From bb695d1c39470be1cd13e5797d494b7a7694d147 Mon Sep 17 00:00:00 2001 From: Nick Terrell Date: Mon, 15 Nov 2021 19:08:19 -0800 Subject: [PATCH 1/3] lib: zstd: Fix unused variable warning Backport the fix from upstream PR #2838 [0]. Found by the Kernel test robot in [1]. [0] https://github.com/facebook/zstd/pull/2838 [1] https://lore.kernel.org/linux-mm/202111120312.833wII4i-lkp@intel.com/T/ Reported-by: kernel test robot Signed-off-by: Nick Terrell --- lib/zstd/compress/zstd_compress_superblock.c | 1 + 1 file changed, 1 insertion(+) diff --git a/lib/zstd/compress/zstd_compress_superblock.c b/lib/zstd/compress/zstd_compress_superblock.c index ee03e0aedb0304..a6a8e9a2aa0e33 100644 --- a/lib/zstd/compress/zstd_compress_superblock.c +++ b/lib/zstd/compress/zstd_compress_superblock.c @@ -411,6 +411,7 @@ static size_t ZSTD_seqDecompressedSize(seqStore_t const* seqStore, const seqDef* const seqDef* sp = sstart; size_t matchLengthSum = 0; size_t litLengthSum = 0; + (void)litLengthSum; while (send-sp > 0) { ZSTD_sequenceLength const seqLen = ZSTD_getSequenceLength(seqStore, sp); litLengthSum += seqLen.litLength; From 1b3f7e9f8013e9978e6db91af0daab3f800e58ea Mon Sep 17 00:00:00 2001 From: Nick Terrell Date: Mon, 15 Nov 2021 20:33:08 -0800 Subject: [PATCH 2/3] lib: zstd: Don't inline functions in zstd_opt.c `zstd_opt.c` contains the match finder for the highest compression levels. These levels are already very slow, and are unlikely to be used in the kernel. If they are used, they shouldn't be used in latency sensitive workloads, so slowing them down shouldn't be a big deal. This saves 188 KB of the 288 KB regression reported by Geert Uytterhoeven [0]. I've also opened an issue upstream [1] so that we can properly tackle the code size issue in `zstd_opt.c` for all users, and can hopefully remove this hack in the next zstd version we import. Bloat-o-meter output on x86-64: ``` > ../scripts/bloat-o-meter vmlinux.old vmlinux add/remove: 6/5 grow/shrink: 1/9 up/down: 16673/-209939 (-193266) Function old new delta ZSTD_compressBlock_opt_generic.constprop - 7559 +7559 ZSTD_insertBtAndGetAllMatches - 6304 +6304 ZSTD_insertBt1 - 1731 +1731 ZSTD_storeSeq - 693 +693 ZSTD_BtGetAllMatches - 255 +255 ZSTD_updateRep - 128 +128 ZSTD_updateTree 96 99 +3 ZSTD_insertAndFindFirstIndexHash3 81 - -81 ZSTD_setBasePrices.constprop 98 - -98 ZSTD_litLengthPrice.constprop 138 - -138 ZSTD_count 362 181 -181 ZSTD_count_2segments 1407 938 -469 ZSTD_insertBt1.constprop 2689 - -2689 ZSTD_compressBlock_btultra2 19990 423 -19567 ZSTD_compressBlock_btultra 19633 15 -19618 ZSTD_initStats_ultra 19825 - -19825 ZSTD_compressBlock_btopt 20374 12 -20362 ZSTD_compressBlock_btopt_extDict 29984 12 -29972 ZSTD_compressBlock_btultra_extDict 30718 15 -30703 ZSTD_compressBlock_btopt_dictMatchState 32689 12 -32677 ZSTD_compressBlock_btultra_dictMatchState 33574 15 -33559 Total: Before=6611828, After=6418562, chg -2.92% ``` [0] https://lkml.org/lkml/2021/11/14/189 [1] https://github.com/facebook/zstd/issues/2862 Reported-by: Geert Uytterhoeven Signed-off-by: Nick Terrell --- lib/zstd/common/compiler.h | 7 +++++++ lib/zstd/compress/zstd_opt.c | 14 +++++++++++++- 2 files changed, 20 insertions(+), 1 deletion(-) diff --git a/lib/zstd/common/compiler.h b/lib/zstd/common/compiler.h index a1a051e4bce66c..f5a9c70a228a2b 100644 --- a/lib/zstd/common/compiler.h +++ b/lib/zstd/common/compiler.h @@ -16,6 +16,7 @@ *********************************************************/ /* force inlining */ +#if !defined(ZSTD_NO_INLINE) #if (defined(__GNUC__) && !defined(__STRICT_ANSI__)) || defined(__cplusplus) || defined(__STDC_VERSION__) && __STDC_VERSION__ >= 199901L /* C99 */ # define INLINE_KEYWORD inline #else @@ -24,6 +25,12 @@ #define FORCE_INLINE_ATTR __attribute__((always_inline)) +#else + +#define INLINE_KEYWORD +#define FORCE_INLINE_ATTR + +#endif /* On MSVC qsort requires that functions passed into it use the __cdecl calling conversion(CC). diff --git a/lib/zstd/compress/zstd_opt.c b/lib/zstd/compress/zstd_opt.c index 04337050fe9a05..09483f518dc39e 100644 --- a/lib/zstd/compress/zstd_opt.c +++ b/lib/zstd/compress/zstd_opt.c @@ -8,6 +8,18 @@ * You may select, at your option, one of the above-listed licenses. */ +/* + * Disable inlining for the optimal parser for the kernel build. + * It is unlikely to be used in the kernel, and where it is used + * latency shouldn't matter because it is very slow to begin with. + * We prefer a ~180KB binary size win over faster optimal parsing. + * + * TODO(https://github.com/facebook/zstd/issues/2862): + * Improve the code size of the optimal parser in general, so we + * don't need this hack for the kernel build. + */ +#define ZSTD_NO_INLINE 1 + #include "zstd_compress_internal.h" #include "hist.h" #include "zstd_opt.h" @@ -894,7 +906,7 @@ static void ZSTD_optLdm_processMatchCandidate(ZSTD_optLdm_t* optLdm, ZSTD_match_ */ U32 posOvershoot = currPosInBlock - optLdm->endPosInBlock; ZSTD_optLdm_skipRawSeqStoreBytes(&optLdm->seqStore, posOvershoot); - } + } ZSTD_opt_getNextMatchAndUpdateSeqStore(optLdm, currPosInBlock, remainingBytes); } ZSTD_optLdm_maybeAddMatch(matches, nbMatches, optLdm, currPosInBlock); From 6e7f5882a9b52f9449f681273cef9336d99a1c11 Mon Sep 17 00:00:00 2001 From: Nick Terrell Date: Tue, 16 Nov 2021 15:11:39 -0800 Subject: [PATCH 3/3] lib: zstd: Don't add -O3 to cflags After the update to zstd-1.4.10 passing -O3 is no longer necessary to get good performance from zstd. Using the default optimization level -O2 is sufficient to get good performance. This fixes the reported parisc -Wframe-larger-than=1536 errors [0]. The gcc-8-hppa-linux-gnu compiler performed very poorly with -O3, generating stacks that are ~3KB. With -O2 these same functions generate stacks in the ~300B range, completely fixing the problem. Additionally, this improves the reported code bloat [1]. With gcc-11 bloat-o-meter shows an 80KB code size improvement: ``` > ../scripts/bloat-o-meter vmlinux.old vmlinux add/remove: 31/8 grow/shrink: 24/155 up/down: 25734/-107924 (-82190) Total: Before=6418562, After=6336372, chg -1.28% ``` Compared to before the zstd-1.4.10 update we see a total code size regression of 105KB, down from 374KB at v5.16-rc1: ``` > ../scripts/bloat-o-meter vmlinux.old vmlinux add/remove: 292/62 grow/shrink: 56/88 up/down: 235009/-127487 (107522) Total: Before=6228850, After=6336372, chg +1.73% ``` [0] https://lkml.org/lkml/2021/11/15/710 [1] https://lkml.org/lkml/2021/11/14/189 Reported-by: Geert Uytterhoeven Signed-off-by: Nick Terrell --- lib/zstd/Makefile | 2 -- 1 file changed, 2 deletions(-) diff --git a/lib/zstd/Makefile b/lib/zstd/Makefile index 65218ec5b8f2a4..fc45339fc3a365 100644 --- a/lib/zstd/Makefile +++ b/lib/zstd/Makefile @@ -11,8 +11,6 @@ obj-$(CONFIG_ZSTD_COMPRESS) += zstd_compress.o obj-$(CONFIG_ZSTD_DECOMPRESS) += zstd_decompress.o -ccflags-y += -O3 - zstd_compress-y := \ zstd_compress_module.o \ common/debug.o \