
-	strbuf_addf(&buf_payload, "%s", git_version_string);
-
-	perf_io_write_fl(file, line, event_name, NULL,
-			 NULL, NULL, NULL,
-			 &buf_payload);
-	strbuf_release(&buf_payload);
-}
-
-static void fn_start_fl(const char *file, int line, const char **argv)
-{
-	const char *event_name = "start";
-	struct strbuf buf_payload = STRBUF_INIT;
-
-	sq_quote_argv_pretty(&buf_payload, argv);
-
-	perf_io_write_fl(file, line, event_name, NULL,
-			 NULL, NULL, NULL,
-			 &buf_payload);
-	strbuf_release(&buf_payload);
-}
-
-static void fn_exit_fl(const char *file, int line,
-		       uint64_t us_elapsed_absolute, int code)
-{
-	const char *event_name = "exit";
-	struct strbuf buf_payload = STRBUF_INIT;
-
-	strbuf_addf(&buf_payload, "code:%d", code);
-
-	perf_io_write_fl(file, line, event_name, NULL,
-			 &us_elapsed_absolute, NULL, NULL,
-			 &buf_payload);
-	strbuf_release(&buf_payload);
-}
-
-static void fn_signal(uint64_t us_elapsed_absolute, int signo)
-{
-	const char *event_name = "signal";
-	struct strbuf buf_payload = STRBUF_INIT;
-
-	strbuf_addf(&buf_payload, "signo:%d", signo);
-
-	perf_io_write_fl(__FILE__, __LINE__, event_name, NULL,
-			 &us_elapsed_absolute, NULL, NULL,
-			 &buf_payload);
-	strbuf_release(&buf_payload);
-}
-
-static void fn_atexit(uint64_t us_elapsed_absolute, int code)
-{
-	const char *event_name = "atexit";
-	struct strbuf buf_payload = STRBUF_INIT;
-
-	strbuf_addf(&buf_payload, "code:%d", code);
-
-	perf_io_write_fl(__FILE__, __LINE__, event_name, NULL,
-			 &us_elapsed_absolute, NULL, NULL,
-			 &buf_payload);
-	strbuf_release(&buf_payload);
-}
-
-static void maybe_append_string_va(struct strbuf *buf,
-				   const char *fmt, va_list ap)
-{
-	if (fmt && *fmt && ap) {
-		va_list copy_ap;
-
-		va_copy(copy_ap, ap);
-		strbuf_vaddf(buf, fmt, copy_ap);
-		va_end(copy_ap);
-		return;
-	}
-
-	if (fmt && *fmt) {
-		strbuf_addstr(buf, fmt);
-		return;
-	}
-}
-
-static void fn_error_va_fl(const char *file, int line,
-			   const char *fmt, va_list ap)
-{
-	const char *event_name = "error";
-	struct strbuf buf_payload = STRBUF_INIT;
-
-	maybe_append_string_va(&buf_payload, fmt, ap);
-
-	perf_io_write_fl(file, line, event_name, NULL,
-			 NULL, NULL, NULL,
-			 &buf_payload);
-	strbuf_release(&buf_payload);
-}
-
-static void fn_command_path_fl(const char *file, int line,
-			       const char *pathname)
-{
-	const char *event_name = "cmd_path";
-	struct strbuf buf_payload = STRBUF_INIT;
-
-	strbuf_addstr(&buf_payload, pathname);
-
-	perf_io_write_fl(file, line, event_name, NULL,
-			 NULL, NULL, NULL,
-			 &buf_payload);
-	strbuf_release(&buf_payload);
-}
-
-static void fn_command_verb_fl(const char *file, int line,
-			       const char *command_verb)
-{
-	const char *event_name = "cmd_verb";
-	struct strbuf buf_payload = STRBUF_INIT;
-
-	strbuf_addstr(&buf_payload, command_verb);
-
-	perf_io_write_fl(file, line, event_name, NULL,
-			 NULL, NULL, NULL,
-			 &buf_payload);
-	strbuf_release(&buf_payload);
-}
-
-static void fn_alias_fl(const char *file, int line, const char *alias,
-			const char **argv)
-{
-	const char *event_name = "alias";
-	struct strbuf buf_payload = STRBUF_INIT;
-
-	strbuf_addf(&buf_payload, "alias:%s argv:", alias);
-	sq_quote_argv_pretty(&buf_payload, argv);
-
-	perf_io_write_fl(file, line, event_name, NULL,
-			 NULL, NULL, NULL,
-			 &buf_payload);
-	strbuf_release(&buf_payload);
-}
-
-static void fn_child_start_fl(const char *file, int line,
-			      uint64_t us_elapsed_absolute,
-			      const struct child_process *cmd)
-{
-	const char *event_name = "child_start";
-	struct strbuf buf_payload = STRBUF_INIT;
-	const char *child_class = ((cmd->trace2_child_class) ?
-				   cmd->trace2_child_class : "?");
-
-	strbuf_addf(&buf_payload, "[ch%d] class:%s",
-		    cmd->trace2_child_id, child_class);
-
-	if (cmd->dir) {
-		strbuf_addstr(&buf_payload, " cd:");
-		sq_quote_buf_pretty(&buf_payload, cmd->dir);
-	}
-
-	strbuf_addstr(&buf_payload, " argv:");
-	if (cmd->git_cmd)
-		strbuf_addstr(&buf_payload, " git");
-	sq_quote_argv_pretty(&buf_payload, cmd->argv);
-
-	perf_io_write_fl(file, line, event_name, NULL,
-			 &us_elapsed_absolute, NULL, NULL,
-			 &buf_payload);
-	strbuf_release(&buf_payload);
-}
-
-static void fn_child_exit_fl(const char *file, int line,
-			     uint64_t us_elapsed_absolute,
-			     int cid, int code, uint64_t us_elapsed_child)
-{
-	const char *event_name = "child_exit";
-	struct strbuf buf_payload = STRBUF_INIT;
-
-	strbuf_addf(&buf_payload, "[ch%d] code:%d", cid, code);
-
-	perf_io_write_fl(file, line, event_name, NULL,
-			 &us_elapsed_absolute, &us_elapsed_child, NULL,
-			 &buf_payload);
-	strbuf_release(&buf_payload);
-}
-
-static void fn_thread_start_fl(const char *file, int line,
-				     uint64_t us_elapsed_absolute)
-{
-	const char *event_name = "thread_start";
-	struct strbuf buf_payload = STRBUF_INIT;
-
-	perf_io_write_fl(file, line, event_name, NULL,
-			 &us_elapsed_absolute, NULL, NULL,
-			 &buf_payload);
-	strbuf_release(&buf_payload);
-}
-
-static void fn_thread_exit_fl(const char *file, int line,
-			      uint64_t us_elapsed_absolute,
-			      uint64_t us_elapsed_thread)
-{
-	const char *event_name = "thread_exit";
-	struct strbuf buf_payload = STRBUF_INIT;
-
-	perf_io_write_fl(file, line, event_name, NULL,
-			 &us_elapsed_absolute, &us_elapsed_thread, NULL,
-			 &buf_payload);
-	strbuf_release(&buf_payload);
-}
-
-static void fn_exec_fl(const char *file, int line,
-		       uint64_t us_elapsed_absolute,
-		       const char *exe, const char **argv)
-{
-	const char *event_name = "exec";
-	struct strbuf buf_payload = STRBUF_INIT;
-
-	strbuf_addstr(&buf_payload, "argv:");
-	if (exe)
-		strbuf_addf(&buf_payload, " %s", exe);
-	sq_quote_argv_pretty(&buf_payload, argv);
-
-	perf_io_write_fl(file, line, event_name, NULL,
-			 &us_elapsed_absolute, NULL, NULL,
-			 &buf_payload);
-	strbuf_release(&buf_payload);
-}
-
-static void fn_exec_result_fl(const char *file, int line,
-			      uint64_t us_elapsed_absolute,
-			      int code)
-{
-	const char *event_name = "exec_result";
-	struct strbuf buf_payload = STRBUF_INIT;
-
-	strbuf_addf(&buf_payload, "code:%d", code);
-	if (code > 0)
-		strbuf_addf(&buf_payload, " err:%s", strerror(code));
-
-	perf_io_write_fl(file, line, event_name, NULL,
-			 &us_elapsed_absolute, NULL, NULL,
-			 &buf_payload);
-	strbuf_release(&buf_payload);
-}
-
-static void fn_param_fl(const char *file, int line,
-			const char *param, const char *value)
-{
-	const char *event_name = "def_param";
-	struct strbuf buf_payload = STRBUF_INIT;
-
-	strbuf_addf(&buf_payload, "%s:%s", param, value);
-
-	perf_io_write_fl(file, line, event_name, NULL,
-			 NULL, NULL, NULL,
-			 &buf_payload);
-	strbuf_release(&buf_payload);
-}
-
-static void fn_repo_fl(const char *file, int line,
-		       const struct repository *repo)
-{
-	const char *event_name = "def_repo";
-	struct strbuf buf_payload = STRBUF_INIT;
-
-	strbuf_addstr(&buf_payload, "worktree:");
-	sq_quote_buf_pretty(&buf_payload, repo->worktree);
-
-	perf_io_write_fl(file, line, event_name, repo,
-			 NULL, NULL, NULL,
-			 &buf_payload);
-	strbuf_release(&buf_payload);
-}
-
-static void fn_region_enter_printf_va_fl(const char *file, int line,
-					 uint64_t us_elapsed_absolute,
-					 const char *category,
-					 const char *label,
-					 const struct repository *repo,
-					 const char *fmt, va_list ap)
-{
-	const char *event_name = "region_enter";
-	struct strbuf buf_payload = STRBUF_INIT;
-
-	if (label)
-		strbuf_addf(&buf_payload, "label:%s ", label);
-	maybe_append_string_va(&buf_payload, fmt, ap);
-
-	perf_io_write_fl(file, line, event_name, repo,
-			 &us_elapsed_absolute, NULL, category,
-			 &buf_payload);
-	strbuf_release(&buf_payload);
-}
-
-static void fn_region_leave_printf_va_fl(const char *file, int line,
-					 uint64_t us_elapsed_absolute,
-					 uint64_t us_elapsed_region,
-					 const char *category,
-					 const char *label,
-					 const struct repository *repo,
-					 const char *fmt, va_list ap)
-{
-	const char *event_name = "region_leave";
-	struct strbuf buf_payload = STRBUF_INIT;
-
-	if (label)
-		strbuf_addf(&buf_payload, "label:%s ", label);
-	maybe_append_string_va(&buf_payload, fmt, ap);
-
-	perf_io_write_fl(file, line, event_name, repo,
-			 &us_elapsed_absolute, &us_elapsed_region, category,
-			 &buf_payload);
-	strbuf_release(&buf_payload);
-}
-
-static void fn_data_fl(const char *file, int line,
-		       uint64_t us_elapsed_absolute,
-		       uint64_t us_elapsed_region,
-		       const char *category,
-		       const struct repository *repo,
-		       const char *key,
-		       const char *value)
-{
-	const char *event_name = "data";
-	struct strbuf buf_payload = STRBUF_INIT;
-
-	strbuf_addf(&buf_payload, "%s:%s", key, value);
-
-	perf_io_write_fl(file, line, event_name, repo,
-			 &us_elapsed_absolute, &us_elapsed_region, category,
-			 &buf_payload);
-	strbuf_release(&buf_payload);
-}
-
-static void fn_printf_va_fl(const char *file, int line,
-			    uint64_t us_elapsed_absolute,
-			    const char *fmt, va_list ap)
-{
-	const char *event_name = "printf";
-	struct strbuf buf_payload = STRBUF_INIT;
-
-	maybe_append_string_va(&buf_payload, fmt, ap);
-
-	perf_io_write_fl(file, line, event_name, NULL,
-			 &us_elapsed_absolute, NULL, NULL,
-			 &buf_payload);
-	strbuf_release(&buf_payload);
-}
-
-struct tr2_tgt tr2_tgt_perf =
-{
-	&tr2dst_perf,
-
-	fn_init,
-	fn_term,
-
-	fn_version_fl,
-	fn_start_fl,
-	fn_exit_fl,
-	fn_signal,
-	fn_atexit,
-	fn_error_va_fl,
-	fn_command_path_fl,
-	fn_command_verb_fl,
-	fn_alias_fl,
-	fn_child_start_fl,
-	fn_child_exit_fl,
-	fn_thread_start_fl,
-	fn_thread_exit_fl,
-	fn_exec_fl,
-	fn_exec_result_fl,
-	fn_param_fl,
-	fn_repo_fl,
-	fn_region_enter_printf_va_fl,
-	fn_region_leave_printf_va_fl,
-	fn_data_fl,
-	fn_printf_va_fl,
-};
diff --git a/trace2/tr2_tls.c b/trace2/tr2_tls.c
deleted file mode 100644
index 4d5747951e5e43..00000000000000
--- a/trace2/tr2_tls.c
+++ /dev/null
@@ -1,170 +0,0 @@
-#include "cache.h"
-#include "thread-utils.h"
-#include "trace2/tr2_tls.h"
-
-/*
- * This file contains "private/protected" routines for TRACE2.
- */
-
-/*
- * Initialize size of the thread stack for nested regions.
- * This is used to store nested region start times.  Note that
- * this stack is per-thread and not per-trace-key.
- */
-#define TR2_REGION_NESTING_INITIAL_SIZE (100)
-
-static struct tr2tls_thread_ctx *tr2tls_thread_main;
-static uint64_t tr2tls_us_start_main;
-
-static pthread_mutex_t tr2tls_mutex;
-static pthread_key_t tr2tls_key;
-
-static int tr2_next_thread_id; /* modify under lock */
-
-struct tr2tls_thread_ctx *tr2tls_create_self(const char *thread_name)
-{
-	uint64_t us_now = getnanotime() / 1000;
-	struct tr2tls_thread_ctx *ctx = xcalloc(1, sizeof(*ctx));
-
-	/*
-	 * Implicitly "tr2tls_push_self()" to capture the thread's start
-	 * time in array_us_start[0].  For the main thread this gives us the
-	 * application run time.
-	 */
-	ctx->alloc = TR2_REGION_NESTING_INITIAL_SIZE;
-	ctx->array_us_start = (uint64_t*)xcalloc(ctx->alloc, sizeof(uint64_t));
-	ctx->array_us_start[ctx->nr_open_regions++] = us_now;
-
-	ctx->thread_id = tr2tls_locked_increment(&tr2_next_thread_id);
-	
-	strbuf_init(&ctx->thread_name, 0);
-	if (ctx->thread_id)
-		strbuf_addf(&ctx->thread_name, "th%02d:", ctx->thread_id);
-	strbuf_addstr(&ctx->thread_name, thread_name);
-	if (ctx->thread_name.len > TR2_MAX_THREAD_NAME)
-		strbuf_setlen(&ctx->thread_name, TR2_MAX_THREAD_NAME);
-
-	pthread_setspecific(tr2tls_key, ctx);
-
-	return ctx;
-}
-
-struct tr2tls_thread_ctx *tr2tls_get_self(void)
-{
-	struct tr2tls_thread_ctx * ctx = pthread_getspecific(tr2tls_key);
-
-	/*
-	 * If the thread-proc did not call trace2_thread_start(), we won't
-	 * have any TLS data associated with the current thread.  Fix it
-	 * here and silently continue.
-	 */
-	if (!ctx)
-		ctx = tr2tls_create_self("unknown");
-
-	return ctx;
-}
-
-int tr2tls_is_main_thread(void)
-{
-	struct tr2tls_thread_ctx * ctx;
-
-	ctx = tr2tls_get_self();
-
-	return ctx == tr2tls_thread_main;
-}
-
-void tr2tls_unset_self(void)
-{
-	struct tr2tls_thread_ctx * ctx;
-
-	ctx = tr2tls_get_self();
-
-	pthread_setspecific(tr2tls_key, NULL);
-
-	free(ctx->array_us_start);
-	free(ctx);
-}
-
-void tr2tls_push_self(uint64_t us_now)
-{
-	struct tr2tls_thread_ctx *ctx = tr2tls_get_self();
-
-	ALLOC_GROW(ctx->array_us_start, ctx->nr_open_regions + 1, ctx->alloc);
-	ctx->array_us_start[ctx->nr_open_regions++] = us_now;
-}
-
-void tr2tls_pop_self(void)
-{
-	struct tr2tls_thread_ctx *ctx = tr2tls_get_self();
-
-	if (!ctx->nr_open_regions)
-		BUG("no open regions in thread '%s'", ctx->thread_name.buf);
-
-	ctx->nr_open_regions--;
-}
-
-void tr2tls_pop_unwind_self(void)
-{
-	struct tr2tls_thread_ctx *ctx = tr2tls_get_self();
-
-	while (ctx->nr_open_regions > 1)
-		tr2tls_pop_self();
-}
-
-uint64_t tr2tls_region_elasped_self(uint64_t us)
-{
-	struct tr2tls_thread_ctx *ctx;
-	uint64_t us_start;
-
-	ctx = tr2tls_get_self();
-	if (!ctx->nr_open_regions)
-		return 0;
-	
-	us_start = ctx->array_us_start[ctx->nr_open_regions - 1];
-
-	return us - us_start;
-}
-
-uint64_t tr2tls_absolute_elapsed(uint64_t us)
-{
-	if (!tr2tls_thread_main)
-		return 0;
-
-	return us - tr2tls_us_start_main;
-}
-
-void tr2tls_init(void)
-{
-	pthread_key_create(&tr2tls_key, NULL);
-	init_recursive_mutex(&tr2tls_mutex);
-
-	tr2tls_thread_main = tr2tls_create_self("main");
-	/*
-	 * Keep a copy of the absolute start time of the main thread
-	 * in a fixed variable since other threads need to access it.
-	 * This also eliminates the need to lock accesses to the main
-	 * thread's array (because of reallocs).
-	 */
-	tr2tls_us_start_main = tr2tls_thread_main->array_us_start[0];
-}
-
-void tr2tls_release(void)
-{
-	tr2tls_unset_self();
-	tr2tls_thread_main = NULL;
-
-	pthread_mutex_destroy(&tr2tls_mutex);
-	pthread_key_delete(tr2tls_key);
-}
-
-int tr2tls_locked_increment(int *p)
-{
-	int current_value;
-
-	pthread_mutex_lock(&tr2tls_mutex);
-	current_value = *p;
-	*p = current_value + 1;
-	pthread_mutex_unlock(&tr2tls_mutex);
-
-	return current_value;
-}
diff --git a/trace2/tr2_tls.h b/trace2/tr2_tls.h
deleted file mode 100644
index 145fa7e462ed77..00000000000000
--- a/trace2/tr2_tls.h
+++ /dev/null
@@ -1,99 +0,0 @@
-#ifndef TR2_TLS_H
-#define TR2_TLS_H
-
-/*
- * This file contains "private/protected" declarations for TRACE2.
- */
-
-/*
- * Arbitry limit for thread names for column alignment.
- */
-#define TR2_MAX_THREAD_NAME (24)
-
-struct tr2tls_thread_ctx {
-	struct strbuf thread_name;
-	uint64_t *array_us_start;
-	int alloc;
-	int nr_open_regions; /* plays role of "nr" in ALLOC_GROW */
-	int thread_id;
-};
-
-/*
- * Create TLS data for the current thread.  This gives us a place to
- * put per-thread data, such as thread start time, function nesting
- * and a per-thread label for our messages.
- *
- * We assume the first thread is "main".  Other threads are given
- * non-zero thread-ids to help distinguish messages from concurrent
- * threads.
- *
- * Truncate the thread name if necessary to help with column alignment
- * in printf-style messages.
- *
- * In this and all following functions the term "self" refers to the
- * current thread.
- */
-struct tr2tls_thread_ctx *tr2tls_create_self(const char *thread_name);
-
-/*
- * Get our TLS data.
- */
-struct tr2tls_thread_ctx *tr2tls_get_self(void);
-
-/*
- * return true if the current thread is the main thread.
- */
-int tr2tls_is_main_thread(void);
-
-/*
- * Free our TLS data.
- */
-void tr2tls_unset_self(void);
-
-/*
- * Begin a new nested region and remember the start time.
- */
-void tr2tls_push_self(uint64_t us_now);
-
-/*
- * End the innermost nested region.
- */
-void tr2tls_pop_self(void);
-
-/*
- * Pop any extra (above the first) open regions on the current
- * thread and discard.  During a thread-exit, we should only
- * have region[0] that was pushed in trace2_thread_start() if
- * the thread exits normally.
- */
-void tr2tls_pop_unwind_self(void);
-
-/*
- * Compute the elapsed time since the innermost region in the
- * current thread started and the given time (usually now).
- */
-uint64_t tr2tls_region_elasped_self(uint64_t us);
-
-/*
- * Compute the elapsed time since the main thread started
- * and the given time (usually now).  This is assumed to
- * be the absolute run time of the process.
- */
-uint64_t tr2tls_absolute_elapsed(uint64_t us);
-
-/*
- * Initialize the tr2 TLS system.
- */
-void tr2tls_init(void);
-
-/*
- * Free all tr2 TLS resources.
- */
-void tr2tls_release(void);
-
-/*
- * Protected increment of an integer.
- */
-int tr2tls_locked_increment(int *p);
-
-#endif /* TR2_TLS_H */
diff --git a/usage.c b/usage.c
index 3f57bac0d52387..cc803336bd5e67 100644
--- a/usage.c
+++ b/usage.c
@@ -22,48 +22,17 @@ void vreportf(const char *prefix, const char *err, va_list params)
 static NORETURN void usage_builtin(const char *err, va_list params)
 {
 	vreportf("usage: ", err, params);
-
-	/*
-	 * For command instances where we detected a syntax *before* the
-	 * command dispatch in cmd_main(), we don't know what verb to
-	 * report.  Force it to "_usage_" to facilitate post-processing.
-	 */
-	trace2_cmd_verb("_usage_");
-
-	/*
-	 * Currently, the (err, params) are usually just the static usage
-	 * string which isn't very useful here.  Usually, the call site
-	 * manually calls fprintf(stderr,...) with the actual detailed
-	 * syntax error before calling usage().
-	 *
-	 * TODO It would be nice to update the call sites to pass both
-	 * the static usage string and the detailed error message.
-	 */
-
 	exit(129);
 }
 
 static NORETURN void die_builtin(const char *err, va_list params)
 {
-	/*
-	 * We call this trace2 function first and expect it to va_copy 'params'
-	 * before using it (because an 'ap' can only be walked once).
-	 */
-	trace2_cmd_error_va(err, params);
-
 	vreportf("fatal: ", err, params);
-
 	exit(128);
 }
 
 static void error_builtin(const char *err, va_list params)
 {
-	/*
-	 * We call this trace2 function first and expect it to va_copy 'params'
-	 * before using it (because an 'ap' can only be walked once).
-	 */
-	trace2_cmd_error_va(err, params);
-
 	vreportf("error: ", err, params);
 }
 

From c849c28e3c35b3de042b49c69babc01c97d969a2 Mon Sep 17 00:00:00 2001
From: Jeff Hostetler <jeffhost@microsoft.com>
Date: Thu, 30 Aug 2018 12:53:37 -0400
Subject: [PATCH 09/25] trace2: (V3) create new combined trace facility

Create a new unified tracing facility for git.  The eventual intent is to
replace the current trace_printf* and trace_performance* routines with a
unified set of git_trace2* routines.

In addition to the usual printf-style API, trace2 provides higer-level
event verbs with fixed-fields allowing structured data to be written.
This makes post-processing and analysis easier for external tools.

Trace2 defines 3 output targets.  These are set using the environment
variables "GIT_TR2", "GIT_TR2_PERF", and "GIT_TR2_EVENT".  These may be
set to "1" or to an absolute pathname (just like the current GIT_TRACE).

* GIT_TR2 is intended to be a replacement for GIT_TRACE and logs command
  summary data.

* GIT_TR2_PERF is intended as a replacement for GIT_TRACE_PERFORMANCE.
  It extends the output with columns for the command process, thread,
  repo, absolute and relative elapsed times.  It reports events for
  child process start/stop, thread start/stop, and per-thread function
  nesting.

* GIT_TR2_EVENT is a new structured format. It writes event data as a
  series of JSON records.

Calls to trace2 functions log to any of the 3 output targets enabled
without the need to call different trace_printf* or trace_performance*
routines.

Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
---
 Makefile                      |  10 +
 cache.h                       |   1 +
 common-main.c                 |  12 +-
 compat/mingw.c                |  11 +-
 compat/mingw.h                |   3 +-
 config.c                      |   2 +
 exec-cmd.c                    |   2 +
 git-compat-util.h             |   7 +
 git.c                         |  47 +-
 remote-curl.c                 |   7 +
 repository.c                  |   2 +
 repository.h                  |   3 +
 run-command.c                 |  53 ++-
 run-command.h                 |  11 +-
 sh-i18n--envsubst.c           |   3 +
 t/helper/test-parse-options.c |   3 +
 t/helper/test-tool.c          |   3 +
 t/t0001-init.sh               |   1 +
 trace2.c                      | 817 ++++++++++++++++++++++++++++++++++
 trace2.h                      | 390 ++++++++++++++++
 trace2/tr2_cfg.c              |  92 ++++
 trace2/tr2_cfg.h              |  23 +
 trace2/tr2_dst.c              |  87 ++++
 trace2/tr2_dst.h              |  34 ++
 trace2/tr2_sid.c              |  71 +++
 trace2/tr2_sid.h              |  22 +
 trace2/tr2_tbuf.c             |  33 ++
 trace2/tr2_tbuf.h             |  20 +
 trace2/tr2_tgt.h              | 130 ++++++
 trace2/tr2_tgt_event.c        | 590 ++++++++++++++++++++++++
 trace2/tr2_tgt_normal.c       | 335 ++++++++++++++
 trace2/tr2_tgt_perf.c         | 574 ++++++++++++++++++++++++
 trace2/tr2_tls.c              | 170 +++++++
 trace2/tr2_tls.h              |  99 ++++
 trace2/tr2_verb.c             |  34 ++
 trace2/tr2_verb.h             |  28 ++
 usage.c                       |  31 ++
 37 files changed, 3750 insertions(+), 11 deletions(-)
 create mode 100644 trace2.c
 create mode 100644 trace2.h
 create mode 100644 trace2/tr2_cfg.c
 create mode 100644 trace2/tr2_cfg.h
 create mode 100644 trace2/tr2_dst.c
 create mode 100644 trace2/tr2_dst.h
 create mode 100644 trace2/tr2_sid.c
 create mode 100644 trace2/tr2_sid.h
 create mode 100644 trace2/tr2_tbuf.c
 create mode 100644 trace2/tr2_tbuf.h
 create mode 100644 trace2/tr2_tgt.h
 create mode 100644 trace2/tr2_tgt_event.c
 create mode 100644 trace2/tr2_tgt_normal.c
 create mode 100644 trace2/tr2_tgt_perf.c
 create mode 100644 trace2/tr2_tls.c
 create mode 100644 trace2/tr2_tls.h
 create mode 100644 trace2/tr2_verb.c
 create mode 100644 trace2/tr2_verb.h

diff --git a/Makefile b/Makefile
index 37c6bc9d76fb97..f952dc2124a8fb 100644
--- a/Makefile
+++ b/Makefile
@@ -1000,6 +1000,16 @@ LIB_OBJS += tempfile.o
 LIB_OBJS += thread-utils.o
 LIB_OBJS += tmp-objdir.o
 LIB_OBJS += trace.o
+LIB_OBJS += trace2.o
+LIB_OBJS += trace2/tr2_cfg.o
+LIB_OBJS += trace2/tr2_dst.o
+LIB_OBJS += trace2/tr2_sid.o
+LIB_OBJS += trace2/tr2_tbuf.o
+LIB_OBJS += trace2/tr2_tgt_event.o
+LIB_OBJS += trace2/tr2_tgt_normal.o
+LIB_OBJS += trace2/tr2_tgt_perf.o
+LIB_OBJS += trace2/tr2_tls.o
+LIB_OBJS += trace2/tr2_verb.o
 LIB_OBJS += trailer.o
 LIB_OBJS += transport.o
 LIB_OBJS += transport-helper.o
diff --git a/cache.h b/cache.h
index dfed668e0dbdd1..cf849fe505cd59 100644
--- a/cache.h
+++ b/cache.h
@@ -9,6 +9,7 @@
 #include "gettext.h"
 #include "convert.h"
 #include "trace.h"
+#include "trace2.h"
 #include "string-list.h"
 #include "pack-revindex.h"
 #include "hash.h"
diff --git a/common-main.c b/common-main.c
index 3728f66b4cce80..6dbdc4adf272ef 100644
--- a/common-main.c
+++ b/common-main.c
@@ -25,12 +25,18 @@ static void restore_sigpipe_to_default(void)
 
 int main(int argc, const char **argv)
 {
+	int result;
+
 	/*
 	 * Always open file descriptors 0/1/2 to avoid clobbering files
 	 * in die().  It also avoids messing up when the pipes are dup'ed
 	 * onto stdin/stdout/stderr in the child processes we spawn.
 	 */
 	sanitize_stdfds();
+	restore_sigpipe_to_default();
+
+	trace2_initialize();
+	trace2_cmd_start(argv);
 
 	git_resolve_executable_dir(argv[0]);
 
@@ -40,7 +46,9 @@ int main(int argc, const char **argv)
 
 	attr_start();
 
-	restore_sigpipe_to_default();
+	result = cmd_main(argc, argv);
+
+	trace2_cmd_exit(result);
 
-	return cmd_main(argc, argv);
+	return result;
 }
diff --git a/compat/mingw.c b/compat/mingw.c
index 29c6c2cae9b444..c695e5a5a07c91 100644
--- a/compat/mingw.c
+++ b/compat/mingw.c
@@ -1945,6 +1945,7 @@ static int try_shell_exec(const char *cmd, char *const *argv)
 		return 0;
 	prog = path_lookup(interpr, 1);
 	if (prog) {
+		int exec_id;
 		int argc = 0;
 #ifndef _MSC_VER
 		const
@@ -1954,13 +1955,16 @@ static int try_shell_exec(const char *cmd, char *const *argv)
 		ALLOC_ARRAY(argv2, argc + 1);
 		argv2[0] = (char *)cmd;	/* full path to the script file */
 		memcpy(&argv2[1], &argv[1], sizeof(*argv) * argc);
+		exec_id = trace2_exec(prog, argv2);
 		pid = mingw_spawnv(prog, argv2, interpr);
 		if (pid >= 0) {
 			int status;
 			if (waitpid(pid, &status, 0) < 0)
 				status = 255;
+			trace2_exec_result(exec_id, status);
 			exit(status);
 		}
+		trace2_exec_result(exec_id, -1);
 		pid = 1;	/* indicate that we tried but failed */
 		free(prog);
 		free(argv2);
@@ -1973,12 +1977,17 @@ int mingw_execv(const char *cmd, char *const *argv)
 	/* check if git_command is a shell script */
 	if (!try_shell_exec(cmd, argv)) {
 		int pid, status;
+		int exec_id;
 
+		exec_id = trace2_exec(cmd, (const char **)argv);
 		pid = mingw_spawnv(cmd, (const char **)argv, NULL);
-		if (pid < 0)
+		if (pid < 0) {
+			trace2_exec_result(exec_id, -1);
 			return -1;
+		}
 		if (waitpid(pid, &status, 0) < 0)
 			status = 255;
+		trace2_exec_result(exec_id, status);
 		exit(status);
 	}
 	return -1;
diff --git a/compat/mingw.h b/compat/mingw.h
index ea46b647f18835..e391497e8d10c4 100644
--- a/compat/mingw.h
+++ b/compat/mingw.h
@@ -165,8 +165,7 @@ static inline int fcntl(int fd, int cmd, ...)
 	errno = EINVAL;
 	return -1;
 }
-/* bash cannot reliably detect negative return codes as failure */
-#define exit(code) exit((code) & 0xff)
+
 #define sigemptyset(x) (void)0
 static inline int sigaddset(sigset_t *set, int signum)
 { return 0; }
diff --git a/config.c b/config.c
index 5b39c3ef51131b..95d3613702cf9b 100644
--- a/config.c
+++ b/config.c
@@ -2709,6 +2709,8 @@ int git_config_set_gently(const char *key, const char *value)
 void git_config_set(const char *key, const char *value)
 {
 	git_config_set_multivar(key, value, NULL, 0);
+
+	trace2_cmd_set_config(key, value);
 }
 
 /*
diff --git a/exec-cmd.c b/exec-cmd.c
index 4f81f443105f07..7deeab30397cf2 100644
--- a/exec-cmd.c
+++ b/exec-cmd.c
@@ -209,6 +209,8 @@ static int git_get_exec_path(struct strbuf *buf, const char *argv0)
 		return -1;
 	}
 
+	trace2_cmd_path(buf->buf);
+
 	return 0;
 }
 
diff --git a/git-compat-util.h b/git-compat-util.h
index e6be418b4ee2f2..e7aa57730911e7 100644
--- a/git-compat-util.h
+++ b/git-compat-util.h
@@ -1291,6 +1291,13 @@ struct fscache;
 
 extern int cmd_main(int, const char **);
 
+/*
+ * Intercept all calls to exit() and route them to trace2 to
+ * optionally emit a message before calling the real exit().
+ */
+int trace2_cmd_exit_fl(const char *file, int line, int code);
+#define exit(code) exit(trace2_cmd_exit_fl(__FILE__, __LINE__, (code)))
+
 /*
  * You can mark a stack variable with UNLEAK(var) to avoid it being
  * reported as a leak by tools like LSAN or valgrind. The argument
diff --git a/git.c b/git.c
index a46643848a070c..fff26d3d9e9019 100644
--- a/git.c
+++ b/git.c
@@ -149,16 +149,20 @@ static int handle_options(const char ***argv, int *argc, int *envchanged)
 				git_set_exec_path(cmd + 1);
 			else {
 				puts(git_exec_path());
+				trace2_cmd_verb("_query_");
 				exit(0);
 			}
 		} else if (!strcmp(cmd, "--html-path")) {
 			puts(system_path(GIT_HTML_PATH));
+			trace2_cmd_verb("_query_");
 			exit(0);
 		} else if (!strcmp(cmd, "--man-path")) {
 			puts(system_path(GIT_MAN_PATH));
+			trace2_cmd_verb("_query_");
 			exit(0);
 		} else if (!strcmp(cmd, "--info-path")) {
 			puts(system_path(GIT_INFO_PATH));
+			trace2_cmd_verb("_query_");
 			exit(0);
 		} else if (!strcmp(cmd, "-p") || !strcmp(cmd, "--paginate")) {
 			use_pager = 1;
@@ -287,6 +291,7 @@ static int handle_options(const char ***argv, int *argc, int *envchanged)
 			(*argv)++;
 			(*argc)--;
 		} else if (skip_prefix(cmd, "--list-cmds=", &cmd)) {
+			trace2_cmd_verb("_query_");
 			if (!strcmp(cmd, "parseopt")) {
 				struct string_list list = STRING_LIST_INIT_DUP;
 				int i;
@@ -334,9 +339,14 @@ static int handle_alias(int *argcp, const char ***argv)
 			commit_pager_choice();
 
 			child.use_shell = 1;
+			child.trace2_child_class = "shell_alias";
 			argv_array_push(&child.args, alias_string + 1);
 			argv_array_pushv(&child.args, (*argv) + 1);
 
+			trace2_cmd_alias(alias_command, child.args.argv);
+			trace2_cmd_list_config();
+			trace2_cmd_verb("_run_shell_alias_");
+
 			ret = run_command(&child);
 			if (ret >= 0)   /* normal exit */
 				exit(ret);
@@ -371,6 +381,9 @@ static int handle_alias(int *argcp, const char ***argv)
 		/* insert after command name */
 		memcpy(new_argv + count, *argv + 1, sizeof(char *) * *argcp);
 
+		trace2_cmd_alias(alias_command, new_argv);
+		trace2_cmd_list_config();
+
 		*argv = new_argv;
 		*argcp += count - 1;
 
@@ -483,6 +496,8 @@ static int run_builtin(struct cmd_struct *p, int argc, const char **argv)
 		die("pre-command hook aborted command");
 
 	trace_argv_printf(argv, "trace: built-in: git");
+	trace2_cmd_verb(p->cmd);
+	trace2_cmd_list_config();
 
 	validate_cache_entries(&the_index);
 	exit_code = status = p->fn(argc, argv, prefix);
@@ -740,10 +755,15 @@ static void execv_dashed_external(const char **argv)
 	cmd.clean_on_exit = 1;
 	cmd.wait_after_clean = 1;
 	cmd.silent_exec_failure = 1;
+	cmd.trace2_child_class = "dashed";
 
 	if (run_pre_command_hook(cmd.args.argv))
 		die("pre-command hook aborted command");
 
+	/*
+	 * The code in run_command() logs trace2 child_start/child_exit
+	 * events, so we do not need to report exec/exec_result events here.
+	 */
 	trace_argv_printf(cmd.args.argv, "trace: exec:");
 
 	/*
@@ -753,10 +773,20 @@ static void execv_dashed_external(const char **argv)
 	 * the program.
 	 */
 	exit_code = status = run_command(&cmd);
-	if (status >= 0)
+
+	/*
+	 * If the child process ran and we are now going to exit, emit a
+	 * generic string as our trace2 command verb to indicate that we
+	 * launched a dashed command.
+	 */
+	if (status >= 0) {
+		trace2_cmd_verb("_run_dashed_");
 		exit(status);
-	else if (errno != ENOENT)
+	}
+	else if (errno != ENOENT) {
+		trace2_cmd_verb("_run_dashed_");
 		exit(128);
+	}
 
 	run_post_command_hook();
 }
@@ -783,6 +813,15 @@ static int run_argv(int *argcp, const char ***argv)
 			struct argv_array args = ARGV_ARRAY_INIT;
 			int i;
 
+			/*
+			 * The current process is committed to launching a
+			 * child process to run the command named in (**argv)
+			 * and exiting.  Log a generic string as the trace2
+			 * command verb to indicate this.  Note that the child
+			 * process will log the actual verb when it runs.
+			 */
+			trace2_cmd_verb("_run_git_alias_");
+
 			if (get_super_prefix())
 				die("%s doesn't support --super-prefix", **argv);
 
@@ -798,8 +837,8 @@ static int run_argv(int *argcp, const char ***argv)
 			 * if we fail because the command is not found, it is
 			 * OK to return. Otherwise, we just pass along the status code.
 			 */
-			i = run_command_v_opt(args.argv, RUN_SILENT_EXEC_FAILURE |
-					      RUN_CLEAN_ON_EXIT);
+			i = run_command_v_opt_tr2(args.argv, RUN_SILENT_EXEC_FAILURE |
+						  RUN_CLEAN_ON_EXIT, "git_alias");
 			if (i >= 0 || errno != ENOENT)
 				exit(i);
 			die("could not execute builtin %s", **argv);
diff --git a/remote-curl.c b/remote-curl.c
index 1220dffcdc57a1..8950b5c383f1b2 100644
--- a/remote-curl.c
+++ b/remote-curl.c
@@ -1340,6 +1340,13 @@ int cmd_main(int argc, const char **argv)
 	string_list_init(&options.deepen_not, 1);
 	string_list_init(&options.push_options, 1);
 
+	/*
+	 * Just report "remote-curl" here (folding all the various aliases
+	 * ("git-remote-http", "git-remote-https", and etc.) here since they
+	 * are all just copies of the same actual executable.
+	 */
+	trace2_cmd_verb("remote-curl");
+
 	remote = remote_get(argv[1]);
 
 	if (argc > 2) {
diff --git a/repository.c b/repository.c
index 5dd148671811b3..a84055ed1d9e3d 100644
--- a/repository.c
+++ b/repository.c
@@ -113,6 +113,8 @@ static int repo_init_gitdir(struct repository *repo, const char *gitdir)
 void repo_set_worktree(struct repository *repo, const char *path)
 {
 	repo->worktree = real_pathdup(path, 1);
+
+	trace2_def_repo(repo);
 }
 
 static int read_and_verify_repository_format(struct repository_format *format,
diff --git a/repository.h b/repository.h
index 9f16c42c1ed04a..97b03846ba544a 100644
--- a/repository.h
+++ b/repository.h
@@ -90,6 +90,9 @@ struct repository {
 	/* Repository's current hash algorithm, as serialized on disk. */
 	const struct git_hash_algo *hash_algo;
 
+	/* A unique-id for tracing purposes. */
+	int trace2_repo_id;
+
 	/* Configurations */
 
 	/* Indicate if a repository has a different 'commondir' from 'gitdir' */
diff --git a/run-command.c b/run-command.c
index f8a7f733718378..6977dde2d6d7dc 100644
--- a/run-command.c
+++ b/run-command.c
@@ -220,9 +220,29 @@ static int exists_in_PATH(const char *file)
 
 int sane_execvp(const char *file, char * const argv[])
 {
+#ifndef GIT_WINDOWS_NATIVE
+	/*
+	 * execvp() doesn't return, so we all we can do is tell trace2
+	 * what we are about to do and let it leave a hint in the log
+	 * (unless of course the execvp() fails).
+	 *
+	 * we skip this for Windows because the compat layer already
+	 * has to emulate the execvp() call anyway.
+	 */
+	int exec_id = trace2_exec(file, (const char**)argv);
+#endif
+
 	if (!execvp(file, argv))
 		return 0; /* cannot happen ;-) */
 
+#ifndef GIT_WINDOWS_NATIVE
+	{
+		int ec = errno;
+		trace2_exec_result(exec_id, ec);
+		errno = ec;
+	}
+#endif
+
 	/*
 	 * When a command can't be found because one of the directories
 	 * listed in $PATH is unsearchable, execvp reports EACCES, but
@@ -713,6 +733,7 @@ int start_command(struct child_process *cmd)
 		cmd->err = fderr[0];
 	}
 
+	trace2_child_start(cmd);
 	trace_run_command(cmd);
 
 	fflush(NULL);
@@ -927,6 +948,8 @@ int start_command(struct child_process *cmd)
 #endif
 
 	if (cmd->pid < 0) {
+		trace2_child_exit(cmd, -1);
+
 		if (need_in)
 			close_pair(fdin);
 		else if (cmd->in)
@@ -965,13 +988,16 @@ int start_command(struct child_process *cmd)
 int finish_command(struct child_process *cmd)
 {
 	int ret = wait_or_whine(cmd->pid, cmd->argv[0], 0);
+	trace2_child_exit(cmd, ret);
 	child_process_clear(cmd);
 	return ret;
 }
 
 int finish_command_in_signal(struct child_process *cmd)
 {
-	return wait_or_whine(cmd->pid, cmd->argv[0], 1);
+	int ret = wait_or_whine(cmd->pid, cmd->argv[0], 1);
+	trace2_child_exit(cmd, ret);
+	return ret;
 }
 
 
@@ -993,7 +1019,18 @@ int run_command_v_opt(const char **argv, int opt)
 	return run_command_v_opt_cd_env(argv, opt, NULL, NULL);
 }
 
+int run_command_v_opt_tr2(const char **argv, int opt, const char *tr2_class)
+{
+	return run_command_v_opt_cd_env_tr2(argv, opt, NULL, NULL, tr2_class);
+}
+
 int run_command_v_opt_cd_env(const char **argv, int opt, const char *dir, const char *const *env)
+{
+	return run_command_v_opt_cd_env_tr2(argv, opt, dir, env, NULL);
+}
+
+int run_command_v_opt_cd_env_tr2(const char **argv, int opt, const char *dir, const char *const *env,
+				 const char *tr2_class)
 {
 	struct child_process cmd = CHILD_PROCESS_INIT;
 	cmd.argv = argv;
@@ -1005,6 +1042,7 @@ int run_command_v_opt_cd_env(const char **argv, int opt, const char *dir, const
 	cmd.clean_on_exit = opt & RUN_CLEAN_ON_EXIT ? 1 : 0;
 	cmd.dir = dir;
 	cmd.env = env;
+	cmd.trace2_child_class = tr2_class;
 	return run_command(&cmd);
 }
 
@@ -1377,6 +1415,7 @@ int run_hook_argv(const char *const *env, const char *name,
 	hook.env = env;
 	hook.no_stdin = 1;
 	hook.stdout_to_stderr = 1;
+	hook.trace2_hook_name = name;
 
 	return run_command(&hook);
 }
@@ -1848,6 +1887,15 @@ int run_processes_parallel(int n,
 	int output_timeout = 100;
 	int spawn_cap = 4;
 	struct parallel_processes pp;
+	/*
+	 * TODO Currently all callers of run_processes_parallel()
+	 * are in the submodule code, so hard-coding the category
+	 * is OK for now.  Later, pass in category to this function.
+	 */
+	const char *category = "submodule";
+
+	trace2_region_enter_printf(category, "run_pp", NULL,
+				   "max:%d", ((n < 1) ? online_cpus() : n));
 
 	pp_init(&pp, n, get_next_task, start_failure, task_finished, pp_cb);
 	while (1) {
@@ -1877,5 +1925,8 @@ int run_processes_parallel(int n,
 	}
 
 	pp_cleanup(&pp);
+
+	trace2_region_leave(category, "run_pp", NULL);
+
 	return 0;
 }
diff --git a/run-command.h b/run-command.h
index b17abb44a43722..5ad1357ae5d6a3 100644
--- a/run-command.h
+++ b/run-command.h
@@ -10,6 +10,12 @@ struct child_process {
 	struct argv_array args;
 	struct argv_array env_array;
 	pid_t pid;
+
+	int trace2_child_id;
+	uint64_t trace2_child_us_start;
+	const char *trace2_child_class;
+	const char *trace2_hook_name;
+
 	/*
 	 * Using .in, .out, .err:
 	 * - Specify 0 for no redirections (child inherits stdin, stdout,
@@ -75,12 +81,15 @@ extern int run_hook_argv(const char *const *env, const char *name,
 #define RUN_USING_SHELL 16
 #define RUN_CLEAN_ON_EXIT 32
 int run_command_v_opt(const char **argv, int opt);
-
+int run_command_v_opt_tr2(const char **argv, int opt, const char *tr2_class
+);
 /*
  * env (the environment) is to be formatted like environ: "VAR=VALUE".
  * To unset an environment variable use just "VAR".
  */
 int run_command_v_opt_cd_env(const char **argv, int opt, const char *dir, const char *const *env);
+int run_command_v_opt_cd_env_tr2(const char **argv, int opt, const char *dir, const char *const *env,
+				 const char *tr2_class);
 
 /**
  * Execute the given command, sending "in" to its stdin, and capturing its
diff --git a/sh-i18n--envsubst.c b/sh-i18n--envsubst.c
index 09c6b445b96312..2296ba1a2d6361 100644
--- a/sh-i18n--envsubst.c
+++ b/sh-i18n--envsubst.c
@@ -14,6 +14,7 @@
  */
 
 #include "git-compat-util.h"
+#include "trace2.h"
 
 /* Substitution of environment variables in shell format strings.
    Copyright (C) 2003-2007 Free Software Foundation, Inc.
@@ -67,6 +68,8 @@ cmd_main (int argc, const char *argv[])
   /* Default values for command line options.  */
   /* unsigned short int show_variables = 0; */
 
+  trace2_cmd_verb("sh-i18n--envsubst");
+
   switch (argc)
 	{
 	case 1:
diff --git a/t/helper/test-parse-options.c b/t/helper/test-parse-options.c
index 47fee660b86a6e..5318681739d9c6 100644
--- a/t/helper/test-parse-options.c
+++ b/t/helper/test-parse-options.c
@@ -2,6 +2,7 @@
 #include "cache.h"
 #include "parse-options.h"
 #include "string-list.h"
+#include "trace2.h"
 
 static int boolean = 0;
 static int integer = 0;
@@ -153,6 +154,8 @@ int cmd__parse_options(int argc, const char **argv)
 	int i;
 	int ret = 0;
 
+	trace2_cmd_verb("_parse_");
+
 	argc = parse_options(argc, (const char **)argv, prefix, options, usage, 0);
 
 	if (length_cb.called) {
diff --git a/t/helper/test-tool.c b/t/helper/test-tool.c
index 52304d0748ce52..cfb46a720ea919 100644
--- a/t/helper/test-tool.c
+++ b/t/helper/test-tool.c
@@ -1,5 +1,6 @@
 #include "git-compat-util.h"
 #include "test-tool.h"
+#include "trace2.h"
 
 struct test_cmd {
 	const char *name;
@@ -80,6 +81,8 @@ int cmd_main(int argc, const char **argv)
 		if (!strcmp(cmds[i].name, argv[1])) {
 			argv++;
 			argc--;
+			trace2_cmd_verb(cmds[i].name);
+			trace2_cmd_list_config();
 			return cmds[i].fn(argc, argv);
 		}
 	}
diff --git a/t/t0001-init.sh b/t/t0001-init.sh
index a6c5fe9e1475ae..d13aa011e00431 100755
--- a/t/t0001-init.sh
+++ b/t/t0001-init.sh
@@ -93,6 +93,7 @@ test_expect_success 'No extra GIT_* on alias scripts' '
 		sed -n \
 			-e "/^GIT_PREFIX=/d" \
 			-e "/^GIT_TEXTDOMAINDIR=/d" \
+			-e "/^GIT_TR2_PARENT/d" \
 			-e "/^GIT_/s/=.*//p" |
 		sort
 	EOF
diff --git a/trace2.c b/trace2.c
new file mode 100644
index 00000000000000..66c0fcfd23fc86
--- /dev/null
+++ b/trace2.c
@@ -0,0 +1,817 @@
+#include "cache.h"
+#include "config.h"
+#include "json-writer.h"
+#include "quote.h"
+#include "run-command.h"
+#include "sigchain.h"
+#include "thread-utils.h"
+#include "version.h"
+#include "trace2/tr2_cfg.h"
+#include "trace2/tr2_dst.h"
+#include "trace2/tr2_sid.h"
+#include "trace2/tr2_tgt.h"
+#include "trace2/tr2_tls.h"
+#include "trace2/tr2_verb.h"
+
+static int trace2_enabled;
+
+static int tr2_next_child_id; /* modify under lock */
+static int tr2_next_exec_id; /* modify under lock */
+static int tr2_next_repo_id = 1; /* modify under lock. zero is reserved */
+
+/*
+ * A table of the builtin TRACE2 targets.  Each of these may be independently
+ * enabled or disabled.  Each TRACE2 API will try to write an event to *each*
+ * of the enabled targets.
+ */
+static struct tr2_tgt *tr2_tgt_builtins[] =
+{
+	&tr2_tgt_normal,
+	&tr2_tgt_perf,
+	&tr2_tgt_event,
+	NULL
+};
+
+#define for_each_builtin(j, tgt_j)			\
+	for (j = 0, tgt_j = tr2_tgt_builtins[j];	\
+	     tgt_j;					\
+	     j++, tgt_j = tr2_tgt_builtins[j])
+
+#define for_each_wanted_builtin(j, tgt_j)	\
+	for_each_builtin(j, tgt_j)		\
+	if (tr2_dst_trace_want(tgt_j->pdst))
+
+/*
+ * Force (rather than lazily) initialize any of the requested
+ * builtin TRACE2 targets at startup (and before we've seen an
+ * actual TRACE2 event call) so we can see if we need to setup
+ * the TR2 and TLS machinery.
+ *
+ * Return the number of builtin targets enabled.
+ */
+static int tr2_tgt_want_builtins(void)
+{
+	struct tr2_tgt *tgt_j;
+	int j;
+	int sum = 0;
+
+	for_each_builtin(j, tgt_j) {
+		if (tgt_j->pfn_init())
+			sum++;
+	}
+
+	return sum;
+}
+
+/*
+ * Properly terminate each builtin target.  Give each target
+ * a chance to write a summary event and/or flush if necessary
+ * and then close the fd.
+ */
+static void tr2_tgt_disable_builtins(void)
+{
+	struct tr2_tgt *tgt_j;
+	int j;
+
+	for_each_builtin(j, tgt_j) {
+		tgt_j->pfn_term();
+	}
+}
+
+/*****************************************************************
+ * TODO remove this section header
+ *****************************************************************/
+
+static int tr2main_exit_code;
+
+/*
+ * Our atexit routine should run after everything has finished.
+ *
+ * Note that events generated here might not actually appear if
+ * we are writing to fd 1 or 2 and our atexit routine runs after
+ * the pager's atexit routine (since it closes them to shutdown
+ * the pipes).
+ */
+static void tr2main_atexit_handler(void)
+{
+	struct tr2_tgt *tgt_j;
+	int j;
+	uint64_t us_now;
+	uint64_t us_elapsed_absolute;
+
+	us_now = getnanotime() / 1000;
+	us_elapsed_absolute = tr2tls_absolute_elapsed(us_now);
+
+	/*
+	 * Clear any unbalanced regions so that our atexit message
+	 * does not appear nested.  This improves the appearance of
+	 * the trace output if someone calls die(), for example.
+	 */
+	tr2tls_pop_unwind_self();
+	
+	for_each_wanted_builtin(j, tgt_j) {
+		if (tgt_j->pfn_atexit)
+			tgt_j->pfn_atexit(us_elapsed_absolute,
+					  tr2main_exit_code);
+	}
+
+	tr2_tgt_disable_builtins();
+
+	tr2tls_release();
+	tr2_sid_release();
+	tr2_verb_release();
+	tr2_cfg_free_patterns();
+
+	trace2_enabled = 0;
+}
+
+static void tr2main_signal_handler(int signo)
+{
+	struct tr2_tgt *tgt_j;
+	int j;
+	uint64_t us_now;
+	uint64_t us_elapsed_absolute;
+
+	us_now = getnanotime() / 1000;
+	us_elapsed_absolute = tr2tls_absolute_elapsed(us_now);
+
+	for_each_wanted_builtin(j, tgt_j) {
+		if (tgt_j->pfn_signal)
+			tgt_j->pfn_signal(us_elapsed_absolute, signo);
+	}
+
+	sigchain_pop(signo);
+	raise(signo);
+}
+
+/*****************************************************************
+ * TODO remove this section header
+ *****************************************************************/
+
+void trace2_initialize_fl(const char *file, int line)
+{
+	struct tr2_tgt *tgt_j;
+	int j;
+
+	if (trace2_enabled)
+		return;
+
+	if (!tr2_tgt_want_builtins())
+		return;
+	trace2_enabled = 1;
+
+	tr2_sid_get();
+
+	atexit(tr2main_atexit_handler);
+	sigchain_push(SIGPIPE, tr2main_signal_handler);
+	tr2tls_init();
+
+	/*
+	 * Emit 'version' message on each active builtin target.
+	 */
+	for_each_wanted_builtin(j, tgt_j) {
+		if (tgt_j->pfn_version_fl)
+			tgt_j->pfn_version_fl(file, line);
+	}
+}
+
+int trace2_is_enabled(void)
+{
+	return trace2_enabled;
+}
+
+void trace2_cmd_start_fl(const char *file, int line, const char **argv)
+{
+	struct tr2_tgt *tgt_j;
+	int j;
+
+	if (!trace2_enabled)
+		return;
+
+	for_each_wanted_builtin(j, tgt_j) {
+		if (tgt_j->pfn_start_fl)
+			tgt_j->pfn_start_fl(file, line, argv);
+	}
+}
+
+int trace2_cmd_exit_fl(const char *file, int line, int code)
+{
+	struct tr2_tgt *tgt_j;
+	int j;
+	uint64_t us_now;
+	uint64_t us_elapsed_absolute;
+
+	code &= 0xff;
+
+	if (!trace2_enabled)
+		return code;
+
+	tr2main_exit_code = code;
+
+	us_now = getnanotime() / 1000;
+	us_elapsed_absolute = tr2tls_absolute_elapsed(us_now);
+
+	for_each_wanted_builtin(j, tgt_j) {
+		if (tgt_j->pfn_exit_fl)
+			tgt_j->pfn_exit_fl(file, line, us_elapsed_absolute, code);
+	}
+
+	return code;
+}
+
+void trace2_cmd_error_va_fl(const char *file, int line,
+			    const char *fmt, va_list ap)
+{
+	struct tr2_tgt *tgt_j;
+	int j;
+
+	if (!trace2_enabled)
+		return;
+
+	/*
+	 * We expect each target function to treat 'ap' as constant
+	 * and use va_copy (because an 'ap' can only be walked once).
+	 */
+	for_each_wanted_builtin(j, tgt_j) {
+		if (tgt_j->pfn_error_va_fl)
+			tgt_j->pfn_error_va_fl(file, line, fmt, ap);
+	}
+}
+
+void trace2_cmd_path_fl(const char *file, int line, const char *pathname)
+{
+	struct tr2_tgt *tgt_j;
+	int j;
+
+	if (!trace2_enabled)
+		return;
+
+	for_each_wanted_builtin(j, tgt_j) {
+		if (tgt_j->pfn_command_path_fl)
+			tgt_j->pfn_command_path_fl(file, line, pathname);
+	}
+}
+
+void trace2_cmd_verb_fl(const char *file, int line, const char *command_verb)
+{
+	struct tr2_tgt *tgt_j;
+	const char *hierarchy;
+	int j;
+
+	if (!trace2_enabled)
+		return;
+
+	tr2_verb_append_hierarchy(command_verb);
+	hierarchy = tr2_verb_get_hierarchy();
+
+	for_each_wanted_builtin(j, tgt_j) {
+		if (tgt_j->pfn_command_verb_fl)
+			tgt_j->pfn_command_verb_fl(file, line, command_verb,
+						   hierarchy);
+	}
+}
+
+void trace2_cmd_subverb_fl(const char *file, int line,
+			   const char *command_subverb)
+{
+	struct tr2_tgt *tgt_j;
+	int j;
+
+	if (!trace2_enabled)
+		return;
+
+	for_each_wanted_builtin(j, tgt_j) {
+		if (tgt_j->pfn_command_subverb_fl)
+			tgt_j->pfn_command_subverb_fl(file, line,
+						      command_subverb);
+	}
+}
+
+void trace2_cmd_alias_fl(const char *file, int line,
+			 const char *alias, const char **argv)
+{
+	struct tr2_tgt *tgt_j;
+	int j;
+
+	if (!trace2_enabled)
+		return;
+
+	for_each_wanted_builtin(j, tgt_j) {
+		if (tgt_j->pfn_alias_fl)
+			tgt_j->pfn_alias_fl(file, line, alias, argv);
+	}
+}
+
+void trace2_cmd_list_config_fl(const char *file, int line)
+{
+	if (!trace2_enabled)
+		return;
+
+	tr2_cfg_list_config_fl(file, line);
+}
+
+void trace2_cmd_set_config_fl(const char *file, int line,
+			      const char *key, const char *value)
+{
+	if (!trace2_enabled)
+		return;
+
+	tr2_cfg_set_fl(file, line, key, value);
+}
+
+void trace2_child_start_fl(const char *file, int line,
+			   struct child_process *cmd)
+{
+	struct tr2_tgt *tgt_j;
+	int j;
+	uint64_t us_now;
+	uint64_t us_elapsed_absolute;
+
+	if (!trace2_enabled)
+		return;
+
+	us_now = getnanotime() / 1000;
+	us_elapsed_absolute = tr2tls_absolute_elapsed(us_now);
+
+	cmd->trace2_child_id = tr2tls_locked_increment(&tr2_next_child_id);
+	cmd->trace2_child_us_start = us_now;
+
+	for_each_wanted_builtin(j, tgt_j) {
+		if (tgt_j->pfn_child_start_fl)
+			tgt_j->pfn_child_start_fl(file, line,
+						  us_elapsed_absolute, cmd);
+	}
+}
+
+void trace2_child_exit_fl(const char *file, int line,
+			  struct child_process *cmd,
+			  int child_exit_code)
+{
+	struct tr2_tgt *tgt_j;
+	int j;
+	uint64_t us_now;
+	uint64_t us_elapsed_absolute;
+	uint64_t us_elapsed_child;
+
+	if (!trace2_enabled)
+		return;
+
+	us_now = getnanotime() / 1000;
+	us_elapsed_absolute = tr2tls_absolute_elapsed(us_now);
+	
+	if (cmd->trace2_child_us_start)
+		us_elapsed_child = us_now - cmd->trace2_child_us_start;
+	else
+		us_elapsed_child = 0;
+	
+	for_each_wanted_builtin(j, tgt_j) {
+		if (tgt_j->pfn_child_exit_fl)
+			tgt_j->pfn_child_exit_fl(
+				file, line, us_elapsed_absolute,
+				cmd->trace2_child_id,
+				cmd->pid,
+				child_exit_code, us_elapsed_child);
+	}
+}
+
+int trace2_exec_fl(const char *file, int line,
+		   const char *exe, const char **argv)
+{
+	struct tr2_tgt *tgt_j;
+	int j;
+	int exec_id;
+	uint64_t us_now;
+	uint64_t us_elapsed_absolute;
+
+	if (!trace2_enabled)
+		return -1;
+
+	us_now = getnanotime() / 1000;
+	us_elapsed_absolute = tr2tls_absolute_elapsed(us_now);
+
+	exec_id = tr2tls_locked_increment(&tr2_next_exec_id);
+
+	for_each_wanted_builtin(j, tgt_j) {
+		if (tgt_j->pfn_exec_fl)
+			tgt_j->pfn_exec_fl(file, line, us_elapsed_absolute,
+					   exec_id, exe, argv);
+	}
+
+	return exec_id;
+}
+
+void trace2_exec_result_fl(const char *file, int line, int exec_id, int code)
+{
+	struct tr2_tgt *tgt_j;
+	int j;
+	uint64_t us_now;
+	uint64_t us_elapsed_absolute;
+
+	if (!trace2_enabled)
+		return;
+
+	us_now = getnanotime() / 1000;
+	us_elapsed_absolute = tr2tls_absolute_elapsed(us_now);
+
+	for_each_wanted_builtin(j, tgt_j) {
+		if (tgt_j->pfn_exec_result_fl)
+			tgt_j->pfn_exec_result_fl(file, line,
+						  us_elapsed_absolute,
+						  exec_id, code);
+	}
+}
+
+void trace2_thread_start_fl(const char *file, int line,
+			    const char *thread_name)
+{
+	struct tr2_tgt *tgt_j;
+	int j;
+	uint64_t us_now;
+	uint64_t us_elapsed_absolute;
+
+	if (!trace2_enabled)
+		return;
+
+	if (tr2tls_is_main_thread())
+	{
+		/*
+		 * We should only be called from the new thread's thread-proc,
+		 * so this is technically a bug.  But in those cases where the
+		 * main thread also runs the thread-proc function (or when we
+		 * are built with threading disabled), we need to allow it.
+		 *
+		 * Convert this call to a region-enter so the nesting looks
+		 * looks correct.  
+		 */
+		trace2_region_enter_printf_fl(file, line, NULL, NULL, NULL,
+					      "thread-proc on main: %s",
+					      thread_name);
+		return;
+	}
+
+	us_now = getnanotime() / 1000;
+	us_elapsed_absolute = tr2tls_absolute_elapsed(us_now);
+
+	tr2tls_create_self(thread_name);
+
+	for_each_wanted_builtin(j, tgt_j) {
+		if (tgt_j->pfn_thread_start_fl)
+			tgt_j->pfn_thread_start_fl(file, line,
+						   us_elapsed_absolute);
+	}
+}
+
+void trace2_thread_exit_fl(const char *file, int line)
+{
+	struct tr2_tgt *tgt_j;
+	int j;
+	uint64_t us_now;
+	uint64_t us_elapsed_absolute;
+	uint64_t us_elapsed_thread;
+
+	if (!trace2_enabled)
+		return;
+
+	if (tr2tls_is_main_thread())
+	{
+		/*
+		 * We should only be called from the exiting thread's thread-proc,
+		 * so this is technically a bug.  But in those cases where the
+		 * main thread also runs the thread-proc function (or when we
+		 * are built with threading disabled), we need to allow it.
+		 *
+		 * Convert this call to a region-leave so the nesting looks
+		 * looks correct.  
+		 */
+		trace2_region_leave_printf_fl(file, line, NULL, NULL, NULL,
+					      "thread-proc on main");
+		return;
+	}
+
+	us_now = getnanotime() / 1000;
+	us_elapsed_absolute = tr2tls_absolute_elapsed(us_now);
+
+	/*
+	 * Clear any unbalanced regions and then get the relative time
+	 * for the outer-most region (which we pushed when the thread
+	 * started).  This gives us the run time of the thread.
+	 */
+	tr2tls_pop_unwind_self();
+	us_elapsed_thread = tr2tls_region_elasped_self(us_now);
+
+	for_each_wanted_builtin(j, tgt_j) {
+		if (tgt_j->pfn_thread_exit_fl)
+			tgt_j->pfn_thread_exit_fl(file, line,
+						  us_elapsed_absolute,
+						  us_elapsed_thread);
+	}
+
+	tr2tls_unset_self();
+}
+
+void trace2_def_param_fl(const char *file, int line,
+			 const char *param, const char *value)
+{
+	struct tr2_tgt *tgt_j;
+	int j;
+
+	if (!trace2_enabled)
+		return;
+
+	for_each_wanted_builtin(j, tgt_j) {
+		if (tgt_j->pfn_param_fl)
+			tgt_j->pfn_param_fl(file, line, param, value);
+	}
+}
+
+void trace2_def_repo_fl(const char *file, int line,
+			struct repository *repo)
+{
+	struct tr2_tgt *tgt_j;
+	int j;
+
+	if (!trace2_enabled)
+		return;
+
+	if (repo->trace2_repo_id)
+		return;
+
+	repo->trace2_repo_id = tr2tls_locked_increment(&tr2_next_repo_id);
+
+	for_each_wanted_builtin(j, tgt_j) {
+		if (tgt_j->pfn_repo_fl)
+			tgt_j->pfn_repo_fl(file, line, repo);
+	}
+}
+
+void trace2_region_enter_printf_va_fl(const char *file, int line,
+				      const char *category,
+				      const char *label,
+				      const struct repository *repo,
+				      const char *fmt, va_list ap)
+{
+	struct tr2_tgt *tgt_j;
+	int j;
+	uint64_t us_now;
+	uint64_t us_elapsed_absolute;
+
+	if (!trace2_enabled)
+		return;
+
+	us_now = getnanotime() / 1000;
+	us_elapsed_absolute = tr2tls_absolute_elapsed(us_now);
+
+	/*
+	 * Print the region-enter message at the current nesting
+	 * (indentation) level and then push a new level.
+	 *
+	 * We expect each target function to treat 'ap' as constant
+	 * and use va_copy.
+	 */
+	for_each_wanted_builtin(j, tgt_j) {
+		if (tgt_j->pfn_region_enter_printf_va_fl)
+			tgt_j->pfn_region_enter_printf_va_fl(
+				file, line, us_elapsed_absolute,
+				category, label, repo, fmt, ap);
+	}
+
+	tr2tls_push_self(us_now);
+}
+
+void trace2_region_enter_fl(const char *file, int line,
+			    const char *category,
+			    const char *label,
+			    const struct repository *repo)
+{
+	trace2_region_enter_printf_va_fl(file, line,
+					 category, label, repo,
+					 NULL, NULL);
+}
+
+void trace2_region_enter_printf_fl(const char *file, int line,
+				   const char *category,
+				   const char *label,
+				   const struct repository *repo,
+				   const char *fmt, ...)
+{
+	va_list ap;
+
+	va_start(ap, fmt);
+	trace2_region_enter_printf_va_fl(file, line,
+					 category, label, repo,
+					 fmt, ap);
+	va_end(ap);
+}
+
+#ifndef HAVE_VARIADIC_MACROS
+void trace2_region_enter_printf(const char *category, const char *label,
+				const struct repository *repo,
+				const char *fmt, ...)
+{
+	va_list ap;
+
+	va_start(ap, fmt);
+	trace2_region_enter_printf_va_fl(NULL, 0,
+					 category, label, repo,
+					 fmt, ap);
+	va_end(ap);
+}
+#endif
+
+void trace2_region_leave_printf_va_fl(const char *file, int line,
+				      const char *category,
+				      const char *label,
+				      const struct repository *repo,
+				      const char *fmt, va_list ap)
+{
+	struct tr2_tgt *tgt_j;
+	int j;
+	uint64_t us_now;
+	uint64_t us_elapsed_absolute;
+	uint64_t us_elapsed_region;
+
+	if (!trace2_enabled)
+		return;
+
+	us_now = getnanotime() / 1000;
+	us_elapsed_absolute = tr2tls_absolute_elapsed(us_now);
+
+	/*
+	 * Get the elapsed time in the current region before we
+	 * pop it off the stack.  Pop the stack.  And then print
+	 * the perf message at the new (shallower) level so that
+	 * it lines up with the corresponding push/enter.
+	 */
+	us_elapsed_region = tr2tls_region_elasped_self(us_now);
+	
+	tr2tls_pop_self();
+
+	/*
+	 * We expect each target function to treat 'ap' as constant
+	 * and use va_copy.
+	 */
+	for_each_wanted_builtin(j, tgt_j) {
+		if (tgt_j->pfn_region_leave_printf_va_fl)
+			tgt_j->pfn_region_leave_printf_va_fl(
+				file, line, us_elapsed_absolute,
+				us_elapsed_region,
+				category, label, repo,
+				fmt, ap);
+	}
+}
+
+void trace2_region_leave_fl(const char *file, int line,
+			    const char *category,
+			    const char *label,
+			    const struct repository *repo)
+{
+	trace2_region_leave_printf_va_fl(file, line,
+					 category, label, repo,
+					 NULL, NULL);
+}
+
+void trace2_region_leave_printf_fl(const char *file, int line,
+				   const char *category,
+				   const char *label,
+				   const struct repository *repo,
+				   const char *fmt, ...)
+{
+	va_list ap;
+
+	va_start(ap, fmt);
+	trace2_region_leave_printf_va_fl(file, line,
+					 category, label, repo,
+					 fmt, ap);
+	va_end(ap);
+}
+
+#ifndef HAVE_VARIADIC_MACROS
+void trace2_region_leave_printf(const char *category, const char *label,
+				const struct repository *repo,
+				const char *fmt, ...)
+{
+	va_list ap;
+
+	va_start(ap, fmt);
+	trace2_region_leave_printf_va_fl(NULL, 0,
+					 category, label, repo,
+					 fmt, ap);
+	va_end(ap);
+}
+#endif
+
+void trace2_data_string_fl(const char *file, int line,
+			   const char *category,
+			   const struct repository *repo,
+			   const char *key,
+			   const char *value)
+{
+	struct tr2_tgt *tgt_j;
+	int j;
+	uint64_t us_now;
+	uint64_t us_elapsed_absolute;
+	uint64_t us_elapsed_region;
+
+	if (!trace2_enabled)
+		return;
+
+	us_now = getnanotime() / 1000;
+	us_elapsed_absolute = tr2tls_absolute_elapsed(us_now);
+	us_elapsed_region = tr2tls_region_elasped_self(us_now);
+
+	for_each_wanted_builtin(j, tgt_j) {
+		if (tgt_j->pfn_data_fl)
+			tgt_j->pfn_data_fl(file, line, us_elapsed_absolute,
+					   us_elapsed_region,
+					   category, repo, key, value);
+	}
+}
+
+void trace2_data_intmax_fl(const char *file, int line,
+			   const char *category,
+			   const struct repository *repo,
+			   const char *key,
+			   intmax_t value)
+{
+	struct strbuf buf_string = STRBUF_INIT;
+
+	if (!trace2_enabled)
+		return;
+
+	strbuf_addf(&buf_string, "%"PRIdMAX, value);
+	trace2_data_string_fl(file, line, category, repo, key, buf_string.buf);
+	strbuf_release(&buf_string);
+}
+
+void trace2_data_json_fl(const char *file, int line,
+			 const char *category,
+			 const struct repository *repo,
+			 const char *key,
+			 const struct json_writer *value)
+{
+	struct tr2_tgt *tgt_j;
+	int j;
+	uint64_t us_now;
+	uint64_t us_elapsed_absolute;
+	uint64_t us_elapsed_region;
+
+	if (!trace2_enabled)
+		return;
+
+	us_now = getnanotime() / 1000;
+	us_elapsed_absolute = tr2tls_absolute_elapsed(us_now);
+	us_elapsed_region = tr2tls_region_elasped_self(us_now);
+
+	for_each_wanted_builtin(j, tgt_j) {
+		if (tgt_j->pfn_data_fl)
+			tgt_j->pfn_data_json_fl(file, line, us_elapsed_absolute,
+						us_elapsed_region,
+						category, repo, key, value);
+	}
+}
+
+void trace2_printf_va_fl(const char *file, int line,
+			 const char *fmt, va_list ap)
+{
+	struct tr2_tgt *tgt_j;
+	int j;
+	uint64_t us_now;
+	uint64_t us_elapsed_absolute;
+
+	if (!trace2_enabled)
+		return;
+
+	us_now = getnanotime() / 1000;
+	us_elapsed_absolute = tr2tls_absolute_elapsed(us_now);
+
+	/*
+	 * We expect each target function to treat 'ap' as constant
+	 * and use va_copy.
+	 */
+	for_each_wanted_builtin(j, tgt_j) {
+		if (tgt_j->pfn_printf_va_fl)
+			tgt_j->pfn_printf_va_fl(file, line, us_elapsed_absolute,
+						fmt, ap);
+	}
+}
+
+void trace2_printf_fl(const char *file, int line,
+		      const char *fmt, ...)
+{
+	va_list ap;
+
+	va_start(ap, fmt);
+	trace2_printf_va_fl(file, line, fmt, ap);
+	va_end(ap);
+}
+
+#ifndef HAVE_VARIADIC_MACROS
+void trace2_printf(const char *fmt, ...)
+{
+	va_list ap;
+
+	va_start(ap, fmt);
+	trace2_printf_va_fl(NULL, 0, fmt, ap);
+	va_end(ap);
+}
+#endif
diff --git a/trace2.h b/trace2.h
new file mode 100644
index 00000000000000..ce89d040b91a50
--- /dev/null
+++ b/trace2.h
@@ -0,0 +1,390 @@
+#ifndef TRACE2_H
+#define TRACE2_H
+
+struct child_process;
+struct repository;
+struct json_writer;
+
+/*
+ * The public TRACE2 routines are grouped into the following groups:
+ *
+ * [] trace2_initialize -- initialization.
+ * [] trace2_cmd_*      -- emit command/control messages.
+ * [] trace2_child*     -- emit child start/stop messages.
+ * [] trace2_exec*      -- emit exec start/stop messages.
+ * [] trace2_thread*    -- emit thread start/stop messages.
+ * [] trace2_def*       -- emit definition/parameter mesasges.
+ * [] trace2_region*    -- emit region nesting messages.
+ * [] trace2_data*      -- emit region/thread/repo data messages.
+ * [] trace2_printf*    -- legacy trace[1] messages.
+ */
+
+/*
+ * Initialize TRACE2 tracing facility if any of the builtin TRACE2
+ * targets are enabled in the environment.  Emits a 'version' event.
+ *
+ * Cleanup/Termination is handled automatically by a registered
+ * atexit() routine.
+ */
+void trace2_initialize_fl(const char *file, int line);
+
+#define trace2_initialize() trace2_initialize_fl(__FILE__, __LINE__)
+
+/*
+ * Return true if trace2 is enabled.
+ */
+int trace2_is_enabled(void);
+
+/*
+ * Emit a 'start' event with the original (unmodified) argv.
+ */
+void trace2_cmd_start_fl(const char *file, int line, const char **argv);
+
+#define trace2_cmd_start(argv) trace2_cmd_start_fl(__FILE__, __LINE__, (argv))
+
+/*
+ * Emit an 'exit' event.
+ *
+ * Write the exit-code that will be passed to exit() or returned
+ * from main().
+ *
+ * Use this prior to actually calling exit().
+ * See "#define exit()" in git-compat-util.h
+ */
+int trace2_cmd_exit_fl(const char *file, int line, int code);
+
+#define trace2_cmd_exit(code) (trace2_cmd_exit_fl(__FILE__, __LINE__, (code)))
+
+/*
+ * Emit an 'error' event.
+ *
+ * Write an error message to the TRACE2 targets.
+ */
+void trace2_cmd_error_va_fl(const char *file, int line,
+			    const char *fmt, va_list ap);
+
+#define trace2_cmd_error_va(fmt, ap) \
+	trace2_cmd_error_va_fl(__FILE__, __LINE__, (fmt), (ap))
+
+/*
+ * Emit a 'pathname' event with the canonical pathname of the current process
+ * This gives post-processors a simple field to identify the command without
+ * having to parse the argv.  For example, to distinguish invocations from
+ * installed versus debug executables.
+ */
+void trace2_cmd_path_fl(const char *file, int line, const char *pathname);
+
+#define trace2_cmd_path(p) \
+	trace2_cmd_path_fl(__FILE__, __LINE__, (p))
+
+/*
+ * Emit a 'cmd_verb' event with the canonical name of the (usually)
+ * builtin command.  This gives post-processors a simple field
+ * to identify the command verb without having to parse the argv.
+ */
+void trace2_cmd_verb_fl(const char *file, int line, const char *command_verb);
+
+#define trace2_cmd_verb(v) \
+	trace2_cmd_verb_fl(__FILE__, __LINE__, (v))
+
+/*
+ * Emit a 'cmd_subverb' event to further describe the command being run.
+ * For example, "checkout" can checkout a single file or can checkout a
+ * different branch.  This gives post-processors a simple field to compare
+ * equivalent commands without having to parse the argv.
+ */
+void trace2_cmd_subverb_fl(const char *file, int line,
+			   const char *command_subverb);
+
+#define trace2_cmd_subverb(sv) \
+	trace2_cmd_subverb_fl(__FILE__, __LINE__, (sv))
+
+/*
+ * Emit an 'alias' expansion event.
+ */
+void trace2_cmd_alias_fl(const char *file, int line,
+			 const char *alias, const char **argv);
+
+#define trace2_cmd_alias(alias, argv) \
+	trace2_cmd_alias_fl(__FILE__, __LINE__, (alias), (argv))
+
+/*
+ * Emit one or more 'def_param' events for "interesting" configuration
+ * settings.
+ *
+ * The environment variable "GIT_TR2_CONFIG_PARAMS" can be set to a
+ * list of patterns considered important.  For example:
+ *
+ *    GIT_TR2_CONFIG_PARAMS="core.*,remote.*.url"
+ *
+ * Note: this routine does a read-only iteration on the config data
+ * (using read_early_config()), so it must not be called until enough
+ * of the process environment has been established.  This includes the
+ * location of the git and worktree directories, expansion of any "-c"
+ * and "-C" command line options, and etc.
+ */
+void trace2_cmd_list_config_fl(const char *file, int line);
+
+#define trace2_cmd_list_config() \
+	trace2_cmd_list_config_fl(__FILE__, __LINE__)
+
+/*
+ * Emit a "def_param" event for the given config key/value pair IF
+ * we consider the key to be "interesting".
+ *
+ * Use this for new/updated config settings created/updated after
+ * trace2_cmd_list_config() is called.
+ */
+void trace2_cmd_set_config_fl(const char *file, int line,
+			      const char *key, const char *value);
+
+#define trace2_cmd_set_config(k, v) \
+	trace2_cmd_set_config_fl(__FILE__, __LINE__, (k), (v))
+
+/*
+ * Emit a 'child_start' event prior to spawning a child process.
+ *
+ * Before calling optionally set "cmd->trace2_child_class" to a string
+ * describing the type of the child process.  For example, "editor" or
+ * "pager".
+ */
+void trace2_child_start_fl(const char *file, int line,
+			   struct child_process *cmd);
+
+#define trace2_child_start(cmd) \
+	trace2_child_start_fl(__FILE__, __LINE__, (cmd))
+
+/*
+ * Emit a 'child_exit' event after the child process completes. 
+ */
+void trace2_child_exit_fl(const char *file, int line,
+			  struct child_process *cmd,
+			  int child_exit_code);
+
+#define trace2_child_exit(cmd, code) \
+	trace2_child_exit_fl(__FILE__, __LINE__, (cmd), (code))
+
+/*
+ * Emit an 'exec' event prior to calling one of exec(), execv(),
+ * execvp(), and etc.  On Unix-derived systems, this will be the
+ * last event emitted for the current process, unless the exec
+ * fails.  On Windows, exec() behaves like 'child_start' and a
+ * waitpid(), so additional events may be emitted.
+ *
+ * Returns the "exec_id".
+ */
+int trace2_exec_fl(const char *file, int line,
+		   const char *exe, const char **argv);
+
+#define trace2_exec(exe, argv) \
+	trace2_exec_fl(__FILE__, __LINE__, (exe), (argv))
+
+/*
+ * Emit an 'exec_result' when possible.  On Unix-derived systems,
+ * this should be called after exec() returns (which only happens
+ * when there is an error starting the new process).  On Windows,
+ * this should be called after the waitpid().
+ *
+ * The "exec_id" should be the value returned from trace2_exec().
+ */
+void trace2_exec_result_fl(const char *file, int line, int exec_id, int code);
+
+#define trace2_exec_result(id, code) \
+	trace2_exec_result_fl(__FILE__, __LINE__, (id), (code))
+
+/*
+ * Emit a 'thread_start' event.  This must be called from inside the
+ * thread-proc to set up the trace2 TLS data for the thread.
+ *
+ * Thread names should be descriptive, like "preload_index".
+ * Thread names will be decorated with an instance number automatically.
+ */
+void trace2_thread_start_fl(const char *file, int line,
+				 const char *thread_name);
+
+#define trace2_thread_start(thread_name) \
+	trace2_thread_start_fl(__FILE__, __LINE__, (thread_name))
+
+/*
+ * Emit a 'thread_exit' event.  This must be called from inside the
+ * thread-proc to report thread-specific data and cleanup TLS data
+ * for the thread.
+ */
+void trace2_thread_exit_fl(const char *file, int line);
+
+#define trace2_thread_exit() trace2_thread_exit_fl(__FILE__, __LINE__)
+
+/*
+ * Emit a 'param' event.
+ *
+ * Write a "<param> = <value>" pair describing some aspect of the
+ * run such as an important configuration setting or command line
+ * option that significantly changes command behavior.
+ */ 
+void trace2_def_param_fl(const char *file, int line,
+			 const char *param, const char *value);
+
+#define trace2_def_param(param, value) \
+	trace2_def_param_fl(__FILE__, __LINE__, (param), (value))
+
+/*
+ * Tell trace2 about a newly instantiated repo object and assign
+ * a trace2-repo-id to be used in subsequent activity events.
+ *
+ * Emits a 'worktree' event for this repo instance.
+ */
+void trace2_def_repo_fl(const char *file, int line,
+			struct repository *repo);
+
+#define trace2_def_repo(repo) \
+	trace2_def_repo_fl(__FILE__, __LINE__, repo)
+
+/*
+ * Emit a 'region_enter' event for <category>.<label> with optional
+ * repo-id and printf message.
+ *
+ * Enter a new nesting level on the current thread and remember the
+ * current time.  This controls the indenting of all subsequent events
+ * on this thread.
+ */
+void trace2_region_enter_fl(const char *file, int line,
+			    const char *category,
+			    const char *label,
+			    const struct repository *repo);
+
+#define trace2_region_enter(category, label, repo) \
+	trace2_region_enter_fl( \
+		__FILE__, __LINE__, (category), (label), (repo))
+
+void trace2_region_enter_printf_va_fl(const char *file, int line,
+				      const char *category,
+				      const char *label,
+				      const struct repository *repo,
+				      const char *fmt, va_list ap);
+
+#define trace2_region_enter_printf_va(category, label, repo, fmt, ap) \
+	trace2_region_enter_printf_va_fl( \
+		__FILE__, __LINE__, (category), (label), (repo), (fmt), (ap))
+
+void trace2_region_enter_printf_fl(const char *file, int line,
+				   const char *category, const char *label,
+				   const struct repository *repo,
+				   const char *fmt, ...);
+
+#ifdef HAVE_VARIADIC_MACROS
+#define trace2_region_enter_printf(category, label, repo, ...) \
+	trace2_region_enter_printf_fl( \
+		__FILE__, __LINE__, (category), (label), (repo), __VA_ARGS__)
+#else
+__attribute__((format (region_enter_printf, 4, 5)))
+void trace2_region_enter_printf(const char *category, const char *label,
+				const struct repository *repo,
+				const char *fmt, ...);
+#endif
+
+/*
+ * Emit a 'region_leave' event for <category>.<label> with optional
+ * repo-id and printf message.
+ *
+ * Leave current nesting level and report the elapsed time spent
+ * in this nesting level.
+ */
+void trace2_region_leave_fl(const char *file, int line,
+			    const char *category,
+			    const char *label,
+			    const struct repository *repo);
+
+#define trace2_region_leave(category, label, repo) \
+	trace2_region_leave_fl( \
+		__FILE__, __LINE__, (category), (label), (repo))
+
+void trace2_region_leave_printf_va_fl(const char *file, int line,
+				      const char *category,
+				      const char *label,
+				      const struct repository *repo,
+				      const char *fmt, va_list ap);
+
+#define trace2_region_leave_printf_va(category, label, repo, fmt, ap) \
+	trace2_region_leave_printf_va_fl( \
+		__FILE__, __LINE__, (category), (label), (repo), (fmt), (ap))
+
+void trace2_region_leave_printf_fl(const char *file, int line,
+				   const char *category, const char *label,
+				   const struct repository *repo,
+				   const char *fmt, ...);
+
+#ifdef HAVE_VARIADIC_MACROS
+#define trace2_region_leave_printf(category, label, repo, ...) \
+	trace2_region_leave_printf_fl( \
+		__FILE__, __LINE__, (category), (label), (repo), __VA_ARGS__)
+#else
+__attribute__((format (region_leave_printf, 4, 5)))
+void trace2_region_leave_printf(const char *category, const char *label,
+				const struct repository *repo,
+				const char *fmt, ...);
+#endif
+
+/*
+ * Emit a key-value pair 'data' event of the form <category>.<key> = <value>.
+ * This event implicitly contains information about thread, nesting region,
+ * and optional repo-id.
+ *
+ * On event-based TRACE2 targets, this generates a 'data' event suitable
+ * for post-processing.  On printf-based TRACE2 targets, this is converted
+ * into a fixed-format printf message.
+ */
+void trace2_data_string_fl(const char *file, int line,
+			   const char *category,
+			   const struct repository *repo,
+			   const char *key,
+			   const char *value);
+
+#define trace2_data_string(category, repo, key, value) \
+	trace2_data_string_fl( \
+		__FILE__, __LINE__, (category), (repo), (key), (value))
+
+void trace2_data_intmax_fl(const char *file, int line,
+			   const char *category,
+			   const struct repository *repo,
+			   const char *key,
+			   intmax_t value);
+
+#define trace2_data_intmax(category, repo, key, value) \
+	trace2_data_intmax_fl( \
+		__FILE__, __LINE__, (category), (repo), (key), (value))
+
+void trace2_data_json_fl(const char *file, int line,
+			 const char *category,
+			 const struct repository *repo,
+			 const char *key,
+			 const struct json_writer *jw);
+
+#define trace2_data_json(category, repo, key, value) \
+	trace2_data_json_fl( \
+		__FILE__, __LINE__, (category), (repo), (key), (value))
+
+/*
+ * Emit a 'printf' event.
+ *
+ * Write an arbitrary formatted message to the TRACE2 targets.  These
+ * text messages should be considered as human-readable strings without
+ * any formatting guidelines.  Post-processors may choose to ignore
+ * them.
+ */
+void trace2_printf_va_fl(const char *file, int line,
+			 const char *fmt, va_list ap);
+
+#define trace2_printf_va(fmt, ap) \
+	trace2_printf_va_fl(__FILE__, __LINE__, (fmt), (ap))
+
+void trace2_printf_fl(const char *file, int line, const char *fmt, ...);
+
+#ifdef HAVE_VARIADIC_MACROS
+#define trace2_printf(...) \
+	trace2_printf_fl(__FILE__, __LINE__, __VA_ARGS__)
+#else
+__attribute__((format (printf, 1, 2)))
+void trace2_printf(const char *fmt, ...);
+#endif
+
+#endif /* TRACE2_H */
diff --git a/trace2/tr2_cfg.c b/trace2/tr2_cfg.c
new file mode 100644
index 00000000000000..ef5aa159c200b3
--- /dev/null
+++ b/trace2/tr2_cfg.c
@@ -0,0 +1,92 @@
+#include "cache.h"
+#include "config.h"
+#include "tr2_cfg.h"
+
+#define TR2_ENVVAR_CFG_PARAM "GIT_TR2_CONFIG_PARAMS"
+
+static struct strbuf **tr2_cfg_patterns;
+static int tr2_cfg_count_patterns;
+static int tr2_cfg_loaded;
+
+/*
+ * Parse a string containing a comma-delimited list of config keys
+ * or wildcard patterns into a list of strbufs.
+ */
+static int tr2_cfg_load_patterns(void)
+{
+	struct strbuf **s;
+	const char *envvar;
+
+	if (tr2_cfg_loaded)
+		return tr2_cfg_count_patterns;
+	tr2_cfg_loaded = 1;
+
+	envvar = getenv(TR2_ENVVAR_CFG_PARAM);
+	if (!envvar || !*envvar)
+		return tr2_cfg_count_patterns;
+
+	tr2_cfg_patterns = strbuf_split_buf(envvar, strlen(envvar), ',', -1);
+	for (s = tr2_cfg_patterns; *s; s++) {
+		struct strbuf *buf = *s;
+
+		if (buf->len && buf->buf[buf->len - 1] == ',')
+			strbuf_setlen(buf, buf->len - 1);
+		strbuf_trim_trailing_newline(*s);
+		strbuf_trim(*s);
+	}
+
+	tr2_cfg_count_patterns = s - tr2_cfg_patterns;
+	return tr2_cfg_count_patterns;
+}
+
+void tr2_cfg_free_patterns(void)
+{
+	if (tr2_cfg_patterns)
+		strbuf_list_free(tr2_cfg_patterns);
+	tr2_cfg_count_patterns = 0;
+	tr2_cfg_loaded = 0;
+}
+
+struct tr2_cfg_data
+{
+	const char *file;
+	int line;
+};
+
+/*
+ * See if the given config key matches any of our patterns of interest.
+ */
+static int tr2_cfg_cb(const char *key, const char *value, void *d)
+{
+	struct strbuf **s;
+	struct tr2_cfg_data *data = (struct tr2_cfg_data *)d;
+
+	for (s = tr2_cfg_patterns; *s; s++) {
+		struct strbuf *buf = *s;
+		int wm = wildmatch(buf->buf, key, WM_CASEFOLD);
+		if (wm == WM_MATCH) {
+			trace2_def_param_fl(data->file, data->line, key, value);
+			return 0;
+		}
+	}
+
+	return 0;
+}
+
+void tr2_cfg_list_config_fl(const char *file, int line)
+{
+	struct tr2_cfg_data data = { file, line };
+
+	if (tr2_cfg_load_patterns() > 0)
+		read_early_config(tr2_cfg_cb, &data);
+}
+
+void tr2_cfg_set_fl(const char *file, int line,
+		    const char *key, const char *value)
+{
+	struct tr2_cfg_data data = { file, line };
+
+	if (tr2_cfg_load_patterns() > 0)
+		tr2_cfg_cb(key, value, &data);
+}
+
diff --git a/trace2/tr2_cfg.h b/trace2/tr2_cfg.h
new file mode 100644
index 00000000000000..1e3db7e496a782
--- /dev/null
+++ b/trace2/tr2_cfg.h
@@ -0,0 +1,23 @@
+#ifndef TR2_CFG_H
+#define TR2_CFG_H
+
+/*
+ * This file contains "private/protected" declarations for TRACE2.
+ */
+
+/*
+ * Iterate over all config settings and emit 'def_param' events for the
+ * "interesting" ones to TRACE2.
+ */
+void tr2_cfg_list_config_fl(const char *file, int line);
+
+/*
+ * Emit a "def_param" event for the given key/value pair IF we consider
+ * the key to be "interesting".
+ */
+void tr2_cfg_set_fl(const char *file, int line,
+		    const char *key, const char *value);
+
+void tr2_cfg_free_patterns(void);
+
+#endif /* TR2_CFG_H */
diff --git a/trace2/tr2_dst.c b/trace2/tr2_dst.c
new file mode 100644
index 00000000000000..e68c62629d2f5a
--- /dev/null
+++ b/trace2/tr2_dst.c
@@ -0,0 +1,87 @@
+#include "cache.h"
+#include "trace2/tr2_dst.h"
+
+/*
+ * This file contains "private/protected" declarations for TRACE2.
+ */
+
+void tr2_dst_trace_disable(struct tr2_dst *dst)
+{
+	if (dst->need_close)
+		close(dst->fd);
+	dst->fd = 0;
+	dst->initialized = 1;
+	dst->need_close = 0;
+}
+
+int tr2_dst_get_trace_fd(struct tr2_dst *dst)
+{
+	const char *trace;
+
+	/* don't open twice */
+	if (dst->initialized)
+		return dst->fd;
+
+	trace = getenv(dst->env_var_name);
+
+	if (!trace || !strcmp(trace, "") ||
+	    !strcmp(trace, "0") || !strcasecmp(trace, "false"))
+		dst->fd = 0;
+	else if (!strcmp(trace, "1") || !strcasecmp(trace, "true"))
+		dst->fd = STDERR_FILENO;
+	else if (strlen(trace) == 1 && isdigit(*trace))
+		dst->fd = atoi(trace);
+	else if (is_absolute_path(trace)) {
+		int fd = open(trace, O_WRONLY | O_APPEND | O_CREAT, 0666);
+		if (fd == -1) {
+			warning("could not open '%s' for tracing: %s",
+				trace, strerror(errno));
+			tr2_dst_trace_disable(dst);
+		} else {
+			dst->fd = fd;
+			dst->need_close = 1;
+		}
+	} else {
+		warning("unknown trace value for '%s': %s\n"
+			"         If you want to trace into a file, then please set %s\n"
+			"         to an absolute pathname (starting with /)",
+			dst->env_var_name, trace, dst->env_var_name);
+		tr2_dst_trace_disable(dst);
+	}
+
+	dst->initialized = 1;
+	return dst->fd;
+}
+
+int tr2_dst_trace_want(struct tr2_dst *dst)
+{
+	return !!tr2_dst_get_trace_fd(dst);
+}
+
+void tr2_dst_write_line(struct tr2_dst *dst, struct strbuf *buf_line)
+{
+	strbuf_complete_line(buf_line); /* ensure final NL on buffer */
+
+	/*
+	 * We do not use write_in_full() because we do not want
+	 * a short-write to try again.  We are using O_APPEND mode
+	 * files and the kernel handles the atomic seek+write. If
+	 * another thread or git process is concurrently writing to
+	 * this fd or file, our remainder-write may not be contiguous
+	 * with our initial write of this message.  And that will
+	 * confuse readers.  So just don't bother.
+	 *
+	 * It is assumed that TRACE2 messages are short enough that
+	 * the system can write them in 1 attempt and we won't see
+	 * a short-write.
+	 *
+	 * If we get an IO error, just close the trace dst.
+	 */
+
+	if (write(tr2_dst_get_trace_fd(dst),
+		  buf_line->buf, buf_line->len) < 0) {
+		warning("unable to write trace for '%s': %s",
+			dst->env_var_name, strerror(errno));
+		tr2_dst_trace_disable(dst);
+	}
+}
diff --git a/trace2/tr2_dst.h b/trace2/tr2_dst.h
new file mode 100644
index 00000000000000..90902a664cf62c
--- /dev/null
+++ b/trace2/tr2_dst.h
@@ -0,0 +1,34 @@
+#ifndef TR2_DST_H
+#define TR2_DST_H
+
+struct tr2_dst {
+	const char * const env_var_name;
+	int fd;
+	unsigned int initialized : 1;
+	unsigned int  need_close : 1;
+};
+
+/*
+ * Disable TRACE2 on the destination.  In TRACE2 a destination (DST)
+ * wraps a file descriptor; it is associated with a TARGET which
+ * defines the formatting.
+ */
+void tr2_dst_trace_disable(struct tr2_dst *dst);
+
+/*
+ * Return the file descriptor for the DST.
+ * If 0, the dst is closed or disabled.
+ */
+int tr2_dst_get_trace_fd(struct tr2_dst *dst);
+
+/*
+ * Return true if the DST is opened for writing.
+ */
+int tr2_dst_trace_want(struct tr2_dst *dst);
+
+/*
+ * Write a single line/message to the trace file.
+ */
+void tr2_dst_write_line(struct tr2_dst *dst, struct strbuf *buf_line);
+
+#endif /* TR2_DST_H */
diff --git a/trace2/tr2_sid.c b/trace2/tr2_sid.c
new file mode 100644
index 00000000000000..ed0d1161535579
--- /dev/null
+++ b/trace2/tr2_sid.c
@@ -0,0 +1,71 @@
+#include "cache.h"
+#include "trace2/tr2_sid.h"
+
+/*
+ * This file contains "private/protected" routines for TRACE2.
+ */
+
+#define TR2_ENVVAR_PARENT_SID "GIT_TR2_PARENT_SID"
+
+static struct strbuf tr2sid_buf = STRBUF_INIT;
+static int tr2sid_nr_git_parents;
+
+/*
+ * Compute a "unique" session id (SID) for the current process.  This allows
+ * all events from this process to have a single label (much like a PID).
+ *
+ * Export this into our environment so that all child processes inherit it.
+ *
+ * If we were started by another git instance, use our parent's SID as a
+ * prefix.  (This lets us track parent/child relationships even if there
+ * is an intermediate shell process.)
+ *
+ * Additionally, count the number of nested git processes.
+ */
+static void tr2_sid_compute(void)
+{
+	uint64_t us_now;
+	const char *parent_sid;
+
+	if (tr2sid_buf.len)
+		return;
+
+	parent_sid = getenv(TR2_ENVVAR_PARENT_SID);
+	if (parent_sid && *parent_sid) {
+		const char *p;
+		for (p = parent_sid; *p; p++)
+			if (*p == '/')
+				tr2sid_nr_git_parents++;
+
+		strbuf_addstr(&tr2sid_buf, parent_sid);
+		strbuf_addch(&tr2sid_buf, '/');
+		tr2sid_nr_git_parents++;
+	}
+
+	us_now = getnanotime() / 1000;
+	strbuf_addf(&tr2sid_buf, "%"PRIuMAX"-%"PRIdMAX,
+		    (uintmax_t)us_now, (intmax_t)getpid());
+
+	setenv(TR2_ENVVAR_PARENT_SID, tr2sid_buf.buf, 1);
+}
+
+const char *tr2_sid_get(void)
+{
+	if (!tr2sid_buf.len)
+		tr2_sid_compute();
+
+	return tr2sid_buf.buf;
+}
+
+int tr2_sid_depth(void)
+{
+	if (!tr2sid_buf.len)
+		tr2_sid_compute();
+
+	return tr2sid_nr_git_parents;
+}
+
+void tr2_sid_release(void)
+{
+	strbuf_release(&tr2sid_buf);
+}
diff --git a/trace2/tr2_sid.h b/trace2/tr2_sid.h
new file mode 100644
index 00000000000000..30fc14b894be02
--- /dev/null
+++ b/trace2/tr2_sid.h
@@ -0,0 +1,22 @@
+#ifndef TR2_SID_H
+#define TR2_SID_H
+
+/*
+ * This file contains "private/protected" declarations for TRACE2.
+ */
+
+/*
+ * Get our session id. Compute if necessary.
+ */
+const char *tr2_sid_get(void);
+
+/*
+ * Get our process depth.  A top-level git process invoked from the
+ * command line will have depth=0.  A child git process will have
+ * depth=1 and so on.
+ */
+int tr2_sid_depth(void);
+
+void tr2_sid_release(void);
+
+#endif /* TR2_SID_H */
diff --git a/trace2/tr2_tbuf.c b/trace2/tr2_tbuf.c
new file mode 100644
index 00000000000000..b79adcba371d97
--- /dev/null
+++ b/trace2/tr2_tbuf.c
@@ -0,0 +1,33 @@
+#include "cache.h"
+#include "tr2_tbuf.h"
+
+
+void tr2_tbuf_local_time(struct tr2_tbuf *tb)
+{
+	struct timeval tv;
+	struct tm tm;
+	time_t secs;
+
+	gettimeofday(&tv, NULL);
+	secs = tv.tv_sec;
+	localtime_r(&secs, &tm);
+
+	xsnprintf(tb->buf, sizeof(tb->buf), "%02d:%02d:%02d.%06ld",
+		  tm.tm_hour, tm.tm_min, tm.tm_sec, (long)tv.tv_usec);
+}
+
+void tr2_tbuf_utc_time(struct tr2_tbuf *tb)
+{
+	struct timeval tv;
+	struct tm tm;
+	time_t secs;
+
+	gettimeofday(&tv, NULL);
+	secs = tv.tv_sec;
+	gmtime_r(&secs, &tm);
+
+	xsnprintf(tb->buf, sizeof(tb->buf), "%4d-%02d-%02d %02d:%02d:%02d.%06ld",
+		  tm.tm_year+1900, tm.tm_mon+1, tm.tm_mday,
+		  tm.tm_hour, tm.tm_min, tm.tm_sec, (long)tv.tv_usec);
+}
+
diff --git a/trace2/tr2_tbuf.h b/trace2/tr2_tbuf.h
new file mode 100644
index 00000000000000..4c5626b7c5027e
--- /dev/null
+++ b/trace2/tr2_tbuf.h
@@ -0,0 +1,20 @@
+#ifndef TR2_TBUF_H
+#define TR2_TBUF_H
+
+/*
+ * This file contains "private/protected" declarations for TRACE2.
+ */
+
+/*
+ * A simple wrapper around a fixed buffer to avoid C syntax
+ * quirks and the need to pass around an additional size_t
+ * argument.
+ */
+struct tr2_tbuf {
+	char buf[32];
+};
+
+void tr2_tbuf_local_time(struct tr2_tbuf *tb);
+void tr2_tbuf_utc_time(struct tr2_tbuf *tb);
+
+#endif /* TR2_TBUF_H */
diff --git a/trace2/tr2_tgt.h b/trace2/tr2_tgt.h
new file mode 100644
index 00000000000000..e2140611624add
--- /dev/null
+++ b/trace2/tr2_tgt.h
@@ -0,0 +1,130 @@
+#ifndef TR2_TGT_H
+#define TR2_TGT_H
+
+/*
+ * This file contains "private/protected" declarations for TRACE2.
+ */
+
+/*
+ * Function prototypes for a TRACE2 "target" vtable.
+ */
+
+typedef int (tr2_tgt_init_t)(void);
+typedef void (tr2_tgt_term_t)(void);
+
+typedef void (tr2_tgt_evt_version_fl_t)
+	(const char *file, int line);
+
+typedef void (tr2_tgt_evt_start_fl_t)
+	(const char *file, int line, const char **argv);
+typedef void (tr2_tgt_evt_exit_fl_t)
+	(const char *file, int line, uint64_t us_elapsed_absolute, int code);
+typedef void (tr2_tgt_evt_signal_t)
+	(uint64_t us_elapsed_absolute, int signo);
+typedef void (tr2_tgt_evt_atexit_t)
+	(uint64_t us_elapsed_absolute, int code);
+
+typedef void (tr2_tgt_evt_error_va_fl_t)
+	(const char *file, int line, const char *fmt, va_list ap);
+
+typedef void (tr2_tgt_evt_command_path_fl_t)
+	(const char *file, int line, const char *command_path);
+typedef void (tr2_tgt_evt_command_verb_fl_t)
+	(const char *file, int line, const char *command_verb,
+	 const char *hierarchy);
+typedef void (tr2_tgt_evt_command_subverb_fl_t)
+	(const char *file, int line, const char *command_subverb);
+
+typedef void (tr2_tgt_evt_alias_fl_t)
+	(const char *file, int line, const char *alias, const char **argv);
+
+typedef void (tr2_tgt_evt_child_start_fl_t)
+	(const char *file, int line, uint64_t us_elapsed_absolute,
+	 const struct child_process *cmd);
+typedef void (tr2_tgt_evt_child_exit_fl_t)
+	(const char *file, int line, uint64_t us_elapsed_absolute, int cid,
+	 int pid, int code, uint64_t us_elapsed_child);
+
+typedef void (tr2_tgt_evt_thread_start_fl_t)
+	(const char *file, int line, uint64_t us_elapsed_absolute);
+typedef void (tr2_tgt_evt_thread_exit_fl_t)
+	(const char *file, int line, uint64_t us_elapsed_absolute,
+	 uint64_t us_elapsed_thread);
+
+typedef void (tr2_tgt_evt_exec_fl_t)
+	(const char *file, int line, uint64_t us_elapsed_absolute,
+	 int exec_id, const char *exe, const char **argv);
+typedef void (tr2_tgt_evt_exec_result_fl_t)
+	(const char *file, int line, uint64_t us_elapsed_absolute,
+	 int exec_id, int code);
+
+typedef void (tr2_tgt_evt_param_fl_t)
+	(const char *file, int line, const char *param, const char *value);
+
+typedef void (tr2_tgt_evt_repo_fl_t)
+	(const char *file, int line, const struct repository *repo);
+
+typedef void (tr2_tgt_evt_region_enter_printf_va_fl_t)
+	(const char *file, int line, uint64_t us_elapsed_absolute,
+	 const char *category, const char *label, const struct repository *repo,
+	 const char *fmt, va_list ap);
+typedef void (tr2_tgt_evt_region_leave_printf_va_fl_t)
+	(const char *file, int line, uint64_t us_elapsed_absolute,
+	 uint64_t us_elapsed_region, const char *category, const char *label,
+	 const struct repository *repo, const char *fmt, va_list ap);
+
+typedef void (tr2_tgt_evt_data_fl_t)
+	(const char *file, int line, uint64_t us_elapsed_absolute,
+	 uint64_t us_elapsed_region, const char *category,
+	 const struct repository *repo, const char *key, const char *value);
+typedef void (tr2_tgt_evt_data_json_fl_t)
+	(const char *file, int line, uint64_t us_elapsed_absolute,
+	 uint64_t us_elapsed_region, const char *category,
+	 const struct repository *repo,
+	 const char *key, const struct json_writer *value);
+
+typedef void (tr2_tgt_evt_printf_va_fl_t)
+	(const char *file, int line, uint64_t us_elapsed_absolute,
+	 const char *fmt, va_list ap);
+
+/*
+ * "vtable" for a TRACE2 target.  Use NULL if a target does not want
+ * to emit that message.
+ */
+struct tr2_tgt
+{
+	struct tr2_dst                          *pdst;
+
+	tr2_tgt_init_t                          *pfn_init;
+	tr2_tgt_term_t                          *pfn_term;
+
+	tr2_tgt_evt_version_fl_t                *pfn_version_fl;
+	tr2_tgt_evt_start_fl_t                  *pfn_start_fl;
+	tr2_tgt_evt_exit_fl_t                   *pfn_exit_fl;
+	tr2_tgt_evt_signal_t                    *pfn_signal;
+	tr2_tgt_evt_atexit_t                    *pfn_atexit;
+	tr2_tgt_evt_error_va_fl_t               *pfn_error_va_fl;
+	tr2_tgt_evt_command_path_fl_t           *pfn_command_path_fl;
+	tr2_tgt_evt_command_verb_fl_t           *pfn_command_verb_fl;
+	tr2_tgt_evt_command_subverb_fl_t        *pfn_command_subverb_fl;
+	tr2_tgt_evt_alias_fl_t                  *pfn_alias_fl;
+	tr2_tgt_evt_child_start_fl_t            *pfn_child_start_fl;
+	tr2_tgt_evt_child_exit_fl_t             *pfn_child_exit_fl;
+	tr2_tgt_evt_thread_start_fl_t           *pfn_thread_start_fl;
+	tr2_tgt_evt_thread_exit_fl_t            *pfn_thread_exit_fl;
+	tr2_tgt_evt_exec_fl_t                   *pfn_exec_fl;
+	tr2_tgt_evt_exec_result_fl_t            *pfn_exec_result_fl;
+	tr2_tgt_evt_param_fl_t                  *pfn_param_fl;
+	tr2_tgt_evt_repo_fl_t                   *pfn_repo_fl;
+	tr2_tgt_evt_region_enter_printf_va_fl_t *pfn_region_enter_printf_va_fl;
+	tr2_tgt_evt_region_leave_printf_va_fl_t *pfn_region_leave_printf_va_fl;
+	tr2_tgt_evt_data_fl_t                   *pfn_data_fl;
+	tr2_tgt_evt_data_json_fl_t              *pfn_data_json_fl;
+	tr2_tgt_evt_printf_va_fl_t              *pfn_printf_va_fl;
+};
+
+extern struct tr2_tgt tr2_tgt_event;
+extern struct tr2_tgt tr2_tgt_normal;
+extern struct tr2_tgt tr2_tgt_perf;
+
+#endif /* TR2_TGT_H */
diff --git a/trace2/tr2_tgt_event.c b/trace2/tr2_tgt_event.c
new file mode 100644
index 00000000000000..2cee2e24e64ba4
--- /dev/null
+++ b/trace2/tr2_tgt_event.c
@@ -0,0 +1,590 @@
+#include "cache.h"
+#include "config.h"
+#include "json-writer.h"
+#include "run-command.h"
+#include "version.h"
+#include "trace2/tr2_dst.h"
+#include "trace2/tr2_tbuf.h"
+#include "trace2/tr2_sid.h"
+#include "trace2/tr2_tgt.h"
+#include "trace2/tr2_tls.h"
+
+/*
+ * This file contains "private/protected" declarations for TRACE2.
+ */
+
+static struct tr2_dst tr2dst_event  = { "GIT_TR2_EVENT", 0, 0, 0 };
+
+/*
+ * The version number of the JSON data generated by the EVENT target
+ * in this source file.  Update this if you make a significant change
+ * to the JSON fields or message structure.  You probably do not need
+ * to update this if you just add another call to one of the existing
+ * TRACE2 API methods.
+ */
+#define TR2_EVENT_VERSION "1"
+
+/*
+ * Region nesting limit for messages written to the event target.
+ *
+ * The "region_enter" and "region_leave" messages (especially recursive
+ * messages such as those produced while diving the worktree or index)
+ * are primarily intended for the performance target during debugging.
+ *
+ * Some of the outer-most messages, however, may be of interest to the
+ * event target.  Set this environment variable to a larger integer for
+ * more detail in the event target.
+ */
+#define TR2_ENVVAR_EVENT_NESTING "GIT_TR2_EVENT_NESTING"
+static int tr2env_event_nesting_wanted = 2;
+
+static int fn_init(void)
+{
+	int want = tr2_dst_trace_want(&tr2dst_event);
+	int want_nesting;
+	char *nesting;
+
+	if (!want)
+		return want;
+
+	nesting = getenv(TR2_ENVVAR_EVENT_NESTING);
+	if (nesting && ((want_nesting = atoi(nesting)) > 0))
+		tr2env_event_nesting_wanted = want_nesting;
+
+	return want;
+}
+
+static void fn_term(void)
+{
+	tr2_dst_trace_disable(&tr2dst_event);
+}
+
+/*
+ * Append common key-value pairs to the currently open JSON object.
+ *     "event:"<event_name>"
+ *      "sid":"<sid>"
+ *   "thread":"<thread_name>"
+ *     "time":"<time>"
+ *     "file":"<filename>"
+ *     "line":<line_number>
+ *     "repo":<repo_id>
+ */
+static void event_fmt_prepare(const char *event_name,
+			      const char *file, int line,
+			      const struct repository *repo,
+			      struct json_writer *jw)
+{
+	struct tr2tls_thread_ctx *ctx = tr2tls_get_self();
+	struct tr2_tbuf tb_now;
+
+	jw_object_string(jw, "event", event_name);
+	jw_object_string(jw, "sid", tr2_sid_get());
+	jw_object_string(jw, "thread", ctx->thread_name.buf);
+
+	tr2_tbuf_utc_time(&tb_now);
+	jw_object_string(jw, "time", tb_now.buf);
+
+	if (file && *file) {
+		jw_object_string(jw, "file", file);
+		jw_object_intmax(jw, "line", line);
+	}
+
+	if (repo)
+		jw_object_intmax(jw, "repo", repo->trace2_repo_id);
+}
+
+static void fn_version_fl(const char *file, int line)
+{
+	const char *event_name = "version";
+	struct json_writer jw = JSON_WRITER_INIT;
+
+	jw_object_begin(&jw, 0);
+	event_fmt_prepare(event_name, file, line, NULL, &jw);
+	jw_object_string(&jw, "evt", TR2_EVENT_VERSION);
+	jw_object_string(&jw, "exe", git_version_string);
+	jw_end(&jw);
+
+	tr2_dst_write_line(&tr2dst_event, &jw.json);
+	jw_release(&jw);
+}
+
+static void fn_start_fl(const char *file, int line, const char **argv)
+{
+	const char *event_name = "start";
+	struct json_writer jw = JSON_WRITER_INIT;
+
+	jw_object_begin(&jw, 0);
+	event_fmt_prepare(event_name, file, line, NULL, &jw);
+	jw_object_inline_begin_array(&jw, "argv");
+	jw_array_argv(&jw, argv);
+	jw_end(&jw);
+	jw_end(&jw);
+
+	tr2_dst_write_line(&tr2dst_event, &jw.json);
+	jw_release(&jw);
+}
+
+static void fn_exit_fl(const char *file, int line,
+		       uint64_t us_elapsed_absolute, int code)
+{
+	const char *event_name = "exit";
+	struct json_writer jw = JSON_WRITER_INIT;
+	double t_abs = (double)us_elapsed_absolute / 1000000.0;
+
+	jw_object_begin(&jw, 0);
+	event_fmt_prepare(event_name, file, line, NULL, &jw);
+	jw_object_double(&jw, "t_abs", 6, t_abs);
+	jw_object_intmax(&jw, "code", code);
+	jw_end(&jw);
+
+	tr2_dst_write_line(&tr2dst_event, &jw.json);
+	jw_release(&jw);
+}
+
+static void fn_signal(uint64_t us_elapsed_absolute, int signo)
+{
+	const char *event_name = "signal";
+	struct json_writer jw = JSON_WRITER_INIT;
+	double t_abs = (double)us_elapsed_absolute / 1000000.0;
+
+	jw_object_begin(&jw, 0);
+	event_fmt_prepare(event_name, __FILE__, __LINE__, NULL, &jw);
+	jw_object_double(&jw, "t_abs", 6, t_abs);
+	jw_object_intmax(&jw, "signo", signo);
+	jw_end(&jw);
+
+	tr2_dst_write_line(&tr2dst_event, &jw.json);
+	jw_release(&jw);
+}
+
+static void fn_atexit(uint64_t us_elapsed_absolute, int code)
+{
+	const char *event_name = "atexit";
+	struct json_writer jw = JSON_WRITER_INIT;
+	double t_abs = (double)us_elapsed_absolute / 1000000.0;
+
+	jw_object_begin(&jw, 0);
+	event_fmt_prepare(event_name, __FILE__, __LINE__, NULL, &jw);
+	jw_object_double(&jw, "t_abs", 6, t_abs);
+	jw_object_intmax(&jw, "code", code);
+	jw_end(&jw);
+
+	tr2_dst_write_line(&tr2dst_event, &jw.json);
+	jw_release(&jw);
+}
+
+static void maybe_add_string_va(struct json_writer *jw,
+				const char *field_name,
+				const char *fmt, va_list ap)
+{
+	if (fmt && *fmt && ap) {
+		va_list copy_ap;
+		struct strbuf buf = STRBUF_INIT;
+
+		va_copy(copy_ap, ap);
+		strbuf_vaddf(&buf, fmt, copy_ap);
+		va_end(copy_ap);
+
+		jw_object_string(jw, field_name, buf.buf);
+		strbuf_release(&buf);
+		return;
+	}
+
+	if (fmt && *fmt) {
+		jw_object_string(jw, field_name, fmt);
+		return;
+	}
+}
+
+static void fn_error_va_fl(const char *file, int line,
+			   const char *fmt, va_list ap)
+{
+	const char *event_name = "error";
+	struct json_writer jw = JSON_WRITER_INIT;
+
+	jw_object_begin(&jw, 0);
+	event_fmt_prepare(event_name, file, line, NULL, &jw);
+	maybe_add_string_va(&jw, "msg", fmt, ap);
+	/*
+	 * Also emit the format string as a field in case
+	 * post-processors want to aggregate common error
+	 * messages by type without argument fields (such
+	 * as pathnames or branch names) cluttering it up.
+	 */
+	if (fmt && *fmt)
+		jw_object_string(&jw, "fmt", fmt);
+	jw_end(&jw);
+
+	tr2_dst_write_line(&tr2dst_event, &jw.json);
+	jw_release(&jw);
+}
+
+static void fn_command_path_fl(const char *file, int line,
+			       const char *pathname)
+{
+	const char *event_name = "cmd_path";
+	struct json_writer jw = JSON_WRITER_INIT;
+
+	jw_object_begin(&jw, 0);
+	event_fmt_prepare(event_name, file, line, NULL, &jw);
+	jw_object_string(&jw, "path", pathname);
+	jw_end(&jw);
+
+	tr2_dst_write_line(&tr2dst_event, &jw.json);
+	jw_release(&jw);
+}
+
+static void fn_command_verb_fl(const char *file, int line,
+			       const char *command_verb,
+			       const char *verb_hierarchy)
+{
+	const char *event_name = "cmd_verb";
+	struct json_writer jw = JSON_WRITER_INIT;
+
+	jw_object_begin(&jw, 0);
+	event_fmt_prepare(event_name, file, line, NULL, &jw);
+	jw_object_string(&jw, "name", command_verb);
+	if (verb_hierarchy && *verb_hierarchy)
+		jw_object_string(&jw, "hierarchy", verb_hierarchy);
+	jw_end(&jw);
+
+	tr2_dst_write_line(&tr2dst_event, &jw.json);
+	jw_release(&jw);
+}
+
+static void fn_command_subverb_fl(const char *file, int line,
+			       const char *command_subverb)
+{
+	const char *event_name = "cmd_subverb";
+	struct json_writer jw = JSON_WRITER_INIT;
+
+	jw_object_begin(&jw, 0);
+	event_fmt_prepare(event_name, file, line, NULL, &jw);
+	jw_object_string(&jw, "name", command_subverb);
+	jw_end(&jw);
+
+	tr2_dst_write_line(&tr2dst_event, &jw.json);
+	jw_release(&jw);
+}
+
+static void fn_alias_fl(const char *file, int line,
+			const char *alias, const char **argv)
+{
+	const char *event_name = "alias";
+	struct json_writer jw = JSON_WRITER_INIT;
+
+	jw_object_begin(&jw, 0);
+	event_fmt_prepare(event_name, file, line, NULL, &jw);
+	jw_object_string(&jw, "alias", alias);
+	jw_object_inline_begin_array(&jw, "argv");
+	jw_array_argv(&jw, argv);
+	jw_end(&jw);
+	jw_end(&jw);
+
+	tr2_dst_write_line(&tr2dst_event, &jw.json);
+	jw_release(&jw);
+}
+
+static void fn_child_start_fl(const char *file, int line,
+			      uint64_t us_elapsed_absolute,
+			      const struct child_process *cmd)
+{
+	const char *event_name = "child_start";
+	struct json_writer jw = JSON_WRITER_INIT;
+
+	jw_object_begin(&jw, 0);
+	event_fmt_prepare(event_name, file, line, NULL, &jw);
+	jw_object_intmax(&jw, "child_id", cmd->trace2_child_id);
+	if (cmd->trace2_hook_name) {
+		jw_object_string(&jw, "child_class", "hook");
+		jw_object_string(&jw, "hook_name", cmd->trace2_hook_name);
+	} else {
+		const char *child_class = ((cmd->trace2_child_class) ?
+					   cmd->trace2_child_class : "?");
+		jw_object_string(&jw, "child_class", child_class);
+	}
+	if (cmd->dir)
+		jw_object_string(&jw, "cd", cmd->dir);
+	jw_object_bool(&jw, "use_shell", cmd->use_shell);
+	jw_object_inline_begin_array(&jw, "argv");
+	if (cmd->git_cmd)
+		jw_array_string(&jw, "git");
+	jw_array_argv(&jw, cmd->argv);
+	jw_end(&jw);
+	jw_end(&jw);
+
+	tr2_dst_write_line(&tr2dst_event, &jw.json);
+	jw_release(&jw);
+}
+
+static void fn_child_exit_fl(const char *file, int line,
+			     uint64_t us_elapsed_absolute,
+			     int cid, int pid, int code,
+			     uint64_t us_elapsed_child)
+{
+	const char *event_name = "child_exit";
+	struct json_writer jw = JSON_WRITER_INIT;
+	double t_rel = (double)us_elapsed_child / 1000000.0;
+
+	jw_object_begin(&jw, 0);
+	event_fmt_prepare(event_name, file, line, NULL, &jw);
+	jw_object_intmax(&jw, "child_id", cid);
+	jw_object_intmax(&jw, "pid", pid);
+	jw_object_intmax(&jw, "code", code);
+	jw_object_double(&jw, "t_rel", 6, t_rel);
+	jw_end(&jw);
+
+	tr2_dst_write_line(&tr2dst_event, &jw.json);
+
+	jw_release(&jw);
+}
+
+static void fn_thread_start_fl(const char *file, int line,
+			       uint64_t us_elapsed_absolute)
+{
+	const char *event_name = "thread_start";
+	struct json_writer jw = JSON_WRITER_INIT;
+
+	jw_object_begin(&jw, 0);
+	event_fmt_prepare(event_name, file, line, NULL, &jw);
+	jw_end(&jw);
+
+	tr2_dst_write_line(&tr2dst_event, &jw.json);
+	jw_release(&jw);
+}
+
+static void fn_thread_exit_fl(const char *file, int line,
+			      uint64_t us_elapsed_absolute,
+			      uint64_t us_elapsed_thread)
+{
+	const char *event_name = "thread_exit";
+	struct json_writer jw = JSON_WRITER_INIT;
+	double t_rel = (double)us_elapsed_thread / 1000000.0;
+
+	jw_object_begin(&jw, 0);
+	event_fmt_prepare(event_name, file, line, NULL, &jw);
+	jw_object_double(&jw, "t_rel", 6, t_rel);
+	jw_end(&jw);
+
+	tr2_dst_write_line(&tr2dst_event, &jw.json);
+	jw_release(&jw);
+}
+
+static void fn_exec_fl(const char *file, int line,
+		       uint64_t us_elapsed_absolute,
+		       int exec_id, const char *exe, const char **argv)
+{
+	const char *event_name = "exec";
+	struct json_writer jw = JSON_WRITER_INIT;
+
+	jw_object_begin(&jw, 0);
+	event_fmt_prepare(event_name, file, line, NULL, &jw);
+	jw_object_intmax(&jw, "exec_id", exec_id);
+	if (exe)
+		jw_object_string(&jw, "exe", exe);
+	jw_object_inline_begin_array(&jw, "argv");
+	jw_array_argv(&jw, argv);
+	jw_end(&jw);
+	jw_end(&jw);
+
+	tr2_dst_write_line(&tr2dst_event, &jw.json);
+	jw_release(&jw);
+}
+
+static void fn_exec_result_fl(const char *file, int line,
+			      uint64_t us_elapsed_absolute,
+			      int exec_id, int code)
+{
+	const char *event_name = "exec_result";
+	struct json_writer jw = JSON_WRITER_INIT;
+
+	jw_object_begin(&jw, 0);
+	event_fmt_prepare(event_name, file, line, NULL, &jw);
+	jw_object_intmax(&jw, "exec_id", exec_id);
+	jw_object_intmax(&jw, "code", code);
+	jw_end(&jw);
+
+	tr2_dst_write_line(&tr2dst_event, &jw.json);
+	jw_release(&jw);
+}
+
+static void fn_param_fl(const char *file, int line,
+			const char *param, const char *value)
+{
+	const char *event_name = "def_param";
+	struct json_writer jw = JSON_WRITER_INIT;
+
+	jw_object_begin(&jw, 0);
+	event_fmt_prepare(event_name, file, line, NULL, &jw);
+	jw_object_string(&jw, "param", param);
+	jw_object_string(&jw, "value", value);
+	jw_end(&jw);
+
+	tr2_dst_write_line(&tr2dst_event, &jw.json);
+	jw_release(&jw);
+}
+
+static void fn_repo_fl(const char *file, int line,
+		       const struct repository *repo)
+{
+	const char *event_name = "def_repo";
+	struct json_writer jw = JSON_WRITER_INIT;
+
+	jw_object_begin(&jw, 0);
+	event_fmt_prepare(event_name, file, line, repo, &jw);
+	jw_object_string(&jw, "worktree", repo->worktree);
+	jw_end(&jw);
+
+	tr2_dst_write_line(&tr2dst_event, &jw.json);
+	jw_release(&jw);
+}
+
+static void fn_region_enter_printf_va_fl(const char *file, int line,
+					 uint64_t us_elapsed_absolute,
+					 const char *category,
+					 const char *label,
+					 const struct repository *repo,
+					 const char *fmt, va_list ap)
+{
+	const char *event_name = "region_enter";
+	struct tr2tls_thread_ctx *ctx = tr2tls_get_self();
+	if (ctx->nr_open_regions <= tr2env_event_nesting_wanted) {
+		struct json_writer jw = JSON_WRITER_INIT;
+
+		jw_object_begin(&jw, 0);
+		event_fmt_prepare(
+			event_name, file, line, repo, &jw);
+		jw_object_intmax(&jw, "nesting", ctx->nr_open_regions);
+		if (category)
+			jw_object_string(&jw, "category", category);
+		if (label)
+			jw_object_string(&jw, "label", label);
+		maybe_add_string_va(&jw, "msg", fmt, ap);
+		jw_end(&jw);
+
+		tr2_dst_write_line(&tr2dst_event, &jw.json);
+		jw_release(&jw);
+	}
+}
+
+static void fn_region_leave_printf_va_fl(const char *file, int line,
+					 uint64_t us_elapsed_absolute,
+					 uint64_t us_elapsed_region,
+					 const char *category,
+					 const char *label,
+					 const struct repository *repo,
+					 const char *fmt, va_list ap)
+{
+	const char *event_name = "region_leave";
+	struct tr2tls_thread_ctx *ctx = tr2tls_get_self();
+	if (ctx->nr_open_regions <= tr2env_event_nesting_wanted) {
+		struct json_writer jw = JSON_WRITER_INIT;
+		double t_rel = (double)us_elapsed_region / 1000000.0;
+
+		jw_object_begin(&jw, 0);
+		event_fmt_prepare(event_name, file, line, repo, &jw);
+		jw_object_double(&jw, "t_rel", 6, t_rel);
+		jw_object_intmax(&jw, "nesting", ctx->nr_open_regions);
+		if (category)
+			jw_object_string(&jw, "category", category);
+		if (label)
+			jw_object_string(&jw, "label", label);
+		maybe_add_string_va(&jw, "msg", fmt, ap);
+		jw_end(&jw);
+
+		tr2_dst_write_line(&tr2dst_event, &jw.json);
+		jw_release(&jw);
+	}
+}
+
+static void fn_data_fl(const char *file, int line,
+		       uint64_t us_elapsed_absolute,
+		       uint64_t us_elapsed_region,
+		       const char *category,
+		       const struct repository *repo,
+		       const char *key,
+		       const char *value)
+{
+	const char *event_name = "data";
+	struct tr2tls_thread_ctx *ctx = tr2tls_get_self();
+	if (ctx->nr_open_regions <= tr2env_event_nesting_wanted) {
+		struct json_writer jw = JSON_WRITER_INIT;
+		double t_abs = (double)us_elapsed_absolute / 1000000.0;
+		double t_rel = (double)us_elapsed_region / 1000000.0;
+
+		jw_object_begin(&jw, 0);
+		event_fmt_prepare(event_name, file, line, repo, &jw);
+		jw_object_double(&jw, "t_abs", 6, t_abs);
+		jw_object_double(&jw, "t_rel", 6, t_rel);
+		jw_object_intmax(&jw, "nesting", ctx->nr_open_regions);
+		jw_object_string(&jw, "category", category);
+		jw_object_string(&jw, "key", key);
+		jw_object_string(&jw, "value", value);
+		jw_end(&jw);
+
+		tr2_dst_write_line(&tr2dst_event, &jw.json);
+		jw_release(&jw);
+	}
+}
+
+static void fn_data_json_fl(const char *file, int line,
+			    uint64_t us_elapsed_absolute,
+			    uint64_t us_elapsed_region,
+			    const char *category,
+			    const struct repository *repo,
+			    const char *key,
+			    const struct json_writer *value)
+{
+	const char *event_name = "data_json";
+	struct tr2tls_thread_ctx *ctx = tr2tls_get_self();
+	if (ctx->nr_open_regions <= tr2env_event_nesting_wanted) {
+		struct json_writer jw = JSON_WRITER_INIT;
+		double t_abs = (double)us_elapsed_absolute / 1000000.0;
+		double t_rel = (double)us_elapsed_region / 1000000.0;
+
+		jw_object_begin(&jw, 0);
+		event_fmt_prepare(event_name, file, line, repo, &jw);
+		jw_object_double(&jw, "t_abs", 6, t_abs);
+		jw_object_double(&jw, "t_rel", 6, t_rel);
+		jw_object_intmax(&jw, "nesting", ctx->nr_open_regions);
+		jw_object_string(&jw, "category", category);
+		jw_object_string(&jw, "key", key);
+		jw_object_sub_jw(&jw, "value", value);
+		jw_end(&jw);
+
+		tr2_dst_write_line(&tr2dst_event, &jw.json);
+		jw_release(&jw);
+	}
+}
+
+struct tr2_tgt tr2_tgt_event =
+{
+	&tr2dst_event,
+
+	fn_init,
+	fn_term,
+
+	fn_version_fl,
+	fn_start_fl,
+	fn_exit_fl,
+	fn_signal,
+	fn_atexit,
+	fn_error_va_fl,
+	fn_command_path_fl,
+	fn_command_verb_fl,
+	fn_command_subverb_fl,
+	fn_alias_fl,
+	fn_child_start_fl,
+	fn_child_exit_fl,
+	fn_thread_start_fl,
+	fn_thread_exit_fl,
+	fn_exec_fl,
+	fn_exec_result_fl,
+	fn_param_fl,
+	fn_repo_fl,
+	fn_region_enter_printf_va_fl,
+	fn_region_leave_printf_va_fl,
+	fn_data_fl,
+	fn_data_json_fl,
+	NULL, /* printf */
+};
diff --git a/trace2/tr2_tgt_normal.c b/trace2/tr2_tgt_normal.c
new file mode 100644
index 00000000000000..b09ae3f994cca1
--- /dev/null
+++ b/trace2/tr2_tgt_normal.c
@@ -0,0 +1,335 @@
+#include "cache.h"
+#include "config.h"
+#include "run-command.h"
+#include "quote.h"
+#include "version.h"
+#include "trace2/tr2_dst.h"
+#include "trace2/tr2_tbuf.h"
+#include "trace2/tr2_tgt.h"
+#include "trace2/tr2_tls.h"
+
+/*
+ * This file contains "private/protected" declarations for TRACE2.
+ */
+
+static struct tr2_dst tr2dst_normal = { "GIT_TR2", 0, 0, 0 };
+
+/*
+ * Set this environment variable to true to omit the "<time> <file>:<line>"
+ * fields from each line written to the builtin normal target.
+ *
+ * Unit tests may want to use this to help with testing.
+ */
+#define TR2_ENVVAR_NORMAL_BARE "GIT_TR2_BARE"
+static int tr2env_normal_bare;
+
+#define TR2FMT_NORMAL_FL_WIDTH       (50)
+
+static int fn_init(void)
+{
+	int want = tr2_dst_trace_want(&tr2dst_normal);
+	int want_bare;
+	char *bare;
+
+	if (!want)
+		return want;
+
+	bare = getenv(TR2_ENVVAR_NORMAL_BARE);
+	if (bare && *bare &&
+	    ((want_bare = git_parse_maybe_bool(bare)) != -1))
+		tr2env_normal_bare = want_bare;
+
+	return want;
+}
+
+static void fn_term(void)
+{
+	tr2_dst_trace_disable(&tr2dst_normal);
+}
+
+static void normal_fmt_prepare(const char *file, int line, struct strbuf *buf)
+{
+	strbuf_setlen(buf,0);
+
+	if (!tr2env_normal_bare) {
+		struct tr2_tbuf tb_now;
+
+		tr2_tbuf_local_time(&tb_now);
+		strbuf_addstr(buf, tb_now.buf);
+		strbuf_addch(buf, ' ');
+
+		if (file && *file)
+			strbuf_addf(buf, "%s:%d ", file, line);
+		while (buf->len < TR2FMT_NORMAL_FL_WIDTH)
+			strbuf_addch(buf, ' ');
+	}
+}
+
+static void normal_io_write_fl(const char *file, int line,
+			       const struct strbuf *buf_payload)
+{
+	struct strbuf buf_line = STRBUF_INIT;
+
+	normal_fmt_prepare(file, line, &buf_line);
+	strbuf_addbuf(&buf_line, buf_payload);
+	tr2_dst_write_line(&tr2dst_normal, &buf_line);
+	strbuf_release(&buf_line);
+}
+
+static void fn_version_fl(const char *file, int line)
+{
+	struct strbuf buf_payload = STRBUF_INIT;
+
+	strbuf_addf(&buf_payload, "version %s", git_version_string);
+	normal_io_write_fl(file, line, &buf_payload);
+	strbuf_release(&buf_payload);
+}
+
+static void fn_start_fl(const char *file, int line, const char **argv)
+{
+	struct strbuf buf_payload = STRBUF_INIT;
+
+	strbuf_addstr(&buf_payload, "start ");
+	sq_quote_argv_pretty(&buf_payload, argv);
+	normal_io_write_fl(file, line, &buf_payload);
+	strbuf_release(&buf_payload);
+}
+
+static void fn_exit_fl(const char *file, int line,
+		       uint64_t us_elapsed_absolute, int code)
+{
+	struct strbuf buf_payload = STRBUF_INIT;
+	double elapsed = (double)us_elapsed_absolute / 1000000.0;
+
+	strbuf_addf(&buf_payload, "exit elapsed:%.6f code:%d",
+		    elapsed, code);
+	normal_io_write_fl(file, line, &buf_payload);
+	strbuf_release(&buf_payload);
+}
+
+static void fn_signal(uint64_t us_elapsed_absolute, int signo)
+{
+	struct strbuf buf_payload = STRBUF_INIT;
+	double elapsed = (double)us_elapsed_absolute / 1000000.0;
+
+	strbuf_addf(&buf_payload, "signal elapsed:%.6f code:%d",
+		    elapsed, signo);
+	normal_io_write_fl(__FILE__, __LINE__, &buf_payload);
+	strbuf_release(&buf_payload);
+}
+
+static void fn_atexit(uint64_t us_elapsed_absolute, int code)
+{
+	struct strbuf buf_payload = STRBUF_INIT;
+	double elapsed = (double)us_elapsed_absolute / 1000000.0;
+
+	strbuf_addf(&buf_payload, "atexit elapsed:%.6f code:%d",
+		    elapsed, code);
+	normal_io_write_fl(__FILE__, __LINE__, &buf_payload);
+	strbuf_release(&buf_payload);
+}
+
+static void maybe_append_string_va(struct strbuf *buf,
+				   const char *fmt, va_list ap)
+{
+	if (fmt && *fmt && ap) {
+		va_list copy_ap;
+
+		va_copy(copy_ap, ap);
+		strbuf_vaddf(buf, fmt, copy_ap);
+		va_end(copy_ap);
+		return;
+	}
+
+	if (fmt && *fmt) {
+		strbuf_addstr(buf, fmt);
+		return;
+	}
+}
+
+static void fn_error_va_fl(const char *file, int line,
+			   const char *fmt, va_list ap)
+{
+	struct strbuf buf_payload = STRBUF_INIT;
+
+	strbuf_addstr(&buf_payload, "error ");
+	maybe_append_string_va(&buf_payload, fmt, ap);
+	normal_io_write_fl(file, line, &buf_payload);
+	strbuf_release(&buf_payload);
+}
+
+static void fn_command_path_fl(const char *file, int line,
+			       const char *pathname)
+{
+	struct strbuf buf_payload = STRBUF_INIT;
+
+	strbuf_addf(&buf_payload, "cmd_path %s", pathname);
+	normal_io_write_fl(file, line, &buf_payload);
+	strbuf_release(&buf_payload);
+}
+
+static void fn_command_verb_fl(const char *file, int line,
+			       const char *command_verb,
+			       const char *verb_hierarchy)
+{
+	struct strbuf buf_payload = STRBUF_INIT;
+
+	strbuf_addf(&buf_payload, "cmd_verb %s", command_verb);
+	if (verb_hierarchy && *verb_hierarchy)
+		strbuf_addf(&buf_payload, " (%s)", verb_hierarchy);
+	normal_io_write_fl(file, line, &buf_payload);
+	strbuf_release(&buf_payload);
+}
+
+static void fn_command_subverb_fl(const char *file, int line,
+			       const char *command_subverb)
+{
+	struct strbuf buf_payload = STRBUF_INIT;
+
+	strbuf_addf(&buf_payload, "cmd_subverb %s", command_subverb);
+	normal_io_write_fl(file, line, &buf_payload);
+	strbuf_release(&buf_payload);
+}
+
+static void fn_alias_fl(const char *file, int line, const char *alias,
+			const char **argv)
+{
+	struct strbuf buf_payload = STRBUF_INIT;
+
+	strbuf_addf(&buf_payload, "alias %s ->", alias);
+	sq_quote_argv_pretty(&buf_payload, argv);
+	normal_io_write_fl(file, line, &buf_payload);
+	strbuf_release(&buf_payload);
+}
+
+static void fn_child_start_fl(const char *file, int line,
+			      uint64_t us_elapsed_absolute,
+			      const struct child_process *cmd)
+{
+	struct strbuf buf_payload = STRBUF_INIT;
+
+	strbuf_addf(&buf_payload, "child_start[%d] ", cmd->trace2_child_id);
+
+	if (cmd->dir) {
+		strbuf_addstr(&buf_payload, " cd");
+		sq_quote_buf_pretty(&buf_payload, cmd->dir);
+		strbuf_addstr(&buf_payload, "; ");
+	}
+
+	/*
+	 * TODO if (cmd->env) { Consider dumping changes to environment. }
+	 * See trace_add_env() in run-command.c as used by original trace.c
+	 */
+
+	if (cmd->git_cmd)
+		strbuf_addstr(&buf_payload, "git");
+	sq_quote_argv_pretty(&buf_payload, cmd->argv);
+
+	normal_io_write_fl(file, line, &buf_payload);
+	strbuf_release(&buf_payload);
+}
+
+static void fn_child_exit_fl(const char *file, int line,
+			     uint64_t us_elapsed_absolute,
+			     int cid, int pid, int code,
+			     uint64_t us_elapsed_child)
+{
+	struct strbuf buf_payload = STRBUF_INIT;
+	double elapsed = (double)us_elapsed_child / 1000000.0;
+
+	strbuf_addf(&buf_payload, "child_exit[%d] pid:%d code:%d elapsed:%.6f",
+		    cid, pid, code, elapsed);
+	normal_io_write_fl(file, line, &buf_payload);
+	strbuf_release(&buf_payload);
+}
+
+static void fn_exec_fl(const char *file, int line,
+		       uint64_t us_elapsed_absolute,
+		       int exec_id, const char *exe, const char **argv)
+{
+	struct strbuf buf_payload = STRBUF_INIT;
+
+	strbuf_addf(&buf_payload, "exec[%d] ", exec_id);
+	if (exe)
+		strbuf_addstr(&buf_payload, exe);
+	sq_quote_argv_pretty(&buf_payload, argv);
+	normal_io_write_fl(file, line, &buf_payload);
+	strbuf_release(&buf_payload);
+}
+
+static void fn_exec_result_fl(const char *file, int line,
+			      uint64_t us_elapsed_absolute,
+			      int exec_id, int code)
+{
+	struct strbuf buf_payload = STRBUF_INIT;
+
+	strbuf_addf(&buf_payload, "exec_result[%d] code:%d", exec_id, code);
+	if (code > 0)
+		strbuf_addf(&buf_payload, " err:%s", strerror(code));
+	normal_io_write_fl(file, line, &buf_payload);
+	strbuf_release(&buf_payload);
+}
+
+static void fn_param_fl(const char *file, int line, const char *param,
+			const char *value)
+{
+	struct strbuf buf_payload = STRBUF_INIT;
+
+	strbuf_addf(&buf_payload, "def_param %s=%s", param, value);
+	normal_io_write_fl(file, line, &buf_payload);
+	strbuf_release(&buf_payload);
+}
+
+static void fn_repo_fl(const char *file, int line,
+		       const struct repository *repo)
+{
+	struct strbuf buf_payload = STRBUF_INIT;
+
+	strbuf_addstr(&buf_payload, "worktree ");
+	sq_quote_buf_pretty(&buf_payload, repo->worktree);
+	normal_io_write_fl(file, line, &buf_payload);
+	strbuf_release(&buf_payload);
+}
+
+static void fn_printf_va_fl(const char *file, int line,
+			    uint64_t us_elapsed_absolute,
+			    const char *fmt, va_list ap)
+{
+	struct strbuf buf_payload = STRBUF_INIT;
+
+	maybe_append_string_va(&buf_payload, fmt, ap);
+	normal_io_write_fl(file, line, &buf_payload);
+	strbuf_release(&buf_payload);
+}
+
+struct tr2_tgt tr2_tgt_normal =
+{
+	&tr2dst_normal,
+
+	fn_init,
+	fn_term,
+
+	fn_version_fl,
+	fn_start_fl,
+	fn_exit_fl,
+	fn_signal,
+	fn_atexit,
+	fn_error_va_fl,
+	fn_command_path_fl,
+	fn_command_verb_fl,
+	fn_command_subverb_fl,
+	fn_alias_fl,
+	fn_child_start_fl,
+	fn_child_exit_fl,
+	NULL, /* thread_start */
+	NULL, /* thread_exit */
+	fn_exec_fl,
+	fn_exec_result_fl,
+	fn_param_fl,
+	fn_repo_fl,
+	NULL, /* region_enter */
+	NULL, /* region_leave */
+	NULL, /* data */
+	NULL, /* data_json */
+	fn_printf_va_fl,
+};
diff --git a/trace2/tr2_tgt_perf.c b/trace2/tr2_tgt_perf.c
new file mode 100644
index 00000000000000..d613bcb2f300de
--- /dev/null
+++ b/trace2/tr2_tgt_perf.c
@@ -0,0 +1,574 @@
+#include "cache.h"
+#include "config.h"
+#include "run-command.h"
+#include "quote.h"
+#include "version.h"
+#include "json-writer.h"
+#include "trace2/tr2_dst.h"
+#include "trace2/tr2_sid.h"
+#include "trace2/tr2_tbuf.h"
+#include "trace2/tr2_tgt.h"
+#include "trace2/tr2_tls.h"
+
+/*
+ * This file contains "private/protected" declarations for TRACE2.
+ */
+
+static struct tr2_dst tr2dst_perf   = { "GIT_TR2_PERF", 0, 0, 0 };
+
+/*
+ * Set this environment variable to true to omit the "<time> <file>:<line>"
+ * fields from each line written to the builtin performance target.
+ *
+ * Unit tests may want to use this to help with testing.
+ */
+#define TR2_ENVVAR_PERF_BARE "GIT_TR2_BARE"
+static int tr2env_perf_bare;
+
+#define TR2FMT_PERF_FL_WIDTH       (50)
+#define TR2FMT_PERF_MAX_EVENT_NAME (12)
+#define TR2FMT_PERF_REPO_WIDTH     (4)
+#define TR2FMT_PERF_CATEGORY_WIDTH (10)
+
+#define TR2_DOTS_BUFFER_SIZE (100)
+#define TR2_INDENT (2)
+#define TR2_INDENT_LENGTH(ctx) (((ctx)->nr_open_regions - 1) * TR2_INDENT)
+
+static struct strbuf dots = STRBUF_INIT;
+
+static int fn_init(void)
+{
+	int want = tr2_dst_trace_want(&tr2dst_perf);
+	int want_bare;
+	char *bare;
+
+	if (!want)
+		return want;
+
+	strbuf_addchars(&dots, '.', TR2_DOTS_BUFFER_SIZE);
+
+	bare = getenv(TR2_ENVVAR_PERF_BARE);
+	if (bare && *bare &&
+	    ((want_bare = git_parse_maybe_bool(bare)) != -1))
+		tr2env_perf_bare = want_bare;
+
+	return want;
+}
+
+static void fn_term(void)
+{
+	tr2_dst_trace_disable(&tr2dst_perf);
+
+	strbuf_release(&dots);
+}
+
+/*
+ * Format trace line prefix in human-readable classic format for
+ * the performance target:
+ *     "[<time> [<file>:<line>] <bar> <nr_parents> <bar>]
+ *         <thread_name> <bar> <event_name> <bar> [<repo>] <bar>
+ *         [<elapsed_absolute>] [<elapsed_relative>] <bar>
+ *         [<category>] <bar> [<dots>] "
+ */
+static void perf_fmt_prepare(
+	const char *event_name, struct tr2tls_thread_ctx *ctx,
+	const char *file, int line, const struct repository *repo,
+	uint64_t *p_us_elapsed_absolute, uint64_t *p_us_elapsed_relative,
+	const char *category, struct strbuf *buf)
+{
+	int len;
+
+	strbuf_setlen(buf,0);
+
+	if (!tr2env_perf_bare) {
+
+		struct tr2_tbuf tb_now;
+
+		tr2_tbuf_local_time(&tb_now);
+		strbuf_addstr(buf, tb_now.buf);
+		strbuf_addch(buf, ' ');
+
+		if (file && *file)
+			strbuf_addf(buf, "%s:%d ", file, line);
+		while (buf->len < TR2FMT_PERF_FL_WIDTH)
+			strbuf_addch(buf, ' ');
+
+		strbuf_addf(buf, "| d%d | ", tr2_sid_depth());
+	}
+
+	strbuf_addf(buf, "%-*s | %-*s | ",
+		    TR2_MAX_THREAD_NAME, ctx->thread_name.buf,
+		    TR2FMT_PERF_MAX_EVENT_NAME, event_name);
+
+	len = buf->len + TR2FMT_PERF_REPO_WIDTH;
+	if (repo)
+		strbuf_addf(buf, "r%d ", repo->trace2_repo_id);
+	while (buf->len < len)
+		strbuf_addch(buf, ' ' );
+	strbuf_addstr(buf, "| ");
+
+	if (p_us_elapsed_absolute)
+		strbuf_addf(buf, "%9.6f | ",
+			    ((double)(*p_us_elapsed_absolute)) / 1000000.0);
+	else
+		strbuf_addf(buf, "%9s | ", " ");
+
+	if (p_us_elapsed_relative)
+		strbuf_addf(buf, "%9.6f | ",
+			    ((double)(*p_us_elapsed_relative)) / 1000000.0);
+	else
+		strbuf_addf(buf, "%9s | ", " ");
+		
+	strbuf_addf(buf, "%-*s | ", TR2FMT_PERF_CATEGORY_WIDTH,
+		    (category ? category : ""));
+
+	if (ctx->nr_open_regions > 0) {
+		int len_indent = TR2_INDENT_LENGTH(ctx);
+		while (len_indent > dots.len) {
+			strbuf_addf(buf, "%s", dots.buf);
+			len_indent -= dots.len;
+		}
+		strbuf_addf(buf, "%.*s", len_indent, dots.buf);
+	}
+}
+
+static void perf_io_write_fl(
+	const char *file, int line,
+	const char *event_name,
+	const struct repository *repo,
+	uint64_t *p_us_elapsed_absolute,
+	uint64_t *p_us_elapsed_relative,
+	const char *category,
+	const struct strbuf *buf_payload)
+{
+	struct tr2tls_thread_ctx *ctx = tr2tls_get_self();
+	struct strbuf buf_line = STRBUF_INIT;
+
+	perf_fmt_prepare(event_name, ctx, file, line, repo,
+			 p_us_elapsed_absolute, p_us_elapsed_relative,
+			 category, &buf_line);
+	strbuf_addbuf(&buf_line, buf_payload);
+	tr2_dst_write_line(&tr2dst_perf, &buf_line);
+	strbuf_release(&buf_line);
+}
+
+static void fn_version_fl(const char *file, int line)
+{
+	const char *event_name = "version";
+	struct strbuf buf_payload = STRBUF_INIT;
+
+	strbuf_addf(&buf_payload, "%s", git_version_string);
+
+	perf_io_write_fl(file, line, event_name, NULL,
+			 NULL, NULL, NULL,
+			 &buf_payload);
+	strbuf_release(&buf_payload);
+}
+
+static void fn_start_fl(const char *file, int line, const char **argv)
+{
+	const char *event_name = "start";
+	struct strbuf buf_payload = STRBUF_INIT;
+
+	sq_quote_argv_pretty(&buf_payload, argv);
+
+	perf_io_write_fl(file, line, event_name, NULL,
+			 NULL, NULL, NULL,
+			 &buf_payload);
+	strbuf_release(&buf_payload);
+}
+
+static void fn_exit_fl(const char *file, int line,
+		       uint64_t us_elapsed_absolute, int code)
+{
+	const char *event_name = "exit";
+	struct strbuf buf_payload = STRBUF_INIT;
+
+	strbuf_addf(&buf_payload, "code:%d", code);
+
+	perf_io_write_fl(file, line, event_name, NULL,
+			 &us_elapsed_absolute, NULL, NULL,
+			 &buf_payload);
+	strbuf_release(&buf_payload);
+}
+
+static void fn_signal(uint64_t us_elapsed_absolute, int signo)
+{
+	const char *event_name = "signal";
+	struct strbuf buf_payload = STRBUF_INIT;
+
+	strbuf_addf(&buf_payload, "signo:%d", signo);
+
+	perf_io_write_fl(__FILE__, __LINE__, event_name, NULL,
+			 &us_elapsed_absolute, NULL, NULL,
+			 &buf_payload);
+	strbuf_release(&buf_payload);
+}
+
+static void fn_atexit(uint64_t us_elapsed_absolute, int code)
+{
+	const char *event_name = "atexit";
+	struct strbuf buf_payload = STRBUF_INIT;
+
+	strbuf_addf(&buf_payload, "code:%d", code);
+
+	perf_io_write_fl(__FILE__, __LINE__, event_name, NULL,
+			 &us_elapsed_absolute, NULL, NULL,
+			 &buf_payload);
+	strbuf_release(&buf_payload);
+}
+
+static void maybe_append_string_va(struct strbuf *buf,
+				   const char *fmt, va_list ap)
+{
+	if (fmt && *fmt && ap) {
+		va_list copy_ap;
+
+		va_copy(copy_ap, ap);
+		strbuf_vaddf(buf, fmt, copy_ap);
+		va_end(copy_ap);
+		return;
+	}
+
+	if (fmt && *fmt) {
+		strbuf_addstr(buf, fmt);
+		return;
+	}
+}
+
+static void fn_error_va_fl(const char *file, int line,
+			   const char *fmt, va_list ap)
+{
+	const char *event_name = "error";
+	struct strbuf buf_payload = STRBUF_INIT;
+
+	maybe_append_string_va(&buf_payload, fmt, ap);
+
+	perf_io_write_fl(file, line, event_name, NULL,
+			 NULL, NULL, NULL,
+			 &buf_payload);
+	strbuf_release(&buf_payload);
+}
+
+static void fn_command_path_fl(const char *file, int line,
+			       const char *pathname)
+{
+	const char *event_name = "cmd_path";
+	struct strbuf buf_payload = STRBUF_INIT;
+
+	strbuf_addstr(&buf_payload, pathname);
+
+	perf_io_write_fl(file, line, event_name, NULL,
+			 NULL, NULL, NULL,
+			 &buf_payload);
+	strbuf_release(&buf_payload);
+}
+
+static void fn_command_verb_fl(const char *file, int line,
+			       const char *command_verb,
+			       const char *verb_hierarchy)
+{
+	const char *event_name = "cmd_verb";
+	struct strbuf buf_payload = STRBUF_INIT;
+
+	strbuf_addstr(&buf_payload, command_verb);
+
+	perf_io_write_fl(file, line, event_name, NULL,
+			 NULL, NULL, NULL,
+			 &buf_payload);
+	strbuf_release(&buf_payload);
+}
+
+static void fn_command_subverb_fl(const char *file, int line,
+			       const char *command_subverb)
+{
+	const char *event_name = "cmd_subverb";
+	struct strbuf buf_payload = STRBUF_INIT;
+
+	strbuf_addstr(&buf_payload, command_subverb);
+
+	perf_io_write_fl(file, line, event_name, NULL,
+			 NULL, NULL, NULL,
+			 &buf_payload);
+	strbuf_release(&buf_payload);
+}
+
+static void fn_alias_fl(const char *file, int line, const char *alias,
+			const char **argv)
+{
+	const char *event_name = "alias";
+	struct strbuf buf_payload = STRBUF_INIT;
+
+	strbuf_addf(&buf_payload, "alias:%s argv:", alias);
+	sq_quote_argv_pretty(&buf_payload, argv);
+
+	perf_io_write_fl(file, line, event_name, NULL,
+			 NULL, NULL, NULL,
+			 &buf_payload);
+	strbuf_release(&buf_payload);
+}
+
+static void fn_child_start_fl(const char *file, int line,
+			      uint64_t us_elapsed_absolute,
+			      const struct child_process *cmd)
+{
+	const char *event_name = "child_start";
+	struct strbuf buf_payload = STRBUF_INIT;
+
+	if (cmd->trace2_hook_name) {
+		strbuf_addf(&buf_payload, "[ch%d] class:hook hook:%s",
+			    cmd->trace2_child_id, cmd->trace2_hook_name);
+	} else {
+		const char *child_class = ((cmd->trace2_child_class) ?
+					   cmd->trace2_child_class : "?");
+		strbuf_addf(&buf_payload, "[ch%d] class:%s",
+			    cmd->trace2_child_id, child_class);
+	}
+
+	if (cmd->dir) {
+		strbuf_addstr(&buf_payload, " cd:");
+		sq_quote_buf_pretty(&buf_payload, cmd->dir);
+	}
+
+	strbuf_addstr(&buf_payload, " argv:");
+	if (cmd->git_cmd)
+		strbuf_addstr(&buf_payload, " git");
+	sq_quote_argv_pretty(&buf_payload, cmd->argv);
+
+	perf_io_write_fl(file, line, event_name, NULL,
+			 &us_elapsed_absolute, NULL, NULL,
+			 &buf_payload);
+	strbuf_release(&buf_payload);
+}
+
+static void fn_child_exit_fl(const char *file, int line,
+			     uint64_t us_elapsed_absolute,
+			     int cid, int pid, int code,
+			     uint64_t us_elapsed_child)
+{
+	const char *event_name = "child_exit";
+	struct strbuf buf_payload = STRBUF_INIT;
+
+	strbuf_addf(&buf_payload, "[ch%d] pid:%d code:%d", cid, pid, code);
+
+	perf_io_write_fl(file, line, event_name, NULL,
+			 &us_elapsed_absolute, &us_elapsed_child, NULL,
+			 &buf_payload);
+	strbuf_release(&buf_payload);
+}
+
+static void fn_thread_start_fl(const char *file, int line,
+				     uint64_t us_elapsed_absolute)
+{
+	const char *event_name = "thread_start";
+	struct strbuf buf_payload = STRBUF_INIT;
+
+	perf_io_write_fl(file, line, event_name, NULL,
+			 &us_elapsed_absolute, NULL, NULL,
+			 &buf_payload);
+	strbuf_release(&buf_payload);
+}
+
+static void fn_thread_exit_fl(const char *file, int line,
+			      uint64_t us_elapsed_absolute,
+			      uint64_t us_elapsed_thread)
+{
+	const char *event_name = "thread_exit";
+	struct strbuf buf_payload = STRBUF_INIT;
+
+	perf_io_write_fl(file, line, event_name, NULL,
+			 &us_elapsed_absolute, &us_elapsed_thread, NULL,
+			 &buf_payload);
+	strbuf_release(&buf_payload);
+}
+
+static void fn_exec_fl(const char *file, int line,
+		       uint64_t us_elapsed_absolute,
+		       int exec_id, const char *exe, const char **argv)
+{
+	const char *event_name = "exec";
+	struct strbuf buf_payload = STRBUF_INIT;
+
+	strbuf_addf(&buf_payload, "id:%d ", exec_id);
+	strbuf_addstr(&buf_payload, "argv:");
+	if (exe)
+		strbuf_addf(&buf_payload, " %s", exe);
+	sq_quote_argv_pretty(&buf_payload, argv);
+
+	perf_io_write_fl(file, line, event_name, NULL,
+			 &us_elapsed_absolute, NULL, NULL,
+			 &buf_payload);
+	strbuf_release(&buf_payload);
+}
+
+static void fn_exec_result_fl(const char *file, int line,
+			      uint64_t us_elapsed_absolute,
+			      int exec_id, int code)
+{
+	const char *event_name = "exec_result";
+	struct strbuf buf_payload = STRBUF_INIT;
+
+	strbuf_addf(&buf_payload, "id:%d code:%d", exec_id, code);
+	if (code > 0)
+		strbuf_addf(&buf_payload, " err:%s", strerror(code));
+
+	perf_io_write_fl(file, line, event_name, NULL,
+			 &us_elapsed_absolute, NULL, NULL,
+			 &buf_payload);
+	strbuf_release(&buf_payload);
+}
+
+static void fn_param_fl(const char *file, int line,
+			const char *param, const char *value)
+{
+	const char *event_name = "def_param";
+	struct strbuf buf_payload = STRBUF_INIT;
+
+	strbuf_addf(&buf_payload, "%s:%s", param, value);
+
+	perf_io_write_fl(file, line, event_name, NULL,
+			 NULL, NULL, NULL,
+			 &buf_payload);
+	strbuf_release(&buf_payload);
+}
+
+static void fn_repo_fl(const char *file, int line,
+		       const struct repository *repo)
+{
+	const char *event_name = "def_repo";
+	struct strbuf buf_payload = STRBUF_INIT;
+
+	strbuf_addstr(&buf_payload, "worktree:");
+	sq_quote_buf_pretty(&buf_payload, repo->worktree);
+
+	perf_io_write_fl(file, line, event_name, repo,
+			 NULL, NULL, NULL,
+			 &buf_payload);
+	strbuf_release(&buf_payload);
+}
+
+static void fn_region_enter_printf_va_fl(const char *file, int line,
+					 uint64_t us_elapsed_absolute,
+					 const char *category,
+					 const char *label,
+					 const struct repository *repo,
+					 const char *fmt, va_list ap)
+{
+	const char *event_name = "region_enter";
+	struct strbuf buf_payload = STRBUF_INIT;
+
+	if (label)
+		strbuf_addf(&buf_payload, "label:%s ", label);
+	maybe_append_string_va(&buf_payload, fmt, ap);
+
+	perf_io_write_fl(file, line, event_name, repo,
+			 &us_elapsed_absolute, NULL, category,
+			 &buf_payload);
+	strbuf_release(&buf_payload);
+}
+
+static void fn_region_leave_printf_va_fl(const char *file, int line,
+					 uint64_t us_elapsed_absolute,
+					 uint64_t us_elapsed_region,
+					 const char *category,
+					 const char *label,
+					 const struct repository *repo,
+					 const char *fmt, va_list ap)
+{
+	const char *event_name = "region_leave";
+	struct strbuf buf_payload = STRBUF_INIT;
+
+	if (label)
+		strbuf_addf(&buf_payload, "label:%s ", label);
+	maybe_append_string_va(&buf_payload, fmt, ap);
+
+	perf_io_write_fl(file, line, event_name, repo,
+			 &us_elapsed_absolute, &us_elapsed_region, category,
+			 &buf_payload);
+	strbuf_release(&buf_payload);
+}
+
+static void fn_data_fl(const char *file, int line,
+		       uint64_t us_elapsed_absolute,
+		       uint64_t us_elapsed_region,
+		       const char *category,
+		       const struct repository *repo,
+		       const char *key,
+		       const char *value)
+{
+	const char *event_name = "data";
+	struct strbuf buf_payload = STRBUF_INIT;
+
+	strbuf_addf(&buf_payload, "%s:%s", key, value);
+
+	perf_io_write_fl(file, line, event_name, repo,
+			 &us_elapsed_absolute, &us_elapsed_region, category,
+			 &buf_payload);
+	strbuf_release(&buf_payload);
+}
+
+static void fn_data_json_fl(const char *file, int line,
+			    uint64_t us_elapsed_absolute,
+			    uint64_t us_elapsed_region,
+			    const char *category,
+			    const struct repository *repo,
+			    const char *key,
+			    const struct json_writer *value)
+{
+	const char *event_name = "data_json";
+	struct strbuf buf_payload = STRBUF_INIT;
+
+	strbuf_addf(&buf_payload, "%s:%s", key, value->json.buf);
+
+	perf_io_write_fl(file, line, event_name, repo,
+			 &us_elapsed_absolute, &us_elapsed_region, category,
+			 &buf_payload);
+	strbuf_release(&buf_payload);
+}
+
+static void fn_printf_va_fl(const char *file, int line,
+			    uint64_t us_elapsed_absolute,
+			    const char *fmt, va_list ap)
+{
+	const char *event_name = "printf";
+	struct strbuf buf_payload = STRBUF_INIT;
+
+	maybe_append_string_va(&buf_payload, fmt, ap);
+
+	perf_io_write_fl(file, line, event_name, NULL,
+			 &us_elapsed_absolute, NULL, NULL,
+			 &buf_payload);
+	strbuf_release(&buf_payload);
+}
+
+struct tr2_tgt tr2_tgt_perf =
+{
+	&tr2dst_perf,
+
+	fn_init,
+	fn_term,
+
+	fn_version_fl,
+	fn_start_fl,
+	fn_exit_fl,
+	fn_signal,
+	fn_atexit,
+	fn_error_va_fl,
+	fn_command_path_fl,
+	fn_command_verb_fl,
+	fn_command_subverb_fl,
+	fn_alias_fl,
+	fn_child_start_fl,
+	fn_child_exit_fl,
+	fn_thread_start_fl,
+	fn_thread_exit_fl,
+	fn_exec_fl,
+	fn_exec_result_fl,
+	fn_param_fl,
+	fn_repo_fl,
+	fn_region_enter_printf_va_fl,
+	fn_region_leave_printf_va_fl,
+	fn_data_fl,
+	fn_data_json_fl,
+	fn_printf_va_fl,
+};
diff --git a/trace2/tr2_tls.c b/trace2/tr2_tls.c
new file mode 100644
index 00000000000000..4d5747951e5e43
--- /dev/null
+++ b/trace2/tr2_tls.c
@@ -0,0 +1,170 @@
+#include "cache.h"
+#include "thread-utils.h"
+#include "trace2/tr2_tls.h"
+
+/*
+ * This file contains "private/protected" routines for TRACE2.
+ */
+
+/*
+ * Initialize size of the thread stack for nested regions.
+ * This is used to store nested region start times.  Note that
+ * this stack is per-thread and not per-trace-key.
+ */
+#define TR2_REGION_NESTING_INITIAL_SIZE (100)
+
+static struct tr2tls_thread_ctx *tr2tls_thread_main;
+static uint64_t tr2tls_us_start_main;
+
+static pthread_mutex_t tr2tls_mutex;
+static pthread_key_t tr2tls_key;
+
+static int tr2_next_thread_id; /* modify under lock */
+
+struct tr2tls_thread_ctx *tr2tls_create_self(const char *thread_name)
+{
+	uint64_t us_now = getnanotime() / 1000;
+	struct tr2tls_thread_ctx *ctx = xcalloc(1, sizeof(*ctx));
+
+	/*
+	 * Implicitly "tr2tls_push_self()" to capture the thread's start
+	 * time in array_us_start[0].  For the main thread this gives us the
+	 * application run time.
+	 */
+	ctx->alloc = TR2_REGION_NESTING_INITIAL_SIZE;
+	ctx->array_us_start = (uint64_t*)xcalloc(ctx->alloc, sizeof(uint64_t));
+	ctx->array_us_start[ctx->nr_open_regions++] = us_now;
+
+	ctx->thread_id = tr2tls_locked_increment(&tr2_next_thread_id);
+	
+	strbuf_init(&ctx->thread_name, 0);
+	if (ctx->thread_id)
+		strbuf_addf(&ctx->thread_name, "th%02d:", ctx->thread_id);
+	strbuf_addstr(&ctx->thread_name, thread_name);
+	if (ctx->thread_name.len > TR2_MAX_THREAD_NAME)
+		strbuf_setlen(&ctx->thread_name, TR2_MAX_THREAD_NAME);
+
+	pthread_setspecific(tr2tls_key, ctx);
+
+	return ctx;
+}
+
+struct tr2tls_thread_ctx *tr2tls_get_self(void)
+{
+	struct tr2tls_thread_ctx * ctx = pthread_getspecific(tr2tls_key);
+
+	/*
+	 * If the thread-proc did not call trace2_thread_start(), we won't
+	 * have any TLS data associated with the current thread.  Fix it
+	 * here and silently continue.
+	 */
+	if (!ctx)
+		ctx = tr2tls_create_self("unknown");
+
+	return ctx;
+}
+
+int tr2tls_is_main_thread(void)
+{
+	struct tr2tls_thread_ctx * ctx;
+
+	ctx = tr2tls_get_self();
+
+	return ctx == tr2tls_thread_main;
+}
+
+void tr2tls_unset_self(void)
+{
+	struct tr2tls_thread_ctx * ctx;
+
+	ctx = tr2tls_get_self();
+
+	pthread_setspecific(tr2tls_key, NULL);
+
+	free(ctx->array_us_start);
+	free(ctx);
+}
+
+void tr2tls_push_self(uint64_t us_now)
+{
+	struct tr2tls_thread_ctx *ctx = tr2tls_get_self();
+
+	ALLOC_GROW(ctx->array_us_start, ctx->nr_open_regions + 1, ctx->alloc);
+	ctx->array_us_start[ctx->nr_open_regions++] = us_now;
+}
+
+void tr2tls_pop_self(void)
+{
+	struct tr2tls_thread_ctx *ctx = tr2tls_get_self();
+
+	if (!ctx->nr_open_regions)
+		BUG("no open regions in thread '%s'", ctx->thread_name.buf);
+
+	ctx->nr_open_regions--;
+}
+
+void tr2tls_pop_unwind_self(void)
+{
+	struct tr2tls_thread_ctx *ctx = tr2tls_get_self();
+
+	while (ctx->nr_open_regions > 1)
+		tr2tls_pop_self();
+}
+
+uint64_t tr2tls_region_elasped_self(uint64_t us)
+{
+	struct tr2tls_thread_ctx *ctx;
+	uint64_t us_start;
+
+	ctx = tr2tls_get_self();
+	if (!ctx->nr_open_regions)
+		return 0;
+	
+	us_start = ctx->array_us_start[ctx->nr_open_regions - 1];
+
+	return us - us_start;
+}
+
+uint64_t tr2tls_absolute_elapsed(uint64_t us)
+{
+	if (!tr2tls_thread_main)
+		return 0;
+
+	return us - tr2tls_us_start_main;
+}
+
+void tr2tls_init(void)
+{
+	pthread_key_create(&tr2tls_key, NULL);
+	init_recursive_mutex(&tr2tls_mutex);
+
+	tr2tls_thread_main = tr2tls_create_self("main");
+	/*
+	 * Keep a copy of the absolute start time of the main thread
+	 * in a fixed variable since other threads need to access it.
+	 * This also eliminates the need to lock accesses to the main
+	 * thread's array (because of reallocs).
+	 */
+	tr2tls_us_start_main = tr2tls_thread_main->array_us_start[0];
+}
+
+void tr2tls_release(void)
+{
+	tr2tls_unset_self();
+	tr2tls_thread_main = NULL;
+
+	pthread_mutex_destroy(&tr2tls_mutex);
+	pthread_key_delete(tr2tls_key);
+}
+
+int tr2tls_locked_increment(int *p)
+{
+	int current_value;
+
+	pthread_mutex_lock(&tr2tls_mutex);
+	current_value = *p;
+	*p = current_value + 1;
+	pthread_mutex_unlock(&tr2tls_mutex);
+
+	return current_value;
+}
diff --git a/trace2/tr2_tls.h b/trace2/tr2_tls.h
new file mode 100644
index 00000000000000..145fa7e462ed77
--- /dev/null
+++ b/trace2/tr2_tls.h
@@ -0,0 +1,99 @@
+#ifndef TR2_TLS_H
+#define TR2_TLS_H
+
+/*
+ * This file contains "private/protected" declarations for TRACE2.
+ */
+
+/*
+ * Arbitry limit for thread names for column alignment.
+ */
+#define TR2_MAX_THREAD_NAME (24)
+
+struct tr2tls_thread_ctx {
+	struct strbuf thread_name;
+	uint64_t *array_us_start;
+	int alloc;
+	int nr_open_regions; /* plays role of "nr" in ALLOC_GROW */
+	int thread_id;
+};
+
+/*
+ * Create TLS data for the current thread.  This gives us a place to
+ * put per-thread data, such as thread start time, function nesting
+ * and a per-thread label for our messages.
+ *
+ * We assume the first thread is "main".  Other threads are given
+ * non-zero thread-ids to help distinguish messages from concurrent
+ * threads.
+ *
+ * Truncate the thread name if necessary to help with column alignment
+ * in printf-style messages.
+ *
+ * In this and all following functions the term "self" refers to the
+ * current thread.
+ */
+struct tr2tls_thread_ctx *tr2tls_create_self(const char *thread_name);
+
+/*
+ * Get our TLS data.
+ */
+struct tr2tls_thread_ctx *tr2tls_get_self(void);
+
+/*
+ * return true if the current thread is the main thread.
+ */
+int tr2tls_is_main_thread(void);
+
+/*
+ * Free our TLS data.
+ */
+void tr2tls_unset_self(void);
+
+/*
+ * Begin a new nested region and remember the start time.
+ */
+void tr2tls_push_self(uint64_t us_now);
+
+/*
+ * End the innermost nested region.
+ */
+void tr2tls_pop_self(void);
+
+/*
+ * Pop any extra (above the first) open regions on the current
+ * thread and discard.  During a thread-exit, we should only
+ * have region[0] that was pushed in trace2_thread_start() if
+ * the thread exits normally.
+ */
+void tr2tls_pop_unwind_self(void);
+
+/*
+ * Compute the elapsed time since the innermost region in the
+ * current thread started and the given time (usually now).
+ */
+uint64_t tr2tls_region_elasped_self(uint64_t us);
+
+/*
+ * Compute the elapsed time since the main thread started
+ * and the given time (usually now).  This is assumed to
+ * be the absolute run time of the process.
+ */
+uint64_t tr2tls_absolute_elapsed(uint64_t us);
+
+/*
+ * Initialize the tr2 TLS system.
+ */
+void tr2tls_init(void);
+
+/*
+ * Free all tr2 TLS resources.
+ */
+void tr2tls_release(void);
+
+/*
+ * Protected increment of an integer.
+ */
+int tr2tls_locked_increment(int *p);
+
+#endif /* TR2_TLS_H */
diff --git a/trace2/tr2_verb.c b/trace2/tr2_verb.c
new file mode 100644
index 00000000000000..674e3b973bcff6
--- /dev/null
+++ b/trace2/tr2_verb.c
@@ -0,0 +1,34 @@
+#include "cache.h"
+#include "trace2/tr2_verb.h"
+
+/*
+ * This file contains "private/protected" routines for TRACE2.
+ */
+
+#define TR2_ENVVAR_PARENT_VERB "GIT_TR2_PARENT_VERB"
+
+static struct strbuf tr2verb_hierarchy = STRBUF_INIT;
+
+void tr2_verb_append_hierarchy(const char *verb)
+{
+	const char *parent_verb = getenv(TR2_ENVVAR_PARENT_VERB);
+
+	strbuf_reset(&tr2verb_hierarchy);
+	if (parent_verb && *parent_verb) {
+		strbuf_addstr(&tr2verb_hierarchy, parent_verb);
+		strbuf_addch(&tr2verb_hierarchy, '/');
+	}
+	strbuf_addstr(&tr2verb_hierarchy, verb);
+
+	setenv(TR2_ENVVAR_PARENT_VERB, tr2verb_hierarchy.buf, 1);
+}
+
+const char *tr2_verb_get_hierarchy(void)
+{
+	return tr2verb_hierarchy.buf;
+}
+
+void tr2_verb_release(void)
+{
+	strbuf_release(&tr2verb_hierarchy);
+}
diff --git a/trace2/tr2_verb.h b/trace2/tr2_verb.h
new file mode 100644
index 00000000000000..44f11e02e7b1c8
--- /dev/null
+++ b/trace2/tr2_verb.h
@@ -0,0 +1,28 @@
+#ifndef TR2_VERB_H
+#define TR2_VERB_H
+
+/*
+ * This file contains "private/protected" routines for TRACE2.
+ */
+
+/*
+ * Append the current git command's "verb" to the list being maintained
+ * in the environment.
+ *
+ * The hierarchy for a top-level git command is just the current verb.
+ * For a child git process, the hierarchy lists the verbs of the parent
+ * git processes (much like the SID).
+ *
+ * The hierarchy for the current process will be exported to the environment
+ * and inherited by child processes.
+ */
+void tr2_verb_append_hierarchy(const char *verb);
+
+/*
+ * Get the verb hierarchy for the current process.
+ */
+const char *tr2_verb_get_hierarchy(void);
+
+void tr2_verb_release(void);
+
+#endif /* TR2_VERB_H */
diff --git a/usage.c b/usage.c
index cc803336bd5e67..3f57bac0d52387 100644
--- a/usage.c
+++ b/usage.c
@@ -22,17 +22,48 @@ void vreportf(const char *prefix, const char *err, va_list params)
 static NORETURN void usage_builtin(const char *err, va_list params)
 {
 	vreportf("usage: ", err, params);
+
+	/*
+	 * For command instances where we detected a syntax *before* the
+	 * command dispatch in cmd_main(), we don't know what verb to
+	 * report.  Force it to "_usage_" to facilitate post-processing.
+	 */
+	trace2_cmd_verb("_usage_");
+
+	/*
+	 * Currently, the (err, params) are usually just the static usage
+	 * string which isn't very useful here.  Usually, the call site
+	 * manually calls fprintf(stderr,...) with the actual detailed
+	 * syntax error before calling usage().
+	 *
+	 * TODO It would be nice to update the call sites to pass both
+	 * the static usage string and the detailed error message.
+	 */
+
 	exit(129);
 }
 
 static NORETURN void die_builtin(const char *err, va_list params)
 {
+	/*
+	 * We call this trace2 function first and expect it to va_copy 'params'
+	 * before using it (because an 'ap' can only be walked once).
+	 */
+	trace2_cmd_error_va(err, params);
+
 	vreportf("fatal: ", err, params);
+
 	exit(128);
 }
 
 static void error_builtin(const char *err, va_list params)
 {
+	/*
+	 * We call this trace2 function first and expect it to va_copy 'params'
+	 * before using it (because an 'ap' can only be walked once).
+	 */
+	trace2_cmd_error_va(err, params);
+
 	vreportf("error: ", err, params);
 }
 

From 3adeefcbaffe1a2cd99d38e716ea0b5d3a85046c Mon Sep 17 00:00:00 2001
From: Jeff Hostetler <jeffhost@microsoft.com>
Date: Mon, 12 Nov 2018 13:54:16 -0500
Subject: [PATCH 10/25] trace2: collect platform-specific process information

Add optional platform-specific code to log information about
the current process.

On Windows, this includes whether git.exe is running under a
debugger and information about the ancestors of the process.

The purpose of this information is to help indicate if the
process was launched interactively or in the background by
an IDE, for example.

Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
---
 common-main.c           |   1 +
 compat/win32/ancestry.c | 102 ++++++++++++++++++++++++++++++++++++++++
 config.mak.uname        |   6 ++-
 trace2.h                |  13 +++++
 4 files changed, 120 insertions(+), 2 deletions(-)
 create mode 100644 compat/win32/ancestry.c

diff --git a/common-main.c b/common-main.c
index 6dbdc4adf272ef..d484aec20979ac 100644
--- a/common-main.c
+++ b/common-main.c
@@ -37,6 +37,7 @@ int main(int argc, const char **argv)
 
 	trace2_initialize();
 	trace2_cmd_start(argv);
+	trace2_collect_process_info();
 
 	git_resolve_executable_dir(argv[0]);
 
diff --git a/compat/win32/ancestry.c b/compat/win32/ancestry.c
new file mode 100644
index 00000000000000..7ed3cc66618c95
--- /dev/null
+++ b/compat/win32/ancestry.c
@@ -0,0 +1,102 @@
+#include "../../cache.h"
+#include "../../json-writer.h"
+#include <Psapi.h>
+#include <tlHelp32.h>
+
+/*
+ * Find the process data for the given PID in the given snapshot
+ * and update the PROCESSENTRY32 data.
+ */
+static int find_pid(DWORD pid, HANDLE hSnapshot, PROCESSENTRY32 *pe32)
+{
+	pe32->dwSize = sizeof(PROCESSENTRY32);
+
+	if (Process32First(hSnapshot, pe32)) {
+		do {
+			if (pe32->th32ProcessID == pid)
+				return 1;
+		} while (Process32Next(hSnapshot, pe32));
+	}
+	return 0;
+}
+
+/*
+ * Accumulate JSON array:
+ *     [
+ *         exe-name-parent,
+ *         exe-name-grand-parent,
+ *         ...
+ *     ]
+ *
+ * Note: we only report the filename of the process executable; the
+ *       only way to get its full pathname is to use OpenProcess()
+ *       and GetModuleFileNameEx() or QueryfullProcessImageName()
+ *       and that seems rather expensive (on top of the cost of
+ *       getting the snapshot).
+ */
+static void get_processes(struct json_writer *jw, HANDLE hSnapshot)
+{
+	PROCESSENTRY32 pe32;
+	DWORD pid;
+
+	pid = GetCurrentProcessId();
+
+	/* We only want parent processes, so skip self. */
+	if (!find_pid(pid, hSnapshot, &pe32))
+		return;
+	pid = pe32.th32ParentProcessID;
+
+	while (find_pid(pid, hSnapshot, &pe32)) {
+
+		jw_array_string(jw, pe32.szExeFile);
+
+		pid = pe32.th32ParentProcessID;
+	}
+}
+
+/*
+ * Emit JSON data for the current and parent processes.  Individual
+ * trace2 targets can decide how to actually print it.
+ */
+static void get_ancestry(void)
+{
+	HANDLE hSnapshot = CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, 0);
+
+	if (hSnapshot != INVALID_HANDLE_VALUE) {
+		struct json_writer jw = JSON_WRITER_INIT;
+
+		jw_array_begin(&jw, 0);
+		get_processes(&jw, hSnapshot);
+		jw_end(&jw);
+
+		trace2_data_json("process", the_repository,
+				 "windows/ancestry", &jw);
+
+		jw_release(&jw);
+		CloseHandle(hSnapshot);
+	}
+}
+
+/*
+ * Is a debugger attached to the current process?
+ *
+ * This will catch debug runs (where the debugger started the process).
+ * This is the normal case.  Since this code is called during our startup,
+ * it will not report instances where a debugger is attached dynamically
+ * to a running git process, but that is relatively rare.
+ */
+static void get_is_being_debugged(void)
+{
+	if (IsDebuggerPresent())
+		trace2_data_intmax("process", the_repository,
+			   "windows/debugger_present", 1);
+}
+
+void trace2_collect_process_info(void)
+{
+	if (!trace2_is_enabled())
+		return;
+
+	get_is_being_debugged();
+	get_ancestry();
+}
diff --git a/config.mak.uname b/config.mak.uname
index c329b2d1204095..7d8289a261f7e4 100644
--- a/config.mak.uname
+++ b/config.mak.uname
@@ -424,7 +424,8 @@ ifeq ($(uname_S),Windows)
 	BASIC_CFLAGS = -nologo -I. -Icompat/vcbuild/include -DWIN32 -D_CONSOLE -DHAVE_STRING_H -D_CRT_SECURE_NO_WARNINGS -D_CRT_NONSTDC_NO_DEPRECATE
 	COMPAT_OBJS = compat/msvc.o compat/winansi.o \
 		compat/win32/pthread.o compat/win32/syslog.o \
-		compat/win32/dirent.o compat/win32/fscache.o
+		compat/win32/dirent.o compat/win32/fscache.o \
+		compat/win32/ancestry.o
 	COMPAT_CFLAGS = -D__USE_MINGW_ACCESS -DDETECT_MSYS_TTY -DNOGDI -DHAVE_STRING_H -Icompat -Icompat/regex -Icompat/win32 -DSTRIP_EXTENSION=\".exe\"
 	BASIC_LDFLAGS = -IGNORE:4217 -IGNORE:4049 -NOLOGO -ENTRY:wmainCRTStartup -SUBSYSTEM:CONSOLE
 	# invalidcontinue.obj allows Git's source code to close the same file
@@ -586,7 +587,8 @@ ifneq (,$(findstring MINGW,$(uname_S)))
 	COMPAT_CFLAGS += -DSTRIP_EXTENSION=\".exe\"
 	COMPAT_OBJS += compat/mingw.o compat/winansi.o \
 		compat/win32/pthread.o compat/win32/syslog.o \
-		compat/win32/dirent.o compat/win32/fscache.o
+		compat/win32/dirent.o compat/win32/fscache.o \
+		compat/win32/ancestry.o
 	BASIC_CFLAGS += -DWIN32 -DPROTECT_NTFS_DEFAULT=1
 	EXTLIBS += -lws2_32
 	GITLIBS += git.res
diff --git a/trace2.h b/trace2.h
index ce89d040b91a50..1909d9d60394c9 100644
--- a/trace2.h
+++ b/trace2.h
@@ -387,4 +387,17 @@ __attribute__((format (printf, 1, 2)))
 void trace2_printf(const char *fmt, ...);
 #endif
 
+/*
+ * Optional platform-specific code to dump information about the
+ * current and any parent process(es).  This is intended to allow
+ * post-processors to know who spawned this git instance and anything
+ * else the platform may be able to tell us about the current process.
+ */
+#if defined(GIT_WINDOWS_NATIVE)
+void trace2_collect_process_info(void);
+#else
+#define trace2_collect_process_info() \
+	do {} while (0)
+#endif
+
 #endif /* TRACE2_H */

From ef2f9278982ebe5fb1ee40641f3b39f3cf11c138 Mon Sep 17 00:00:00 2001
From: Jeff Hostetler <jeffhost@microsoft.com>
Date: Thu, 30 Aug 2018 14:43:15 -0400
Subject: [PATCH 11/25] trace2:data: add trace2 regions to wt-status

Add trace2_region_enter() and trace2_region_leave() calls around the
various phases of a status scan.  This gives elapsed time for each
phase in the GIT_TR2_PERF and GIT_TR2_EVENT trace target.

Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
---
 wt-status.c | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

diff --git a/wt-status.c b/wt-status.c
index 955cfa6c638ca7..682186ed76b47a 100644
--- a/wt-status.c
+++ b/wt-status.c
@@ -749,16 +749,29 @@ static int has_unmerged(struct wt_status *s)
 
 void wt_status_collect(struct wt_status *s)
 {
+	trace2_region_enter("status", "worktrees", the_repository);
 	wt_status_collect_changes_worktree(s);
-	if (s->is_initial)
+	trace2_region_leave("status", "worktrees", the_repository);
+
+	if (s->is_initial) {
+		trace2_region_enter("status", "initial", the_repository);
 		wt_status_collect_changes_initial(s);
-	else
+		trace2_region_leave("status", "initial", the_repository);
+	} else {
+		trace2_region_enter("status", "index", the_repository);
 		wt_status_collect_changes_index(s);
+		trace2_region_leave("status", "index", the_repository);
+	}
+
+	trace2_region_enter("status", "untracked", the_repository);
 	wt_status_collect_untracked(s);
+	trace2_region_leave("status", "untracked", the_repository);
 
+	trace2_region_enter("status", "committable", the_repository);
 	wt_status_get_state(&s->state, s->branch && !strcmp(s->branch, "HEAD"));
 	if (s->state.merge_in_progress && !has_unmerged(s))
 		s->committable = 1;
+	trace2_region_leave("status", "committable", the_repository);
 }
 
 void wt_status_collect_free_buffers(struct wt_status *s)

From 0b2eb6888a8713b30933728f0a00602bfaa14656 Mon Sep 17 00:00:00 2001
From: Jeff Hostetler <jeffhost@microsoft.com>
Date: Fri, 21 Dec 2018 13:24:25 -0500
Subject: [PATCH 12/25] trace2:data: add editor/pager child classification

Add trace2 process classification for editor and pager
child processes.

Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
---
 editor.c | 1 +
 pager.c  | 1 +
 2 files changed, 2 insertions(+)

diff --git a/editor.c b/editor.c
index c985eee1f9d1c7..71547674ab4e88 100644
--- a/editor.c
+++ b/editor.c
@@ -78,6 +78,7 @@ static int launch_specified_editor(const char *editor, const char *path,
 		p.argv = args;
 		p.env = env;
 		p.use_shell = 1;
+		p.trace2_child_class = "editor";
 		if (start_command(&p) < 0)
 			return error("unable to start editor '%s'", editor);
 
diff --git a/pager.c b/pager.c
index bdc75d0b4fad5b..1c82a868ee0a7d 100644
--- a/pager.c
+++ b/pager.c
@@ -103,6 +103,7 @@ void prepare_pager_args(struct child_process *pager_process, const char *pager)
 	argv_array_push(&pager_process->args, pager);
 	pager_process->use_shell = 1;
 	setup_pager_env(&pager_process->env_array);
+	pager_process->trace2_child_class = "pager";
 }
 
 void setup_pager(void)

From a1ab0771a6afda49f9919713aa764c73eb63ccd3 Mon Sep 17 00:00:00 2001
From: Jeff Hostetler <jeffhost@microsoft.com>
Date: Fri, 21 Dec 2018 13:26:31 -0500
Subject: [PATCH 13/25] trace2:data: add trace2 sub-process classification

Add trace2 classification for long-running processes
started in sub-process.c

Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
---
 sub-process.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/sub-process.c b/sub-process.c
index 8d2a1707cfe1a7..3f4af935557c5e 100644
--- a/sub-process.c
+++ b/sub-process.c
@@ -88,6 +88,7 @@ int subprocess_start(struct hashmap *hashmap, struct subprocess_entry *entry, co
 	process->out = -1;
 	process->clean_on_exit = 1;
 	process->clean_on_exit_handler = subprocess_exit_handler;
+	process->trace2_child_class = "subprocess";
 
 	err = start_command(process);
 	if (err) {

From cba8ef2abd0152cb78dbf01a8d6cb85207eac400 Mon Sep 17 00:00:00 2001
From: Jeff Hostetler <jeffhost@microsoft.com>
Date: Wed, 10 Oct 2018 16:00:11 -0400
Subject: [PATCH 14/25] trace2:data: add trace2 transport child classification

Add trace2 child classification for transport processes.

Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
---
 connect.c          | 3 +++
 transport-helper.c | 2 ++
 2 files changed, 5 insertions(+)

diff --git a/connect.c b/connect.c
index d72772a36d01ff..75202e81a23157 100644
--- a/connect.c
+++ b/connect.c
@@ -1255,6 +1255,7 @@ struct child_process *git_connect(int fd[2], const char *url,
 		conn = NULL;
 	} else if (protocol == PROTO_GIT) {
 		conn = git_connect_git(fd, hostandport, path, prog, version, flags);
+		conn->trace2_child_class = "transport/git";
 	} else {
 		struct strbuf cmd = STRBUF_INIT;
 		const char *const *var;
@@ -1297,9 +1298,11 @@ struct child_process *git_connect(int fd[2], const char *url,
 				strbuf_release(&cmd);
 				return NULL;
 			}
+			conn->trace2_child_class = "transport/ssh";
 			fill_ssh_args(conn, ssh_host, port, version, flags);
 		} else {
 			transport_check_allowed("file");
+			conn->trace2_child_class = "transport/file";
 			if (version > 0) {
 				argv_array_pushf(&conn->env_array, GIT_PROTOCOL_ENVIRONMENT "=version=%d",
 						 version);
diff --git a/transport-helper.c b/transport-helper.c
index 35199e50a03e95..fa78a8788568ab 100644
--- a/transport-helper.c
+++ b/transport-helper.c
@@ -129,6 +129,8 @@ static struct child_process *get_helper(struct transport *transport)
 		argv_array_pushf(&helper->env_array, "%s=%s",
 				 GIT_DIR_ENVIRONMENT, get_git_dir());
 
+	helper->trace2_child_class = helper->args.argv[0]; /* "remote-<name>" */
+
 	code = start_command(helper);
 	if (code < 0 && errno == ENOENT)
 		die(_("unable to find remote helper for '%s'"), data->name);

From 9afaef252cf5838ac356d7961a23ec65dbd63116 Mon Sep 17 00:00:00 2001
From: Jeff Hostetler <jeffhost@microsoft.com>
Date: Fri, 21 Dec 2018 14:18:00 -0500
Subject: [PATCH 15/25] trace2:data: add trace2 hook classification

Classify certain child processes as hooks.

Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
---
 builtin/am.c           | 1 +
 builtin/receive-pack.c | 4 ++++
 builtin/worktree.c     | 1 +
 sequencer.c            | 2 ++
 transport.c            | 1 +
 5 files changed, 9 insertions(+)

diff --git a/builtin/am.c b/builtin/am.c
index 8f27f3375b1e92..0c4cb2495cf5f6 100644
--- a/builtin/am.c
+++ b/builtin/am.c
@@ -468,6 +468,7 @@ static int run_post_rewrite_hook(const struct am_state *state)
 
 	cp.in = xopen(am_path(state, "rewritten"), O_RDONLY);
 	cp.stdout_to_stderr = 1;
+	cp.trace2_hook_name = "post-rewrite";
 
 	ret = run_command(&cp);
 
diff --git a/builtin/receive-pack.c b/builtin/receive-pack.c
index 33187bd8e90252..6eef8575b96a2b 100644
--- a/builtin/receive-pack.c
+++ b/builtin/receive-pack.c
@@ -694,6 +694,8 @@ static int run_and_feed_hook(const char *hook_name, feed_fn feed,
 	proc.argv = argv;
 	proc.in = -1;
 	proc.stdout_to_stderr = 1;
+	proc.trace2_hook_name = hook_name;
+
 	if (feed_state->push_options) {
 		int i;
 		for (i = 0; i < feed_state->push_options->nr; i++)
@@ -807,6 +809,7 @@ static int run_update_hook(struct command *cmd)
 	proc.stdout_to_stderr = 1;
 	proc.err = use_sideband ? -1 : 0;
 	proc.argv = argv;
+	proc.trace2_hook_name = "update";
 
 	code = start_command(&proc);
 	if (code)
@@ -1190,6 +1193,7 @@ static void run_update_post_hook(struct command *commands)
 	proc.no_stdin = 1;
 	proc.stdout_to_stderr = 1;
 	proc.err = use_sideband ? -1 : 0;
+	proc.trace2_hook_name = "post-update";
 
 	if (!start_command(&proc)) {
 		if (use_sideband)
diff --git a/builtin/worktree.c b/builtin/worktree.c
index 5e8402617727f9..32e6f1b3418f65 100644
--- a/builtin/worktree.c
+++ b/builtin/worktree.c
@@ -401,6 +401,7 @@ static int add_worktree(const char *path, const char *refname,
 			cp.dir = path;
 			cp.env = env;
 			cp.argv = NULL;
+			cp.trace2_hook_name = "post-checkout";
 			argv_array_pushl(&cp.args, absolute_path(hook),
 					 oid_to_hex(&null_oid),
 					 oid_to_hex(&commit->object.oid),
diff --git a/sequencer.c b/sequencer.c
index e3883a0ed8b0bf..4eaa265cc4161c 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -1093,6 +1093,7 @@ static int run_rewrite_hook(const struct object_id *oldoid,
 	proc.argv = argv;
 	proc.in = -1;
 	proc.stdout_to_stderr = 1;
+	proc.trace2_hook_name = "post-rewrite";
 
 	code = start_command(&proc);
 	if (code)
@@ -3730,6 +3731,7 @@ static int pick_commits(struct todo_list *todo_list, struct replay_opts *opts)
 				hook.in = open(rebase_path_rewritten_list(),
 					O_RDONLY);
 				hook.stdout_to_stderr = 1;
+				hook.trace2_hook_name = "post-rewrite";
 				argv_array_push(&hook.args, post_rewrite_hook);
 				argv_array_push(&hook.args, "rebase");
 				/* we don't care if this hook failed */
diff --git a/transport.c b/transport.c
index 5a74b609ffad51..2bf1c367e3f325 100644
--- a/transport.c
+++ b/transport.c
@@ -1061,6 +1061,7 @@ static int run_pre_push_hook(struct transport *transport,
 
 	proc.argv = argv;
 	proc.in = -1;
+	proc.trace2_hook_name = "pre-push";
 
 	if (start_command(&proc)) {
 		finish_command(&proc);

From 517c6d8e27afe1f5d28cecea4535752dbf6f0584 Mon Sep 17 00:00:00 2001
From: Jeff Hostetler <jeffhost@microsoft.com>
Date: Thu, 30 Aug 2018 14:57:26 -0400
Subject: [PATCH 16/25] trace2:data: add trace2 instrumentation to index
 read/write

Add trace2 events to measure reading and writing the index.

Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
---
 read-cache.c | 47 ++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 46 insertions(+), 1 deletion(-)

diff --git a/read-cache.c b/read-cache.c
index 8db8dc7b4f8ca9..df50a8b727c0a6 100644
--- a/read-cache.c
+++ b/read-cache.c
@@ -2237,6 +2237,14 @@ int do_read_index(struct index_state *istate, const char *path, int must_exist)
 		load_index_extensions(&p);
 	}
 	munmap((void *)mmap, mmap_size);
+
+	/*
+	 * TODO trace2: replace "the_repository" with the actual repo instance
+	 * that is associated with the given "istate".
+	 */
+	trace2_data_intmax("index", the_repository, "read/version", istate->version);
+	trace2_data_intmax("index", the_repository, "read/cache_nr", istate->cache_nr);
+
 	return istate->cache_nr;
 
 unmap:
@@ -2268,9 +2276,17 @@ int read_index_from(struct index_state *istate, const char *path,
 	if (istate->initialized)
 		return istate->cache_nr;
 
+	/*
+	 * TODO trace2: replace "the_repository" with the actual repo instance
+	 * that is associated with the given "istate".
+	 */
+	trace2_region_enter_printf("index", "do_read_index", the_repository,
+				   "%s", path);
 	trace_performance_enter();
 	ret = do_read_index(istate, path, 0);
 	trace_performance_leave("read cache %s", path);
+	trace2_region_leave_printf("index", "do_read_index", the_repository,
+				   "%s", path);
 
 	split_index = istate->split_index;
 	if (!split_index || is_null_oid(&split_index->base_oid)) {
@@ -2286,7 +2302,11 @@ int read_index_from(struct index_state *istate, const char *path,
 
 	base_oid_hex = oid_to_hex(&split_index->base_oid);
 	base_path = xstrfmt("%s/sharedindex.%s", gitdir, base_oid_hex);
+	trace2_region_enter_printf("index", "shared/do_read_index", the_repository,
+				   "%s", base_path);
 	ret = do_read_index(split_index->base, base_path, 1);
+	trace2_region_leave_printf("index", "shared/do_read_index", the_repository,
+				   "%s", base_path);
 	if (!oideq(&split_index->base_oid, &split_index->base->oid))
 		die("broken index, expect %s in %s, got %s",
 		    base_oid_hex, base_path,
@@ -2997,6 +3017,14 @@ static int do_write_index(struct index_state *istate, struct tempfile *tempfile,
 	istate->timestamp.sec = (unsigned int)st.st_mtime;
 	istate->timestamp.nsec = ST_MTIME_NSEC(st);
 	trace_performance_since(start, "write index, changed mask = %x", istate->cache_changed);
+
+	/*
+	 * TODO trace2: replace "the_repository" with the actual repo instance
+	 * that is associated with the given "istate".
+	 */
+	trace2_data_intmax("index", the_repository, "write/version", istate->version);
+	trace2_data_intmax("index", the_repository, "write/cache_nr", istate->cache_nr);
+
 	return 0;
 }
 
@@ -3016,7 +3044,18 @@ static int commit_locked_index(struct lock_file *lk)
 static int do_write_locked_index(struct index_state *istate, struct lock_file *lock,
 				 unsigned flags)
 {
-	int ret = do_write_index(istate, lock->tempfile, 0);
+	int ret;
+
+	/*
+	 * TODO trace2: replace "the_repository" with the actual repo instance
+	 * that is associated with the given "istate".
+	 */
+	trace2_region_enter_printf("index", "do_write_index", the_repository,
+				   "%s", lock->tempfile->filename.buf);
+	ret = do_write_index(istate, lock->tempfile, 0);
+	trace2_region_leave_printf("index", "do_write_index", the_repository,
+				   "%s", lock->tempfile->filename.buf);
+
 	if (ret)
 		return ret;
 	if (flags & COMMIT_LOCK)
@@ -3110,7 +3149,13 @@ static int write_shared_index(struct index_state *istate,
 	int ret;
 
 	move_cache_to_base_index(istate);
+
+	trace2_region_enter_printf("index", "shared/do_write_index",
+				   the_repository, "%s", (*temp)->filename.buf);
 	ret = do_write_index(si->base, *temp, 1);
+	trace2_region_enter_printf("index", "shared/do_write_index",
+				   the_repository, "%s", (*temp)->filename.buf);
+
 	if (ret)
 		return ret;
 	ret = adjust_shared_perm(get_tempfile_path(*temp));

From d9bbeedabb26685b1455c962c1cc3e80c72b1aa5 Mon Sep 17 00:00:00 2001
From: Derrick Stolee <dstolee@microsoft.com>
Date: Tue, 9 Oct 2018 18:17:09 +0000
Subject: [PATCH 17/25] pack-objects: add trace2 regions

When studying the performance of 'git push' we would like to know
how much time is spent at various parts of the command. One area
that could cause performance trouble is 'git pack-objects'.

Add trace2 regions around the three main actions taken in this
command:

1. Enumerate objects.
2. Prepare pack.
3. Write pack-file.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
---
 builtin/pack-objects.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/builtin/pack-objects.c b/builtin/pack-objects.c
index 507d381153511d..5a87bb909f00e7 100644
--- a/builtin/pack-objects.c
+++ b/builtin/pack-objects.c
@@ -33,6 +33,7 @@
 #include "object-store.h"
 #include "dir.h"
 #include "midx.h"
+#include "trace2.h"
 
 #define IN_PACK(obj) oe_in_pack(&to_pack, obj)
 #define SIZE(obj) oe_size(&to_pack, obj)
@@ -3478,6 +3479,7 @@ int cmd_pack_objects(int argc, const char **argv, const char *prefix)
 		}
 	}
 
+	trace2_region_enter("pack-objects", "enumerate-objects", the_repository);
 	prepare_packing_data(&to_pack);
 
 	if (progress)
@@ -3492,12 +3494,20 @@ int cmd_pack_objects(int argc, const char **argv, const char *prefix)
 	if (include_tag && nr_result)
 		for_each_ref(add_ref_tag, NULL);
 	stop_progress(&progress_state);
+	trace2_region_leave("pack-objects", "enumerate-objects", the_repository);
 
 	if (non_empty && !nr_result)
 		return 0;
-	if (nr_result)
+	if (nr_result) {
+		trace2_region_enter("pack-objects", "prepare-pack", the_repository);
 		prepare_pack(window, depth);
+		trace2_region_leave("pack-objects", "prepare-pack", the_repository);
+	}
+
+	trace2_region_enter("pack-objects", "write-pack-file", the_repository);
 	write_pack_file();
+	trace2_region_leave("pack-objects", "write-pack-file", the_repository);
+
 	if (progress)
 		fprintf_ln(stderr,
 			   _("Total %"PRIu32" (delta %"PRIu32"),"

From 0bfdd41d746139bed793137cbbd60c4cba82bbbc Mon Sep 17 00:00:00 2001
From: Jeff Hostetler <jeffhost@microsoft.com>
Date: Mon, 5 Nov 2018 07:29:53 -0500
Subject: [PATCH 18/25] trace2:data: add subverb to checkout command

Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
---
 builtin/checkout.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/builtin/checkout.c b/builtin/checkout.c
index 011d5edb6d41a0..f7a289874684c7 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -258,6 +258,8 @@ static int checkout_paths(const struct checkout_opts *opts,
 	int errs = 0;
 	struct lock_file lock_file = LOCK_INIT;
 
+	trace2_cmd_subverb(opts->patch_mode ? "patch" : "path");
+
 	if (opts->track != BRANCH_TRACK_UNSPECIFIED)
 		die(_("'%s' cannot be used with updating paths"), "--track");
 
@@ -930,6 +932,9 @@ static int switch_branches(const struct checkout_opts *opts,
 	void *path_to_free;
 	struct object_id rev;
 	int flag, writeout_error = 0;
+
+	trace2_cmd_subverb("branch");
+
 	memset(&old_branch_info, 0, sizeof(old_branch_info));
 	old_branch_info.path = path_to_free = resolve_refdup("HEAD", 0, &rev, &flag);
 	if (old_branch_info.path)
@@ -1159,6 +1164,8 @@ static int switch_unborn_to_new_branch(const struct checkout_opts *opts)
 	int status;
 	struct strbuf branch_ref = STRBUF_INIT;
 
+	trace2_cmd_subverb("unborn");
+
 	if (!opts->new_branch)
 		die(_("You are on a branch yet to be born"));
 	strbuf_addf(&branch_ref, "refs/heads/%s", opts->new_branch);

From b006aff07a93ce8e6e291e13b85eb953fa34b773 Mon Sep 17 00:00:00 2001
From: Jeff Hostetler <jeffhost@microsoft.com>
Date: Mon, 5 Nov 2018 11:36:43 -0500
Subject: [PATCH 19/25] trace2:data: add subverb to reset command

Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
---
 builtin/reset.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/builtin/reset.c b/builtin/reset.c
index adc8e0386621bb..6af50b801c6268 100644
--- a/builtin/reset.c
+++ b/builtin/reset.c
@@ -419,6 +419,7 @@ int cmd_reset(int argc, const char **argv, const char *prefix)
 	if (patch_mode) {
 		if (reset_type != NONE)
 			die(_("--patch is incompatible with --{hard,mixed,soft}"));
+		trace2_cmd_subverb("patch-interactive");
 		return run_add_interactive(rev, "--patch=reset", &pathspec);
 	}
 
@@ -435,6 +436,13 @@ int cmd_reset(int argc, const char **argv, const char *prefix)
 	if (reset_type == NONE)
 		reset_type = MIXED; /* by default */
 
+	if (read_from_stdin)
+		trace2_cmd_subverb("path-stdin");
+	else if (pathspec.nr)
+		trace2_cmd_subverb("path");
+	else
+		trace2_cmd_subverb(reset_type_names[reset_type]);
+
 	if (reset_type != SOFT && (reset_type != MIXED || get_git_work_tree()))
 		setup_work_tree();
 

From 68d0a789d2a14ef4c2a29c4175c57c2bdc14eae2 Mon Sep 17 00:00:00 2001
From: Jeff Hostetler <jeffhost@microsoft.com>
Date: Fri, 21 Dec 2018 10:26:09 -0500
Subject: [PATCH 20/25] trace2:data: add subverb for rebase

Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
---
 builtin/rebase.c | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/builtin/rebase.c b/builtin/rebase.c
index ab321b33f96ea4..5d3be749739351 100644
--- a/builtin/rebase.c
+++ b/builtin/rebase.c
@@ -1009,6 +1009,16 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
 		ACTION_EDIT_TODO,
 		ACTION_SHOW_CURRENT_PATCH,
 	} action = NO_ACTION;
+	static const char *action_names[] = {
+		N_("undefined"),
+		N_("continue"),
+		N_("skip"),
+		N_("abort"),
+		N_("quit"),
+		N_("edit_todo"),
+		N_("show_current_patch"),
+		NULL
+	};
 	const char *gpg_sign = NULL;
 	struct string_list exec = STRING_LIST_INIT_NODUP;
 	const char *rebase_merges = NULL;
@@ -1195,6 +1205,15 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
 		die(_("The --edit-todo action can only be used during "
 		      "interactive rebase."));
 
+	if (trace2_is_enabled()) {
+		if (is_interactive(&options))
+			trace2_cmd_subverb("interactive");
+		else if (exec.nr)
+			trace2_cmd_subverb("interactive-exec");
+		else
+			trace2_cmd_subverb(action_names[action]);
+	}
+
 	switch (action) {
 	case ACTION_CONTINUE: {
 		struct object_id head;

From 7336c1099cdf468cba4920c021b0709d071e751e Mon Sep 17 00:00:00 2001
From: Jeff Hostetler <jeffhost@microsoft.com>
Date: Mon, 19 Nov 2018 16:26:37 -0500
Subject: [PATCH 21/25] trace2:data: add vfs stats

Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
---
 virtualfilesystem.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/virtualfilesystem.c b/virtualfilesystem.c
index 424680b4374530..0085e82f4d2aed 100644
--- a/virtualfilesystem.c
+++ b/virtualfilesystem.c
@@ -250,6 +250,7 @@ void apply_virtualfilesystem(struct index_state *istate)
 {
 	char *buf, *entry;
 	int i;
+	int nr_tracked = 0;
 
 	if (!git_config_get_virtualfilesystem())
 		return;
@@ -278,6 +279,7 @@ void apply_virtualfilesystem(struct index_state *istate)
 					pos = -pos - 1;
 					while (pos < istate->cache_nr && !fspathncmp(istate->cache[pos]->name, entry, len)) {
 						istate->cache[pos]->ce_flags &= ~CE_SKIP_WORKTREE;
+						nr_tracked++;
 						pos++;
 					}
 				}
@@ -288,14 +290,19 @@ void apply_virtualfilesystem(struct index_state *istate)
 						ce->ce_flags &= ~CE_SKIP_WORKTREE;
 				} else {
 					int pos = index_name_pos(istate, entry, len);
-					if (pos >= 0)
+					if (pos >= 0) {
+						nr_tracked++;
 						istate->cache[pos]->ce_flags &= ~CE_SKIP_WORKTREE;
+					}
 				}
 			}
 
 			entry += len + 1;
 		}
 	}
+
+	if (nr_tracked > 0)
+		trace2_data_intmax("vfs", the_repository, "apply/tracked", nr_tracked);
 }
 
 /*

From ba1e59f2600c8534d3e4eefe7292144944f0e71e Mon Sep 17 00:00:00 2001
From: Jeff Hostetler <jeffhost@microsoft.com>
Date: Thu, 11 Oct 2018 16:35:36 -0400
Subject: [PATCH 22/25] trace2: t/helper/test-trace2

Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
---
 Makefile                  |   1 +
 t/helper/test-tool.c      |   1 +
 t/helper/test-tool.h      |   1 +
 t/helper/test-trace2.c    | 273 ++++++++++++++++++++++++++++++++++++++
 t/t0210-trace2-normal.sh  | 135 +++++++++++++++++++
 t/t0210/scrub_normal.perl |  48 +++++++
 t/t0211-trace2-perf.sh    | 153 +++++++++++++++++++++
 t/t0211/scrub_perf.perl   |  75 +++++++++++
 t/t0212-trace2-event.sh   | 237 +++++++++++++++++++++++++++++++++
 t/t0212/parse_events.perl | 251 +++++++++++++++++++++++++++++++++++
 10 files changed, 1175 insertions(+)
 create mode 100644 t/helper/test-trace2.c
 create mode 100755 t/t0210-trace2-normal.sh
 create mode 100644 t/t0210/scrub_normal.perl
 create mode 100755 t/t0211-trace2-perf.sh
 create mode 100644 t/t0211/scrub_perf.perl
 create mode 100755 t/t0212-trace2-event.sh
 create mode 100644 t/t0212/parse_events.perl

diff --git a/Makefile b/Makefile
index f952dc2124a8fb..97b356565cb8ff 100644
--- a/Makefile
+++ b/Makefile
@@ -756,6 +756,7 @@ TEST_BUILTINS_OBJS += test-string-list.o
 TEST_BUILTINS_OBJS += test-submodule-config.o
 TEST_BUILTINS_OBJS += test-submodule-nested-repo-config.o
 TEST_BUILTINS_OBJS += test-subprocess.o
+TEST_BUILTINS_OBJS += test-trace2.o
 TEST_BUILTINS_OBJS += test-urlmatch-normalization.o
 TEST_BUILTINS_OBJS += test-wildmatch.o
 TEST_BUILTINS_OBJS += test-windows-named-pipe.o
diff --git a/t/helper/test-tool.c b/t/helper/test-tool.c
index cfb46a720ea919..da2301e5dd0b0c 100644
--- a/t/helper/test-tool.c
+++ b/t/helper/test-tool.c
@@ -51,6 +51,7 @@ static struct test_cmd cmds[] = {
 	{ "submodule-config", cmd__submodule_config },
 	{ "submodule-nested-repo-config", cmd__submodule_nested_repo_config },
 	{ "subprocess", cmd__subprocess },
+	{ "trace2", cmd__trace2 },
 	{ "urlmatch-normalization", cmd__urlmatch_normalization },
 	{ "wildmatch", cmd__wildmatch },
 #ifdef GIT_WINDOWS_NATIVE
diff --git a/t/helper/test-tool.h b/t/helper/test-tool.h
index 955490ec9f29f1..07e8fa174ee183 100644
--- a/t/helper/test-tool.h
+++ b/t/helper/test-tool.h
@@ -46,6 +46,7 @@ int cmd__string_list(int argc, const char **argv);
 int cmd__submodule_config(int argc, const char **argv);
 int cmd__submodule_nested_repo_config(int argc, const char **argv);
 int cmd__subprocess(int argc, const char **argv);
+int cmd__trace2(int argc, const char **argv);
 int cmd__urlmatch_normalization(int argc, const char **argv);
 int cmd__wildmatch(int argc, const char **argv);
 #ifdef GIT_WINDOWS_NATIVE
diff --git a/t/helper/test-trace2.c b/t/helper/test-trace2.c
new file mode 100644
index 00000000000000..b867f58d32cb36
--- /dev/null
+++ b/t/helper/test-trace2.c
@@ -0,0 +1,273 @@
+#include "test-tool.h"
+#include "cache.h"
+#include "argv-array.h"
+#include "run-command.h"
+#include "exec-cmd.h"
+#include "config.h"
+
+typedef int (fn_unit_test)(int argc, const char **argv);
+
+struct unit_test 
+{
+	fn_unit_test *ut_fn;
+	const char   *ut_name;
+	const char   *ut_usage;
+};
+
+#define MyOk    0
+#define MyError 1
+
+static int get_i(int *p_value, const char *data)
+{
+	char *endptr;
+
+	if (!data || !*data)
+		return MyError;
+
+	*p_value = strtol(data, &endptr, 10);
+	if (*endptr || errno == ERANGE)
+		return MyError;
+
+	return MyOk;
+}
+
+/*
+ * Cause process to exit with the requested value via "return".
+ *
+ * Rely on test-tool.c:cmd_main() to call trace2_cmd_exit()
+ * with our result.
+ *
+ * Test harness can confirm:
+ * [] the process-exit value.
+ * [] the "code" field in the "exit" trace2 event.
+ * [] the "code" field in the "atexit" trace2 event.
+ * [] the "name" field in the "cmd_verb" trace2 event.
+ * [] "def_param" events for all of the "interesting" pre-defined config settings.
+ */
+static int ut_001return(int argc, const char **argv)
+{
+	int rc;
+
+	if (get_i(&rc, argv[0]))
+		die("expect <exit_code>");
+
+	return rc;
+}
+
+/*
+ * Cause the process to exit with the requested value via "exit()".
+ *
+ * Test harness can confirm:
+ * [] the "code" field in the "exit" trace2 event.
+ * [] the "code" field in the "atexit" trace2 event.
+ * [] the "name" field in the "cmd_verb" trace2 event.
+ * [] "def_param" events for all of the "interesting" pre-defined config settings.
+ */
+static int ut_002exit(int argc, const char **argv)
+{
+	int rc;
+
+	if (get_i(&rc, argv[0]))
+		die("expect <exit_code>");
+
+	exit(rc);
+}
+
+/*
+ * Send an "error" event with each value in argv.  Normally, git only issues
+ * a single "error" event immediately before issuing an "exit" event (such
+ * as in die() or BUG()), but multiple "error" events are allowed.
+ *
+ * Test harness can confirm:
+ * [] a trace2 "error" event for each value in argv.
+ * [] the "name" field in the "cmd_verb" trace2 event.
+ * [] (optional) the file:line in the "exit" event refers to this function.
+ */
+static int ut_003error(int argc, const char **argv)
+{
+	int k;
+
+	if (!argv[0] || !*argv[0])
+		die("expect <error_message>");
+
+	for (k = 0; k < argc; k++)
+		error("%s", argv[k]);
+
+	return 0;
+}
+
+/*
+ * Run a child process and wait for it to finish and exit with its return code.
+ * test-tool trace2 004child [<child-command-line>]
+ *
+ * For example:
+ * test-tool trace2 004child git version
+ * test-tool trace2 004child test-tool trace2 001return 0
+ * test-tool trace2 004child test-tool trace2 004child test-tool trace2 004child
+ * test-tool trace2 004child git -c alias.xyz=version xyz
+ *
+ * Test harness can confirm:
+ * [] the "name" field in the "cmd_verb" trace2 event.
+ * [] that the outer process has a single component SID (or depth "d0" in
+ *    the PERF stream).
+ * [] that "child_start" and "child_exit" events are generated for the child.
+ * [] if the child process is an instrumented executable:
+ *    [] that "version", "start", ..., "exit", and "atexit" events are
+ *       generated by the child process.
+ *    [] that the child process events have a multiple component SID (or
+ *       depth "dN+1" in the PERF stream).
+ * [] that the child exit code is propagated to the parent process "exit"
+ *    and "atexit" events..
+ * [] (optional) that the "t_abs" field in the child process "atexit" event
+ *    is less than the "t_rel" field in the "child_exit" event of the parent
+ *    process.
+ * [] if the child process is like the alias example above,
+ *    [] (optional) the child process attempts to run "git-xyx" as a dashed
+ *       command.
+ *    [] the child process emits an "alias" event with "xyz" => "version"
+ *    [] the child process runs "git version" as a child process.
+ *    [] the child process has a 3 component SID (or depth "d2" in the PERF
+ *       stream).
+ */
+static int ut_004child(int argc, const char **argv)
+{
+	int result;
+
+	/*
+	 * Allow empty <child_command_line> so we can do arbitrarily deep
+	 * command nesting and let the last one be null.
+	 */
+	if (!argc)
+		return 0;
+
+	result = run_command_v_opt(argv, 0);
+	exit(result);
+}
+
+/*
+ * Exec a git command.  This may either create a child process (Windows)
+ * or replace the existing process.
+ * test-tool trace2 005exec <git_command_args>
+ *
+ * For example:
+ * test-tool trace2 005exec version
+ *
+ * Test harness can confirm (on Windows):
+ * [] the "name" field in the "cmd_verb" trace2 event.
+ * [] that the outer process has a single component SID (or depth "d0" in
+ *    the PERF stream).
+ * [] that "exec" and "exec_result" events are generated for the child
+ *    process (since the Windows compatibility layer fakes an exec() with
+ *    a CreateProcess(), WaitForSingleObject(), and exit()).
+ * [] that the child process has multiple component SID (or depth "dN+1"
+ *    in the PERF stream).
+ *
+ * Test harness can confirm (on platforms with a real exec() function):
+ * [] TODO talk about process replacement and how it affects SID.
+ */ 
+static int ut_005exec(int argc, const char **argv)
+{
+	int result;
+
+	if (!argc)
+		return 0;
+
+	result = execv_git_cmd(argv);
+	return result;
+}
+
+static int ut_006data(int argc, const char **argv)
+{
+	const char *usage_error =
+		"expect <cat0> <k0> <v0> [<cat1> <k1> <v1> [...]]";
+
+	if (argc % 3 != 0)
+		die("%s", usage_error);
+
+	while (argc) {
+		if (!argv[0] || !*argv[0] ||
+		    !argv[1] || !*argv[1] ||
+		    !argv[2] || !*argv[2])
+			die("%s", usage_error);
+
+		trace2_data_string(argv[0], the_repository, argv[1], argv[2]);
+		argv += 3;
+		argc -= 3;
+	}
+
+	return 0;
+}
+
+/*
+ * Usage:
+ *     test-tool trace2 <ut_name_1> <ut_usage_1>
+ *     test-tool trace2 <ut_name_2> <ut_usage_2>
+ *     ...
+ */ 
+#define USAGE_PREFIX "test-tool trace2"
+
+static struct unit_test ut_table[] = {
+	{ ut_001return,   "001return", "<exit_code>" },
+	{ ut_002exit,     "002exit",   "<exit_code>" },
+	{ ut_003error,    "003error",  "<error_message>+" },
+	{ ut_004child,    "004child",  "[<child_command_line>]" },
+	{ ut_005exec,     "005exec",   "<git_command_args>" },
+	{ ut_006data,     "006data",   "[<category> <key> <value>]+" },
+};
+
+#define for_each_ut(k, ut_k)			\
+	for (k = 0, ut_k = &ut_table[k];	\
+	     k < ARRAY_SIZE(ut_table);		\
+	     k++, ut_k = &ut_table[k])
+
+static int print_usage(void)
+{
+	int k;
+	struct unit_test *ut_k;
+
+	fprintf(stderr, "usage:\n");
+	for_each_ut(k, ut_k) {
+		fprintf(stderr, "\t%s %s %s\n",
+			USAGE_PREFIX, ut_k->ut_name, ut_k->ut_usage);
+	}
+
+	return 129;
+}
+
+/*
+ * Issue various trace2 events for testing.
+ *
+ * We assume that these trace2 routines has already been called:
+ *    [] trace2_initialize()      [common-main.c:main()]
+ *    [] trace2_cmd_start()       [common-main.c:main()]
+ *    [] trace2_cmd_verb()        [test-tool.c:cmd_main()]
+ *    [] tracd2_cmd_list_config() [test-tool.c:cmd_main()]
+ * So that:
+ *    [] the various trace2 streams are open.
+ *    [] the process SID has been created.
+ *    [] the "version" event has been generated.
+ *    [] the "start" event has been generated.
+ *    [] the "verb" event has been generated.
+ *    [] this writes various "def_param" events for interesting config values.
+ *
+ * We further assume that if we return (rather than exit()), trace2_cmd_exit()
+ * will be called by test-tool.c:cmd_main().
+ */
+int cmd__trace2(int argc, const char **argv)
+{
+	int k;
+	struct unit_test *ut_k;
+
+	argc--;	/* skip over "trace2" arg */
+	argv++;
+
+	if (argc) {
+		for_each_ut(k, ut_k) {
+			if (!strcmp(argv[0], ut_k->ut_name))
+				return ut_k->ut_fn(argc - 1, argv + 1);
+		}
+	}
+
+	return print_usage();
+}
+
diff --git a/t/t0210-trace2-normal.sh b/t/t0210-trace2-normal.sh
new file mode 100755
index 00000000000000..d53a66a3bbe78e
--- /dev/null
+++ b/t/t0210-trace2-normal.sh
@@ -0,0 +1,135 @@
+#!/bin/sh
+
+test_description='test trace2 facility (normal target)'
+. ./test-lib.sh
+
+# Add t/helper directory to PATH so that we can use a relative
+# path to run nested instances of test-tool.exe (see 004child).
+# This helps with HEREDOC comparisons later.
+TTDIR="$GIT_BUILD_DIR/t/helper/" && export TTDIR
+PATH="$TTDIR:$PATH" && export PATH
+
+TT="test-tool" && export TT
+
+# Warning: use of 'test_cmp' may run test-tool.exe and/or git.exe
+# Warning: to do the actual diff/comparison, so the HEREDOCs here
+# Warning: only cover our actual calls to test-tool and/or git.
+# Warning: So you may see extra lines in artifact files when
+# Warning: interactively debugging.
+
+# Turn off any inherited trace2 settings for this test.
+unset GIT_TR2 GIT_TR2_PERF GIT_TR2_EVENT
+unset GIT_TR2_BARE
+unset GIT_TR2_CONFIG_PARAMS
+
+V=$(git version | sed -e 's/^git version //') && export V
+
+# There are multiple trace2 targets: normal, perf, and event.
+# Trace2 events will/can be written to each active target (subject
+# to whatever filtering that target decides to do).
+# This script tests the normal target in isolation.
+
+# Enable "normal" trace2 target.
+GIT_TR2="$(pwd)/trace.normal" && export GIT_TR2
+# Enable "bare" feature which turns off "<clock> <file>:<line> " prefix.
+GIT_TR2_BARE=1 && export GIT_TR2_BARE
+
+# Basic tests of the trace2 normal stream.  Since this stream is used
+# primarily with printf-style debugging/tracing, we do limited testing
+# here.
+#
+# We do confirm the following API features:
+# [] the 'version <v>' event
+# [] the 'start <argv>' event
+# [] the 'cmd_verb <verb>' event
+# [] the 'exit <time> code:<code>' event
+# [] the 'atexit <time> code:<code>' event
+#
+# Fields of the form _FIELD_ are tokens that have been replaced (such
+# as the elapsed time).
+
+# Verb 001return
+#
+# Implicit return from cmd_<verb> function propagates <code>.
+
+test_expect_success 'normal stream, return code 0' '
+	test_when_finished "rm trace.normal actual expect" &&
+	$TT trace2 001return 0 &&
+	perl "$TEST_DIRECTORY/t0210/scrub_normal.perl" <trace.normal >actual &&
+	cat >expect <<-EOF &&
+		version $V
+		start _EXE_ trace2 001return 0
+		cmd_verb trace2 (trace2)
+		exit elapsed:_TIME_ code:0
+		atexit elapsed:_TIME_ code:0
+	EOF
+	test_cmp expect actual
+'
+
+test_expect_success 'normal stream, return code 1' '
+	test_when_finished "rm trace.normal actual expect" &&
+	test_must_fail $TT trace2 001return 1 &&
+	perl "$TEST_DIRECTORY/t0210/scrub_normal.perl" <trace.normal >actual &&
+	cat >expect <<-EOF &&
+		version $V
+		start _EXE_ trace2 001return 1
+		cmd_verb trace2 (trace2)
+		exit elapsed:_TIME_ code:1
+		atexit elapsed:_TIME_ code:1
+	EOF
+	test_cmp expect actual
+'
+
+# Verb 002exit
+#
+# Explicit exit(code) from within cmd_<verb> propagates <code>.
+
+test_expect_success 'normal stream, exit code 0' '
+	test_when_finished "rm trace.normal actual expect" &&
+	$TT trace2 002exit 0 &&
+	perl "$TEST_DIRECTORY/t0210/scrub_normal.perl" <trace.normal >actual &&
+	cat >expect <<-EOF &&
+		version $V
+		start _EXE_ trace2 002exit 0
+		cmd_verb trace2 (trace2)
+		exit elapsed:_TIME_ code:0
+		atexit elapsed:_TIME_ code:0
+	EOF
+	test_cmp expect actual
+'
+
+test_expect_success 'normal stream, exit code 1' '
+	test_when_finished "rm trace.normal actual expect" &&
+	test_must_fail $TT trace2 002exit 1 &&
+	perl "$TEST_DIRECTORY/t0210/scrub_normal.perl" <trace.normal >actual &&
+	cat >expect <<-EOF &&
+		version $V
+		start _EXE_ trace2 002exit 1
+		cmd_verb trace2 (trace2)
+		exit elapsed:_TIME_ code:1
+		atexit elapsed:_TIME_ code:1
+	EOF
+	test_cmp expect actual
+'
+
+# Verb 003error
+#
+# To the above, add multiple 'error <msg>' events
+
+test_expect_success 'normal stream, error event' '
+	test_when_finished "rm trace.normal actual expect" &&
+	$TT trace2 003error "hello world" "this is a test" &&
+	perl "$TEST_DIRECTORY/t0210/scrub_normal.perl" <trace.normal >actual &&
+	cat >expect <<-EOF &&
+		version $V
+		start _EXE_ trace2 003error '\''hello world'\'' '\''this is a test'\''
+		cmd_verb trace2 (trace2)
+		error hello world
+		error this is a test
+		exit elapsed:_TIME_ code:0
+		atexit elapsed:_TIME_ code:0
+	EOF
+	test_cmp expect actual
+'
+
+test_done
diff --git a/t/t0210/scrub_normal.perl b/t/t0210/scrub_normal.perl
new file mode 100644
index 00000000000000..c65d1a815ea3d8
--- /dev/null
+++ b/t/t0210/scrub_normal.perl
@@ -0,0 +1,48 @@
+#!/usr/bin/perl
+#
+# Scrub the variable fields from the normal trace2 output to
+# make testing easier.
+
+use strict;
+use warnings;
+
+my $float = '[0-9]*\.[0-9]+([eE][-+]?[0-9]+)?';
+
+# This code assumes that the trace2 data was written with bare
+# turned on (which omits the "<clock> <file>:<line>" prefix.
+
+while (<>) {
+    # Various messages include an elapsed time in the middle
+    # of the message.  Replace the time with a placeholder to
+    # simplify our HEREDOC in the test script.
+    s/elapsed:$float/elapsed:_TIME_/g;
+
+    my $line = $_;
+
+    # we expect:
+    #    start <argv0> [<argv1> [<argv2> [...]]]
+    #
+    # where argv0 might be a relative or absolute path, with
+    # or without quotes, and platform dependent.  Replace argv0
+    # with a token for HEREDOC matching in the test script.
+
+    if ($line =~ m/^start/) {
+	$line =~ /^start\s+(.*)/;
+	my $argv = $1;
+	$argv =~ m/(\'[^\']*\'|[^ ]+)\s+(.*)/;
+	my $argv_0 = $1;
+	my $argv_rest = $2;
+
+	print "start _EXE_ $argv_rest\n";
+    }
+    elsif ($line =~ m/^cmd_path/) {
+	# Likewise, the 'cmd_path' message breaks out argv[0].
+	#
+	# This line is only emitted when RUNTIME_PREFIX is defined,
+	# so just omit it for testing purposes.
+	# print "cmd_path _EXE_\n";
+    }
+    else {
+	print "$line";
+    }
+}
diff --git a/t/t0211-trace2-perf.sh b/t/t0211-trace2-perf.sh
new file mode 100755
index 00000000000000..24b3aff76a8cb9
--- /dev/null
+++ b/t/t0211-trace2-perf.sh
@@ -0,0 +1,153 @@
+#!/bin/sh
+
+test_description='test trace2 facility (perf target)'
+. ./test-lib.sh
+
+# Add t/helper directory to PATH so that we can use a relative
+# path to run nested instances of test-tool.exe (see 004child).
+# This helps with HEREDOC comparisons later.
+TTDIR="$GIT_BUILD_DIR/t/helper/" && export TTDIR
+PATH="$TTDIR:$PATH" && export PATH
+
+TT="test-tool" && export TT
+
+# Warning: use of 'test_cmp' may run test-tool.exe and/or git.exe
+# Warning: to do the actual diff/comparison, so the HEREDOCs here
+# Warning: only cover our actual calls to test-tool and/or git.
+# Warning: So you may see extra lines in artifact files when
+# Warning: interactively debugging.
+
+# Turn off any inherited trace2 settings for this test.
+unset GIT_TR2 GIT_TR2_PERF GIT_TR2_EVENT
+unset GIT_TR2_BARE
+unset GIT_TR2_CONFIG_PARAMS
+
+V=$(git version | sed -e 's/^git version //') && export V
+
+# There are multiple trace2 targets: normal, perf, and event.
+# Trace2 events will/can be written to each active target (subject
+# to whatever filtering that target decides to do).
+# Test each target independently.
+
+# Enable "perf" trace2 target.
+GIT_TR2_PERF="$(pwd)/trace.perf" && export GIT_TR2_PERF
+# Enable "bare" feature which turns off the prefix:
+#     "<clock> <file>:<line> | <nr_parents> | "
+GIT_TR2_BARE=1 && export GIT_TR2_BARE
+
+# Repeat some of the t0210 tests using the perf target stream instead of
+# the normal stream.
+#
+# Tokens here of the form _FIELD_ have been replaced in the observed output.
+
+# Verb 001return
+#
+# Implicit return from cmd_<verb> function propagates <code>.
+
+test_expect_success 'perf stream, return code 0' '
+	test_when_finished "rm trace.perf actual expect" &&
+	$TT trace2 001return 0 &&
+	perl "$TEST_DIRECTORY/t0211/scrub_perf.perl" <trace.perf >actual &&
+	cat >expect <<-EOF &&
+		main|version|||||$V
+		main|start|||||_EXE_ trace2 001return 0
+		main|cmd_verb|||||trace2
+		main|exit||_T_ABS_|||code:0
+		main|atexit||_T_ABS_|||code:0
+	EOF
+	test_cmp expect actual
+'
+
+test_expect_success 'perf stream, return code 1' '
+	test_when_finished "rm trace.perf actual expect" &&
+	test_must_fail $TT trace2 001return 1 &&
+	perl "$TEST_DIRECTORY/t0211/scrub_perf.perl" <trace.perf >actual &&
+	cat >expect <<-EOF &&
+		main|version|||||$V
+		main|start|||||_EXE_ trace2 001return 1
+		main|cmd_verb|||||trace2
+		main|exit||_T_ABS_|||code:1
+		main|atexit||_T_ABS_|||code:1
+	EOF
+	test_cmp expect actual
+'
+
+# Verb 003error
+#
+# To the above, add multiple 'error <msg>' events
+
+test_expect_success 'perf stream, error event' '
+	test_when_finished "rm trace.perf actual expect" &&
+	$TT trace2 003error "hello world" "this is a test" &&
+	perl "$TEST_DIRECTORY/t0211/scrub_perf.perl" <trace.perf >actual &&
+	cat >expect <<-EOF &&
+		main|version|||||$V
+		main|start|||||_EXE_ trace2 003error '\''hello world'\'' '\''this is a test'\''
+		main|cmd_verb|||||trace2
+		main|error|||||hello world
+		main|error|||||this is a test
+		main|exit||_T_ABS_|||code:0
+		main|atexit||_T_ABS_|||code:0
+	EOF
+	test_cmp expect actual
+'
+
+# Verb 004child
+#
+# Test nested spawning of child processes.
+#
+# Conceptually, this looks like:
+#    P1: TT trace2 004child
+#    P2: |--- TT trace2 004child
+#    P3:      |--- TT trace2 001return 0
+#
+# Which should generate events:
+#    P1: version
+#    P1: start
+#    P1: cmd_verb
+#    P1: child_start
+#        P2: version
+#        P2: start
+#        P2: cmd_verb
+#        P2: child_start
+#            P3: version
+#            P3: start
+#            P3: cmd_verb
+#            P3: exit
+#            P3: atexit
+#        P2: child_exit
+#        P2: exit
+#        P2: atexit
+#    P1: child_exit
+#    P1: exit
+#    P1: atexit
+
+test_expect_success 'perf stream, child processes' '
+	test_when_finished "rm trace.perf actual expect" &&
+	$TT trace2 004child $TT trace2 004child $TT trace2 001return 0 &&
+	perl "$TEST_DIRECTORY/t0211/scrub_perf.perl" <trace.perf >actual &&
+	cat >expect <<-EOF &&
+		main|version|||||$V
+		main|start|||||_EXE_ trace2 004child $TT trace2 004child $TT trace2 001return 0
+		main|cmd_verb|||||trace2
+		main|child_start||_T_ABS_|||[ch0] class:? argv: $TT trace2 004child $TT trace2 001return 0
+		main|version|||||$V
+		main|start|||||_EXE_ trace2 004child $TT trace2 001return 0
+		main|cmd_verb|||||trace2
+		main|child_start||_T_ABS_|||[ch0] class:? argv: $TT trace2 001return 0
+		main|version|||||$V
+		main|start|||||_EXE_ trace2 001return 0
+		main|cmd_verb|||||trace2
+		main|exit||_T_ABS_|||code:0
+		main|atexit||_T_ABS_|||code:0
+		main|child_exit||_T_ABS_|_T_REL_||[ch0] pid:_PID_ code:0
+		main|exit||_T_ABS_|||code:0
+		main|atexit||_T_ABS_|||code:0
+		main|child_exit||_T_ABS_|_T_REL_||[ch0] pid:_PID_ code:0
+		main|exit||_T_ABS_|||code:0
+		main|atexit||_T_ABS_|||code:0
+	EOF
+	test_cmp expect actual
+'
+
+test_done
diff --git a/t/t0211/scrub_perf.perl b/t/t0211/scrub_perf.perl
new file mode 100644
index 00000000000000..8d79f32b4ac34a
--- /dev/null
+++ b/t/t0211/scrub_perf.perl
@@ -0,0 +1,75 @@
+#!/usr/bin/perl
+#
+# Scrub the variable fields from the perf trace2 output to
+# make testing easier.
+
+use strict;
+use warnings;
+
+my $qpath = '\'[^\']*\'|[^ ]*';
+
+my $col_thread=0;
+my $col_verb=1;
+my $col_repo=2;
+my $col_t_abs=3;
+my $col_t_rel=4;
+my $col_category=5;
+my $col_rest=6;
+
+# This code assumes that the trace2 data was written with bare
+# turned on (which omits the "<clock> <file>:<line> | <parents>"
+# prefix.
+
+while (<>) {
+    my @tokens = split /\|/;
+
+    foreach my $col (@tokens) { $col =~ s/^\s+|\s+$//g; }
+
+    if ($tokens[$col_verb] =~ m/^start/) {
+	# The 'start' message lists the contents of argv in $col_rest.
+	# On some platforms (Windows), argv[0] is *sometimes* a canonical
+	# absolute path to the EXE rather than the value passed in the
+	# shell script.  Replace it with a placeholder to simplify our
+	# HEREDOC in the test script.
+	my $argv0;
+	my $argvRest;
+	$tokens[$col_rest] =~ s/^($qpath)\W*(.*)/_EXE_ $2/;
+    }
+    elsif ($tokens[$col_verb] =~ m/cmd_path/) {
+	# Likewise, the 'cmd_path' message breaks out argv[0].
+	#
+	# This line is only emitted when RUNTIME_PREFIX is defined,
+	# so just omit it for testing purposes.
+	# $tokens[$col_rest] = "_EXE_";
+	goto SKIP_LINE;
+    }
+    elsif ($tokens[$col_verb] =~ m/child_exit/) {
+	$tokens[$col_rest] =~ s/ pid:\d* / pid:_PID_ /;
+    }
+    elsif ($tokens[$col_verb] =~ m/data/) {
+	if ($tokens[$col_category] =~ m/process/) {
+	    # 'data' and 'data_json' events containing 'process'
+	    # category data are assumed to be platform-specific
+	    # and highly variable.  Just omit them.
+	    goto SKIP_LINE;
+	}
+    }
+
+    # t_abs and t_rel are either blank or a float.  Replace the float
+    # with a constant for matching the HEREDOC in the test script.
+    if ($tokens[$col_t_abs] =~ m/\d/) {
+	$tokens[$col_t_abs] = "_T_ABS_";
+    }
+    if ($tokens[$col_t_rel] =~ m/\d/) {
+	$tokens[$col_t_rel] = "_T_REL_";
+    }
+
+    my $out;
+
+    $out = join('|', @tokens);
+    print "$out\n";
+
+  SKIP_LINE:
+}
+
+
diff --git a/t/t0212-trace2-event.sh b/t/t0212-trace2-event.sh
new file mode 100755
index 00000000000000..5a9527c34f317a
--- /dev/null
+++ b/t/t0212-trace2-event.sh
@@ -0,0 +1,237 @@
+#!/bin/sh
+
+test_description='test trace2 facility'
+. ./test-lib.sh
+
+# Add t/helper directory to PATH so that we can use a relative
+# path to run nested instances of test-tool.exe (see 004child).
+# This helps with HEREDOC comparisons later.
+TTDIR="$GIT_BUILD_DIR/t/helper/" && export TTDIR
+PATH="$TTDIR:$PATH" && export PATH
+
+TT="test-tool" && export TT
+
+# Warning: use of 'test_cmp' may run test-tool.exe and/or git.exe
+# Warning: to do the actual diff/comparison, so the HEREDOCs here
+# Warning: only cover our actual calls to test-tool and/or git.
+# Warning: So you may see extra lines in artifact files when
+# Warning: interactively debugging.
+
+# Turn off any inherited trace2 settings for this test.
+unset GIT_TR2 GIT_TR2_PERF GIT_TR2_EVENT
+unset GIT_TR2_BARE
+unset GIT_TR2_CONFIG_PARAMS
+
+V=$(git version | sed -e 's/^git version //') && export V
+
+# There are multiple trace2 targets: normal, perf, and event.
+# Trace2 events will/can be written to each active target (subject
+# to whatever filtering that target decides to do).
+# Test each target independently.
+
+# Enable "event" trace2 target.
+GIT_TR2_EVENT="$(pwd)/trace.event" && export GIT_TR2_EVENT
+
+# We don't bother repeating the 001return and 002exit tests, since they
+# have coverage in the normal and perf targets.
+
+# Verb 003error
+#
+# To the above, add multiple 'error <msg>' events
+
+test_expect_success 'event stream, error event' '
+	test_when_finished "rm trace.event actual expect" &&
+	$TT trace2 003error "hello world" "this is a test" &&
+	perl "$TEST_DIRECTORY/t0212/parse_events.perl" <trace.event >actual &&
+	sed -e "s/^|//" >expect <<-EOF &&
+	|VAR1 = {
+	|  "_SID0_":{
+	|    "argv":[
+	|      "_EXE_",
+	|      "trace2",
+	|      "003error",
+	|      "hello world",
+	|      "this is a test"
+	|    ],
+	|    "errors":[
+	|      "%s",
+	|      "%s"
+	|    ],
+	|    "exit_code":0,
+	|    "verb":"trace2",
+	|    "verb_hierarchy":"trace2",
+	|    "version":"$V"
+	|  }
+	|};
+	EOF
+	test_cmp expect actual
+'
+
+# Verb 004child
+#
+# Test nested spawning of child processes.
+#
+# Conceptually, this looks like:
+#    P1: TT trace2 004child
+#    P2: |--- TT trace2 004child
+#    P3:      |--- TT trace2 001return 0
+
+test_expect_success 'event stream, return code 0' '
+#	test_when_finished "rm trace.event actual expect" &&
+	$TT trace2 004child $TT trace2 004child $TT trace2 001return 0 &&
+	perl "$TEST_DIRECTORY/t0212/parse_events.perl" <trace.event >actual &&
+	sed -e "s/^|//" >expect <<-EOF &&
+	|VAR1 = {
+	|  "_SID0_":{
+	|    "argv":[
+	|      "_EXE_",
+	|      "trace2",
+	|      "004child",
+	|      "$TT",
+	|      "trace2",
+	|      "004child",
+	|      "$TT",
+	|      "trace2",
+	|      "001return",
+	|      "0"
+	|    ],
+	|    "child":{
+	|      "0":{
+	|        "child_argv":[
+	|          "_EXE_",
+	|          "trace2",
+	|          "004child",
+	|          "$TT",
+	|          "trace2",
+	|          "001return",
+	|          "0"
+	|        ],
+	|        "child_class":"?",
+	|        "child_code":0,
+	|        "use_shell":0
+	|      }
+	|    },
+	|    "exit_code":0,
+	|    "verb":"trace2",
+	|    "verb_hierarchy":"trace2",
+	|    "version":"$V"
+	|  },
+	|  "_SID0_/_SID1_":{
+	|    "argv":[
+	|      "_EXE_",
+	|      "trace2",
+	|      "004child",
+	|      "$TT",
+	|      "trace2",
+	|      "001return",
+	|      "0"
+	|    ],
+	|    "child":{
+	|      "0":{
+	|        "child_argv":[
+	|          "_EXE_",
+	|          "trace2",
+	|          "001return",
+	|          "0"
+	|        ],
+	|        "child_class":"?",
+	|        "child_code":0,
+	|        "use_shell":0
+	|      }
+	|    },
+	|    "exit_code":0,
+	|    "verb":"trace2",
+	|    "verb_hierarchy":"trace2/trace2",
+	|    "version":"$V"
+	|  },
+	|  "_SID0_/_SID1_/_SID2_":{
+	|    "argv":[
+	|      "_EXE_",
+	|      "trace2",
+	|      "001return",
+	|      "0"
+	|    ],
+	|    "exit_code":0,
+	|    "verb":"trace2",
+	|    "verb_hierarchy":"trace2/trace2/trace2",
+	|    "version":"$V"
+	|  }
+	|};
+	EOF
+	test_cmp expect actual
+'
+
+# Test listing of all "interesting" config settings.
+
+test_expect_success 'event stream, list config' '
+	test_when_finished "rm trace.event actual expect" &&
+	git config --local t0212.abc 1 &&
+	git config --local t0212.def "hello world" &&
+	# delete events generated by the above config commands
+	rm trace.event &&
+	GIT_TR2_CONFIG_PARAMS="t0212.*" $TT trace2 001return 0 &&
+	perl "$TEST_DIRECTORY/t0212/parse_events.perl" <trace.event >actual &&
+	sed -e "s/^|//" >expect <<-EOF &&
+	|VAR1 = {
+	|  "_SID0_":{
+	|    "argv":[
+	|      "_EXE_",
+	|      "trace2",
+	|      "001return",
+	|      "0"
+	|    ],
+	|    "exit_code":0,
+	|    "params":[
+	|      {
+	|        "param":"t0212.abc",
+	|        "value":"1"
+	|      },
+	|      {
+	|        "param":"t0212.def",
+	|        "value":"hello world"
+	|      }
+	|    ],
+	|    "verb":"trace2",
+	|    "verb_hierarchy":"trace2",
+	|    "version":"$V"
+	|  }
+	|};
+	EOF
+	test_cmp expect actual
+'
+
+test_expect_success 'basic trace2_data' '
+	test_when_finished "rm trace.event actual expect" &&
+	$TT trace2 006data test_category k1 v1 test_category k2 v2 &&
+	perl "$TEST_DIRECTORY/t0212/parse_events.perl" <trace.event >actual &&
+	sed -e "s/^|//" >expect <<-EOF &&
+	|VAR1 = {
+	|  "_SID0_":{
+	|    "argv":[
+	|      "_EXE_",
+	|      "trace2",
+	|      "006data",
+	|      "test_category",
+	|      "k1",
+	|      "v1",
+	|      "test_category",
+	|      "k2",
+	|      "v2"
+	|    ],
+	|    "data":{
+	|      "test_category":{
+	|        "k1":"v1",
+	|        "k2":"v2"
+	|      }
+	|    },
+	|    "exit_code":0,
+	|    "verb":"trace2",
+	|    "verb_hierarchy":"trace2",
+	|    "version":"$V"
+	|  }
+	|};
+	EOF
+	test_cmp expect actual
+'
+
+test_done
diff --git a/t/t0212/parse_events.perl b/t/t0212/parse_events.perl
new file mode 100644
index 00000000000000..0e38fa6db66c82
--- /dev/null
+++ b/t/t0212/parse_events.perl
@@ -0,0 +1,251 @@
+#!/usr/bin/perl
+#
+# Parse event stream and convert individual events into a summary
+# record for the process.
+#
+# Git.exe generates one or more "event" records for each API method,
+# such as "start <argv>" and "exit <code>", during the life of the git
+# process.  Additionally, the input may contain interleaved events
+# from multiple concurrent git processes and/or multiple threads from
+# within a git process.
+#
+# Accumulate events for each process (based on its unique SID) in a
+# dictionary and emit process summary records.
+#
+# Convert some of the variable fields (such as elapsed time) into
+# placeholders (or omit them) to make HEREDOC comparisons easier in
+# the test scripts.
+#
+# We may also omit fields not (currently) useful for testing purposes.
+
+use strict;
+use warnings;
+use JSON::PP;
+use Data::Dumper;
+use Getopt::Long;
+
+# The version of the trace2 event target format that we understand.
+# This is reported in the 'version' event in the 'evt' field.
+# It comes from the GIT_TR2_EVENT_VERSION macro in trace2/tr2_tgt_event.c
+my $evt_version = '1';
+
+my $show_children = 1;
+my $show_exec     = 1;
+my $show_threads  = 1;
+
+# A hack to generate test HEREDOC data for pasting into the test script.
+# Usage:
+#    cd "t/trash directory.t0212-trace2-event"
+#    $TT trace ... >trace.event
+#    VV=$(../../git.exe version | sed -e 's/^git version //')
+#    perl ../t0212/parse_events.perl --HEREDOC --VERSION=$VV <trace.event >heredoc
+# Then paste heredoc into your new test.
+
+my $gen_heredoc = 0;
+my $gen_version = '';
+
+GetOptions("children!" => \$show_children,
+	   "exec!"     => \$show_exec,
+	   "threads!"  => \$show_threads,
+	   "HEREDOC!"  => \$gen_heredoc,
+	   "VERSION=s" => \$gen_version    )
+    or die("Error in command line arguments\n");
+
+
+# SIDs contains timestamps and PIDs of the process and its parents.
+# This makes it difficult to match up in a HEREDOC in the test script.
+# Build a map from actual SIDs to predictable constant values and yet
+# keep the parent/child relationships.  For example:
+# {..., "sid":"1539706952458276-8652", ...}
+# {..., "sid":"1539706952458276-8652/1539706952649493-15452", ...}
+# becomes:
+# {..., "sid":"_SID1_", ...}
+# {..., "sid":"_SID1_/_SID2_", ...}
+my $sid_map;
+my $sid_count = 0;
+
+my $processes;
+
+while (<>) {
+    my $line = decode_json( $_ );
+
+    my $sid = "";
+    my $sid_sep = "";
+
+    my $raw_sid = $line->{'sid'};
+    my @raw_sid_parts = split /\//, $raw_sid;
+    foreach my $raw_sid_k (@raw_sid_parts) {
+	if (!exists $sid_map->{$raw_sid_k}) {
+	    $sid_map->{$raw_sid_k} = '_SID' . $sid_count . '_';
+	    $sid_count++;
+	}
+	$sid = $sid . $sid_sep . $sid_map->{$raw_sid_k};
+	$sid_sep = '/';
+    }
+    
+    my $event = $line->{'event'};
+
+    if ($event eq 'version') {
+	$processes->{$sid}->{'version'} = $line->{'exe'};
+	if ($gen_heredoc == 1 && $gen_version eq $line->{'exe'}) {
+	    # If we are generating data FOR the test script, replace
+	    # the reported git.exe version with a reference to an
+	    # environment variable.  When our output is pasted into
+	    # the test script, it will then be expanded in future
+	    # test runs to the THEN current version of git.exe.
+	    # We assume that the test script uses env var $V.
+	    $processes->{$sid}->{'version'} = "\$V";
+	}
+    }
+
+    elsif ($event eq 'start') {
+	$processes->{$sid}->{'argv'} = $line->{'argv'};
+	$processes->{$sid}->{'argv'}[0] = "_EXE_";
+    }
+
+    elsif ($event eq 'exit') {
+	$processes->{$sid}->{'exit_code'} = $line->{'code'};
+    }
+
+    elsif ($event eq 'atexit') {
+	$processes->{$sid}->{'exit_code'} = $line->{'code'};
+    }
+
+    elsif ($event eq 'error') {
+	# For HEREDOC purposes, use the error message format string if
+	# available, rather than the formatted message (which probably
+	# has an absolute pathname).
+	if (exists $line->{'fmt'}) {
+	    push( @{$processes->{$sid}->{'errors'}}, $line->{'fmt'} );
+	}
+	elsif (exists $line->{'msg'}) {
+	    push( @{$processes->{$sid}->{'errors'}}, $line->{'msg'} );
+	}
+    }
+
+    elsif ($event eq 'cmd_path') {
+	## $processes->{$sid}->{'path'} = $line->{'path'};
+	#
+	# Like in the 'start' event, we need to replace the value of
+	# argv[0] with a token for HEREDOC purposes.  However, the
+	# event is only emitted when RUNTIME_PREFIX is defined, so
+	# just omit it for testing purposes.
+	# $processes->{$sid}->{'path'} = "_EXE_";
+    }
+    
+    elsif ($event eq 'cmd_verb') {
+	$processes->{$sid}->{'verb'} = $line->{'name'};
+	$processes->{$sid}->{'verb_hierarchy'} = $line->{'hierarchy'};
+    }
+
+    elsif ($event eq 'alias') {
+	$processes->{$sid}->{'alias'}->{'key'} = $line->{'alias'};
+	$processes->{$sid}->{'alias'}->{'argv'} = $line->{'argv'};
+    }
+
+    elsif ($event eq 'def_param') {
+	my $kv;
+	$kv->{'param'} = $line->{'param'};
+	$kv->{'value'} = $line->{'value'};
+	push( @{$processes->{$sid}->{'params'}}, $kv );
+    }
+
+    elsif ($event eq 'child_start') {
+	if ($show_children == 1) {
+	    $processes->{$sid}->{'child'}->{$line->{'child_id'}}->{'child_class'} = $line->{'child_class'};
+	    $processes->{$sid}->{'child'}->{$line->{'child_id'}}->{'child_argv'} = $line->{'argv'};
+	    $processes->{$sid}->{'child'}->{$line->{'child_id'}}->{'child_argv'}[0] = "_EXE_";
+	    $processes->{$sid}->{'child'}->{$line->{'child_id'}}->{'use_shell'} = $line->{'use_shell'} ? 1 : 0;
+	}
+    }
+
+    elsif ($event eq 'child_exit') {
+	if ($show_children == 1) {
+	    $processes->{$sid}->{'child'}->{$line->{'child_id'}}->{'child_code'} = $line->{'code'};
+	}
+    }
+
+    # TODO decide what information we want to test from thread events.
+
+    elsif ($event eq 'thread_start') {
+	if ($show_threads == 1) {
+	}
+    }
+
+    elsif ($event eq 'thread_exit') {
+	if ($show_threads == 1) {
+	}
+    }
+
+    # TODO decide what information we want to test from exec events.
+
+    elsif ($event eq 'exec') {
+	if ($show_exec == 1) {
+	}
+    }
+
+    elsif ($event eq 'exec_result') {
+	if ($show_exec == 1) {
+	}
+    }
+
+    elsif ($event eq 'def_param') {
+	# Accumulate parameter key/value pairs by key rather than in an array
+	# so that we get overwrite (last one wins) effects.
+	$processes->{$sid}->{'params'}->{$line->{'param'}} = $line->{'value'};
+    }
+
+    elsif ($event eq 'def_repo') {
+	# $processes->{$sid}->{'repos'}->{$line->{'repo'}} = $line->{'worktree'};
+	$processes->{$sid}->{'repos'}->{$line->{'repo'}} = "_WORKTREE_";
+    }
+
+    # A series of potentially nested and threaded region and data events
+    # is fundamentally incompatibile with the type of summary record we
+    # are building in this script.  Since they are intended for
+    # perf-trace-like analysis rather than a result summary, we ignore
+    # most of them here.
+
+    # elsif ($event eq 'region_enter') {
+    # }
+    # elsif ($event eq 'region_leave') {
+    # }
+
+    elsif ($event eq 'data') {
+	my $cat = $line->{'category'};
+	if ($cat eq 'test_category') {
+	    
+	    my $key = $line->{'key'};
+	    my $value = $line->{'value'};
+	    $processes->{$sid}->{'data'}->{$cat}->{$key} = $value;
+	}
+    }
+
+    # This trace2 target does not emit 'printf' events.
+    #
+    # elsif ($event eq 'printf') {
+    # }
+}
+
+# Dump the resulting hash into something that we can compare against
+# in the test script.  These options make Dumper output look a little
+# bit like JSON.  Also convert variable references of the form "$VAR*"
+# so that the matching HEREDOC doesn't need to escape it.
+
+$Data::Dumper::Sortkeys = 1;
+$Data::Dumper::Indent = 1;
+$Data::Dumper::Purity = 1;
+$Data::Dumper::Pair = ':';
+
+my $out = Dumper($processes);
+$out =~ s/'/"/g;
+$out =~ s/\$VAR/VAR/g;
+
+# Finally, if we're running this script to generate (manually confirmed)
+# data to add to the test script, guard the indentation.
+
+if ($gen_heredoc == 1) {
+    $out =~ s/^/\t\|/gms;
+}
+
+print $out;

From a4958826e1ca4b32d77064a29c82cdee11a93dff Mon Sep 17 00:00:00 2001
From: Jeff Hostetler <jeffhost@microsoft.com>
Date: Fri, 12 Oct 2018 13:16:58 -0400
Subject: [PATCH 23/25] DROPME: keep inherited GIT_TR2 env vars when running
 test suite

Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
---
 t/test-lib.sh | 1 +
 1 file changed, 1 insertion(+)

diff --git a/t/test-lib.sh b/t/test-lib.sh
index 51f502b1614167..fca8f4b837b59a 100644
--- a/t/test-lib.sh
+++ b/t/test-lib.sh
@@ -146,6 +146,7 @@ unset VISUAL EMAIL LANGUAGE COLUMNS $(env | sed -n \
 	-e '/^GIT_PERF_/d' \
 	-e '/^GIT_CURL_VERBOSE/d' \
 	-e '/^GIT_TRACE_CURL/d' \
+	-e '/^GIT_TR2_*/d' \
 	-e 's/^\(GIT_[^=]*\)=.*/\1/p')
 unset XDG_CACHE_HOME
 unset XDG_CONFIG_HOME

From dc8019ee1cccac3fa3617b33a51908fedbcdcbf1 Mon Sep 17 00:00:00 2001
From: Jeff Hostetler <jeffhost@microsoft.com>
Date: Wed, 26 Sep 2018 12:29:26 -0400
Subject: [PATCH 24/25] gvfs:trace2:data: add trace2 tracing around
 read_object_process

Add trace2 region around read_object_process to collect
time spent waiting for missing objects to be dynamically
fetched.

Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
---
 sha1-file.c | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/sha1-file.c b/sha1-file.c
index d0ea83fb1e3132..4f829e8c608db5 100644
--- a/sha1-file.c
+++ b/sha1-file.c
@@ -745,6 +745,8 @@ static int read_object_process(const struct object_id *oid)
 
 	start = getnanotime();
 
+	trace2_region_enter("subprocess", "read_object", the_repository);
+
 	if (!subprocess_map_initialized) {
 		subprocess_map_initialized = 1;
 		hashmap_init(&subprocess_map, (hashmap_cmp_fn)cmd2process_cmp,
@@ -761,13 +763,16 @@ static int read_object_process(const struct object_id *oid)
 		if (subprocess_start(&subprocess_map, &entry->subprocess, cmd,
 				     start_read_object_fn)) {
 			free(entry);
-			return -1;
+			err = -1;
+			goto leave_region;
 		}
 	}
 	process = &entry->subprocess.process;
 
-	if (!(CAP_GET & entry->supported_capabilities))
-		return -1;
+	if (!(CAP_GET & entry->supported_capabilities)) {
+		err = -1;
+		goto leave_region;
+	}
 
 	sigchain_push(SIGPIPE, SIG_IGN);
 
@@ -816,6 +821,10 @@ static int read_object_process(const struct object_id *oid)
 
 	trace_performance_since(start, "read_object_process");
 
+leave_region:
+	trace2_region_leave_printf("subprocess", "read_object", the_repository,
+				   "result %d", err);
+
 	return err;
 }
 

From f4e9264f145306881f532f305b4e051a0572c033 Mon Sep 17 00:00:00 2001
From: Jeff Hostetler <jeffhost@microsoft.com>
Date: Wed, 26 Sep 2018 11:21:22 -0400
Subject: [PATCH 25/25] gvfs:trace2:data add status
 serialization/deserialization information

Add trace2 region and data events describing attempts to deserialize
status data using a status cache.

A category:status, label:deserialize region is pushed around the
deserialize code.

Deserialization results when reading from a file are:
    category:status, path   = <path>
    category:status, polled = <number_of_attempts>
    category:status, result = "ok" | "reject"

When reading from STDIN are:
    category:status, path   = "STDIN"
    category:status, result = "ok" | "reject"

Status will fallback and run a normal status scan when a "reject"
is reported (unless "--deserialize-wait=fail").

If "ok" is reported, status was able to use the status cache and
avoid scanning the workdir.

Additionally, a sub-verb is emitted for each step: collection,
deserialization, and serialization.  For example, if deserialization
is attempted and fails and status falls back to actually computing
the status, a sub-verb message containing "deserialize" is issued
and then a sub-verb for "collect" is issued.

Also, if deserialization fails, a data message containing the
rejection reason is emitted.

Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
---
 builtin/commit.c        | 19 +++++++++++-
 wt-status-deserialize.c | 66 ++++++++++++++++++++++++++++++++++++++---
 wt-status.h             |  2 ++
 3 files changed, 82 insertions(+), 5 deletions(-)

diff --git a/builtin/commit.c b/builtin/commit.c
index 03dfd4043442a9..3e863ae1b631e8 100644
--- a/builtin/commit.c
+++ b/builtin/commit.c
@@ -145,6 +145,7 @@ static int opt_parse_porcelain(const struct option *opt, const char *arg, int un
 static int do_serialize = 0;
 static char *serialize_path = NULL;
 
+static int reject_implicit = 0;
 static int do_implicit_deserialize = 0;
 static int do_explicit_deserialize = 0;
 static char *deserialize_path = NULL;
@@ -202,7 +203,7 @@ static int opt_parse_deserialize(const struct option *opt, const char *arg, int
 		if (arg) /* override config or stdin */
 			deserialize_path = xstrdup(arg);
 		if (deserialize_path && *deserialize_path
-		    && (access(deserialize_path, R_OK) != 0))
+		    && (wt_status_deserialize_access(deserialize_path, R_OK) != 0))
 			die("cannot find serialization file '%s'",
 			    deserialize_path);
 
@@ -1396,6 +1397,8 @@ static int git_status_config(const char *k, const char *v, void *cb)
 		if (v && *v && access(v, R_OK) == 0) {
 			do_implicit_deserialize = 1;
 			deserialize_path = xstrdup(v);
+		} else {
+			reject_implicit = 1;
 		}
 		return 0;
 	}
@@ -1552,6 +1555,17 @@ int cmd_status(int argc, const char **argv, const char *prefix)
 			   (do_implicit_deserialize || do_explicit_deserialize));
 	if (try_deserialize)
 		goto skip_init;
+	/*
+	 * If we implicitly received a status cache pathname from the config
+	 * and the file does not exist, we silently reject it and do the normal
+	 * status "collect".  Fake up some trace2 messages to reflect this and
+	 * assist post-processors know this case is different.
+	 */
+	if (!do_serialize && reject_implicit) {
+		trace2_cmd_subverb("implicit-deserialize");
+		trace2_data_string("status", the_repository, "deserialize/reject",
+				   "status-cache/access");
+	}
 
 	enable_fscache(0);
 	if (status_format != STATUS_FORMAT_PORCELAIN &&
@@ -1595,6 +1609,7 @@ int cmd_status(int argc, const char **argv, const char *prefix)
 		if (s.relative_paths)
 			s.prefix = prefix;
 
+		trace2_cmd_subverb("deserialize");
 		result = wt_status_deserialize(&s, deserialize_path, dw);
 		if (result == DESERIALIZE_OK)
 			return 0;
@@ -1612,6 +1627,7 @@ int cmd_status(int argc, const char **argv, const char *prefix)
 			fd = -1;
 	}
 
+	trace2_cmd_subverb("collect");
 	wt_status_collect(&s);
 
 	if (0 <= fd)
@@ -1626,6 +1642,7 @@ int cmd_status(int argc, const char **argv, const char *prefix)
 		if (fd_serialize < 0)
 			die_errno(_("could not serialize to '%s'"),
 				  serialize_path);
+		trace2_cmd_subverb("serialize");
 		wt_status_serialize_v1(fd_serialize, &s);
 		close(fd_serialize);
 	}
diff --git a/wt-status-deserialize.c b/wt-status-deserialize.c
index 23b2f69798bb8a..c8a059bf2aa715 100644
--- a/wt-status-deserialize.c
+++ b/wt-status-deserialize.c
@@ -3,6 +3,22 @@
 #include "pkt-line.h"
 #include "trace.h"
 
+static void set_deserialize_reject_reason(const char *reason)
+{
+	trace2_data_string("status", the_repository, "deserialize/reject",
+			   reason);
+}
+
+int wt_status_deserialize_access(const char *path, int mode)
+{
+	int a = access(path, mode);
+
+	if (a != 0)
+		set_deserialize_reject_reason("status-cache/access");
+
+	return a;
+}
+
 static struct trace_key trace_deserialize = TRACE_KEY_INIT(DESERIALIZE);
 
 enum deserialize_parse_strategy {
@@ -49,6 +65,7 @@ static int my_validate_index(const struct cache_time *mtime_reported)
 	struct cache_time mtime_observed_on_disk;
 
 	if (lstat(path, &st)) {
+		set_deserialize_reject_reason("index/not-found");
 		trace_printf_key(&trace_deserialize, "could not stat index");
 		return DESERIALIZE_ERR;
 	}
@@ -56,6 +73,7 @@ static int my_validate_index(const struct cache_time *mtime_reported)
 	mtime_observed_on_disk.nsec = ST_MTIME_NSEC(st);
 	if ((mtime_observed_on_disk.sec != mtime_reported->sec) ||
 	    (mtime_observed_on_disk.nsec != mtime_reported->nsec)) {
+		set_deserialize_reject_reason("index/mtime-changed");
 		trace_printf_key(&trace_deserialize,
 				 "index mtime changed [des %d %d][obs %d %d]",
 			     mtime_reported->sec, mtime_reported->nsec,
@@ -81,10 +99,12 @@ static int my_validate_excludes(const char *path, const char *key, const char *l
 
 	r = (strcmp(line, sb.buf) ? DESERIALIZE_ERR : DESERIALIZE_OK);
 
-	if (r == DESERIALIZE_ERR)
+	if (r == DESERIALIZE_ERR) {
+		set_deserialize_reject_reason("excludes/changed");
 		trace_printf_key(&trace_deserialize,
 				 "%s changed [cached '%s'][observed '%s']",
 				 key, line, sb.buf);
+	}
 
 	strbuf_release(&sb);
 	return r;
@@ -140,6 +160,7 @@ static int wt_deserialize_v1_header(struct wt_status *s, int fd)
 					   &index_mtime.sec,
 					   &index_mtime.nsec);
 			if (nr_fields != 2) {
+				set_deserialize_reject_reason("v1-header/invalid-index-mtime");
 				trace_printf_key(&trace_deserialize, "invalid index_mtime (%d) '%s'",
 					     nr_fields, line);
 				return DESERIALIZE_ERR;
@@ -223,6 +244,7 @@ static int wt_deserialize_v1_header(struct wt_status *s, int fd)
 		/* status_format */
 		if (skip_prefix(line, "sha1_commit ", &arg)) {
 			if (get_sha1_hex(arg, s->sha1_commit)) {
+				set_deserialize_reject_reason("v1-header/invalid-commit-sha");
 				trace_printf_key(&trace_deserialize, "invalid sha1_commit");
 				return DESERIALIZE_ERR;
 			}
@@ -238,19 +260,23 @@ static int wt_deserialize_v1_header(struct wt_status *s, int fd)
 		}
 		/* prefix */
 
+		set_deserialize_reject_reason("v1-header/unexpected-line");
 		trace_printf_key(&trace_deserialize, "unexpected line '%s'", line);
 		return DESERIALIZE_ERR;
 	}
 
 	if (!have_required_index_mtime) {
+		set_deserialize_reject_reason("v1-header/missing-index-mtime");
 		trace_printf_key(&trace_deserialize, "missing '%s'", "index_mtime");
 		return DESERIALIZE_ERR;
 	}
 	if (!have_required_core_excludes) {
+		set_deserialize_reject_reason("v1-header/missing-core-excludes");
 		trace_printf_key(&trace_deserialize, "missing '%s'", "core_excludes");
 		return DESERIALIZE_ERR;
 	}
 	if (!have_required_repo_excludes) {
+		set_deserialize_reject_reason("v1-header/missing-repo-excludes");
 		trace_printf_key(&trace_deserialize, "missing '%s'", "repo_excludes");
 		return DESERIALIZE_ERR;
 	}
@@ -336,6 +362,7 @@ static int wt_deserialize_v1_changed_items(const struct wt_status *cmd_s,
 			 * So we reject the status cache and let the fallback
 			 * code run.
 			 */
+			set_deserialize_reject_reason("v1-data/unmerged");
 			trace_printf_key(
 				&trace_deserialize,
 				"reject: V2 format and umerged file: %s",
@@ -471,6 +498,7 @@ static int wt_deserialize_v1(const struct wt_status *cmd_s, struct wt_status *s,
 	 * the serialized data
 	*/
 	if (validate_untracked_files_arg(cmd_s->show_untracked_files, s->show_untracked_files, &untracked_strategy)) {
+		set_deserialize_reject_reason("args/untracked-files");
 		trace_printf_key(&trace_deserialize, "reject: show_untracked_file: command: %d, serialized : %d",
 				cmd_s->show_untracked_files,
 				s->show_untracked_files);
@@ -478,6 +506,7 @@ static int wt_deserialize_v1(const struct wt_status *cmd_s, struct wt_status *s,
 	}
 
 	if (validate_ignored_files_arg(cmd_s->show_ignored_mode, s->show_ignored_mode, &ignored_strategy)) {
+		set_deserialize_reject_reason("args/ignored-mode");
 		trace_printf_key(&trace_deserialize, "reject: show_ignored_mode: command: %d, serialized: %d",
 				cmd_s->show_ignored_mode,
 				s->show_ignored_mode);
@@ -511,6 +540,7 @@ static int wt_deserialize_v1(const struct wt_status *cmd_s, struct wt_status *s,
 				return DESERIALIZE_ERR;
 			continue;
 		}
+		set_deserialize_reject_reason("v1-data/unexpected-line");
 		trace_printf_key(&trace_deserialize, "unexpected line '%s'", line);
 		return DESERIALIZE_ERR;
 	}
@@ -532,6 +562,7 @@ static int wt_deserialize_parse(const struct wt_status *cmd_s, struct wt_status
 		if (version == 1)
 			return wt_deserialize_v1(cmd_s, s, fd);
 	}
+	set_deserialize_reject_reason("status-cache/unsupported-version");
 	trace_printf_key(&trace_deserialize, "missing/unsupported version");
 	return DESERIALIZE_ERR;
 }
@@ -552,6 +583,7 @@ static int wt_deserialize_fd(const struct wt_status *cmd_s, struct wt_status *de
 	 * Check the path spec on the current command
 	 */
 	if (cmd_s->pathspec.nr > 1) {
+		set_deserialize_reject_reason("args/multiple-pathspecs");
 		trace_printf_key(&trace_deserialize, "reject: multiple pathspecs");
 		return DESERIALIZE_ERR;
 	}
@@ -562,6 +594,7 @@ static int wt_deserialize_fd(const struct wt_status *cmd_s, struct wt_status *de
 	 */
 	if (cmd_s->pathspec.nr == 1 &&
 		my_strcmp_null(cmd_s->pathspec.items[0].match, "")) {
+		set_deserialize_reject_reason("args/root-pathspec");
 		trace_printf_key(&trace_deserialize, "reject: pathspec");
 		return DESERIALIZE_ERR;
 	}
@@ -578,20 +611,24 @@ static int wt_deserialize_fd(const struct wt_status *cmd_s, struct wt_status *de
 	 * or "--ignored" settings).
 	 */
 	if (cmd_s->is_initial != des_s->is_initial) {
+		set_deserialize_reject_reason("args/is-initial-changed");
 		trace_printf_key(&trace_deserialize, "reject: is_initial");
 		return DESERIALIZE_ERR;
 	}
 	if (my_strcmp_null(cmd_s->branch, des_s->branch)) {
+		set_deserialize_reject_reason("args/branch-changed");
 		trace_printf_key(&trace_deserialize, "reject: branch");
 		return DESERIALIZE_ERR;
 	}
 	if (my_strcmp_null(cmd_s->reference, des_s->reference)) {
+		set_deserialize_reject_reason("args/reference-changed");
 		trace_printf_key(&trace_deserialize, "reject: reference");
 		return DESERIALIZE_ERR;
 	}
 	/* verbose */
 	/* amend */
 	if (cmd_s->whence != des_s->whence) {
+		set_deserialize_reject_reason("args/whence-changed");
 		trace_printf_key(&trace_deserialize, "reject: whence");
 		return DESERIALIZE_ERR;
 	}
@@ -625,19 +662,23 @@ static int wt_deserialize_fd(const struct wt_status *cmd_s, struct wt_status *de
 	/* hints */
 	/* ahead_behind_flags */
 	if (cmd_s->detect_rename != des_s->detect_rename) {
+		set_deserialize_reject_reason("args/detect-rename-changed");
 		trace_printf_key(&trace_deserialize, "reject: detect_rename");
 		return DESERIALIZE_ERR;
 	}
 	if (cmd_s->rename_score != des_s->rename_score) {
+		set_deserialize_reject_reason("args/rename-score-changed");
 		trace_printf_key(&trace_deserialize, "reject: rename_score");
 		return DESERIALIZE_ERR;
 	}
 	if (cmd_s->rename_limit != des_s->rename_limit) {
+		set_deserialize_reject_reason("args/rename-limit-changed");
 		trace_printf_key(&trace_deserialize, "reject: rename_limit");
 		return DESERIALIZE_ERR;
 	}
 	/* status_format */
 	if (hashcmp(cmd_s->sha1_commit, des_s->sha1_commit)) {
+		set_deserialize_reject_reason("args/commit-changed");
 		trace_printf_key(&trace_deserialize, "reject: sha1_commit");
 		return DESERIALIZE_ERR;
 	}
@@ -725,15 +766,18 @@ static int try_deserialize_read_from_file(const struct wt_status *cmd_s,
 					  enum wt_status_deserialize_wait dw,
 					  struct wt_status *des_s)
 {
-	int k, limit;
+	int k = 0;
+	int limit;
 	int result = DESERIALIZE_ERR;
 
 	/*
 	 * For "fail" or "no", try exactly once to read the status cache.
 	 * Return an error if the file is stale.
 	 */
-	if (dw == DESERIALIZE_WAIT__FAIL || dw == DESERIALIZE_WAIT__NO)
-		return try_deserialize_read_from_file_1(cmd_s, path, des_s);
+	if (dw == DESERIALIZE_WAIT__FAIL || dw == DESERIALIZE_WAIT__NO) {
+		result = try_deserialize_read_from_file_1(cmd_s, path, des_s);
+		goto done;
+	}
 
 	/*
 	 * Wait for the status cache file to refresh.  Wait duration can
@@ -758,6 +802,12 @@ static int try_deserialize_read_from_file(const struct wt_status *cmd_s,
 		sleep_millisec(100);
 	}
 
+done:
+	trace2_data_string("status", the_repository, "deserialize/path", path);
+	trace2_data_intmax("status", the_repository, "deserialize/polled", k);
+	trace2_data_string("status", the_repository, "deserialize/result",
+			   ((result == DESERIALIZE_OK) ? "ok" : "reject"));
+
 	trace_printf_key(&trace_deserialize,
 			 "wait polled=%d result=%d '%s'",
 			 k, result, path);
@@ -783,6 +833,8 @@ int wt_status_deserialize(const struct wt_status *cmd_s,
 	struct wt_status des_s;
 	int result;
 
+	trace2_region_enter("status", "deserialize", the_repository);
+
 	if (path && *path && strcmp(path, "0")) {
 		result = try_deserialize_read_from_file(cmd_s, path, dw, &des_s);
 	} else {
@@ -793,8 +845,14 @@ int wt_status_deserialize(const struct wt_status *cmd_s,
 		 * term, since we cannot read stdin multiple times.
 		 */
 		result = wt_deserialize_fd(cmd_s, &des_s, 0);
+
+		trace2_data_string("status", the_repository, "deserialize/path", "STDIN");
+		trace2_data_string("status", the_repository, "deserialize/result",
+				   ((result == DESERIALIZE_OK) ? "ok" : "reject"));
 	}
 
+	trace2_region_leave("status", "deserialize", the_repository);
+
 	if (result == DESERIALIZE_OK) {
 		wt_status_get_state(&des_s.state, des_s.branch &&
 				    !strcmp(des_s.branch, "HEAD"));
diff --git a/wt-status.h b/wt-status.h
index ca0ac6fab38c6b..5245178d7fba03 100644
--- a/wt-status.h
+++ b/wt-status.h
@@ -210,6 +210,8 @@ int wt_status_deserialize(const struct wt_status *cmd_s,
 			  const char *path,
 			  enum wt_status_deserialize_wait dw);
 
+int wt_status_deserialize_access(const char *path, int mode);
+
 /*
  * A helper routine for serialize and deserialize to compute
  * metadata for the user-global and repo-local excludes files.