Added cgroups v2 CPU implementation.

cmd/cgroups-playground/main.go

@@ -17,10 +17,11 @@
 package main
 
 import (
-	"os"
-
 	"github.com/containerd/cgroups/v2"
+	stats2 "github.com/containerd/cgroups/v2/stats"
+	"github.com/opencontainers/runtime-spec/specs-go"
 	"github.com/sirupsen/logrus"
+	"os"
 )
 
 func main() {
@@ -54,5 +55,29 @@ func xmain() error {
 	for i, s := range subsystems {
 		logrus.Infof("Subsystem %d: %q", i, s.Name())
 	}
+
+	cpuCgroup, err := v2.NewCpu(unifiedMountpoint)
+	if err != nil {
+		return err
+	}
+	var period, shares uint64 = 1000, 5000
+	resources := specs.LinuxResources{
+		CPU: &specs.LinuxCPU{Period: &period, Shares: &shares},
+	}
+	err = cpuCgroup.Create(g, &resources)
+	if err != nil {
+		return err
+	}
+	stats := stats2.Metrics{
+		CPU: &stats2.CPUStat{
+			Usage: &stats2.CPUUsage{},
+		},
+	}
+	err = cpuCgroup.Stat(g, &stats)
+	if err != nil {
+		return err
+	}
+	logrus.Infof("CPU usage stats: usage in kernel mode - %d", stats.CPU.Usage.Kernel)
+
 	return nil
 }

v2/cpu.go

@@ -0,0 +1,123 @@
+/*
+   Copyright The containerd Authors.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package v2
+
+import (
+	"bufio"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"strconv"
+
+	statsv2 "github.com/containerd/cgroups/v2/stats"
+	specs "github.com/opencontainers/runtime-spec/specs-go"
+)
+
+func NewCpu(unifiedMountpoint string) (*cpuController, error) {
+	c := &cpuController{
+		unifiedMountpoint: unifiedMountpoint,
+	}
+
+	ok, err := c.Available("/")
+	if err != nil {
+		return nil, err
+	}
+	if !ok {
+		return nil, ErrCPUNotSupported
+	}
+	return c, nil
+}
+
+type cpuController struct {
+	unifiedMountpoint string
+}
+
+func (c *cpuController) Name() Name {
+	return Cpu
+}
+
+func (c *cpuController) path(g GroupPath) string {
+	return filepath.Join(c.unifiedMountpoint, string(g))
+}
+
+func (c *cpuController) Create(g GroupPath, resources *specs.LinuxResources) error {
+	if err := os.MkdirAll(c.path(g), defaultDirPerm); err != nil {
+		return err
+	}
+	if cpuShares := resources.CPU.Shares; cpuShares != nil {
+		// Converting cgroups configuration from v1 to v2
+		// more here https://github.com/containers/crun/blob/master/crun.1.md#cgroup-v2
+		convertedWeight := (1 + ((*cpuShares-2)*9999)/262142)
+		weight := []byte(strconv.FormatUint(convertedWeight, 10))
+		if err := ioutil.WriteFile(
+			filepath.Join(c.path(g), "cpu.weight"),
+			weight,
+			defaultFilePerm,
+		); err != nil {
+			return err
+		}
+	}
+
+	if cpuPeriod := resources.CPU.Period; cpuPeriod != nil {
+		max := []byte(strconv.FormatUint(*cpuPeriod, 10))
+		if err := ioutil.WriteFile(
+			filepath.Join(c.path(g), "cpu.max"),
+			max,
+			defaultFilePerm,
+		); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+func (c *cpuController) Update(g GroupPath, resources *specs.LinuxResources) error {
+	return c.Create(g, resources)
+}
+
+func (c *cpuController) Stat(g GroupPath, stats *statsv2.Metrics) error {
+	f, err := os.Open(filepath.Join(c.path(g), "cpu.stat"))
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+	// get or create the cpu field because cpuacct can also set values on this struct
+	sc := bufio.NewScanner(f)
+	for sc.Scan() {
+		if err := sc.Err(); err != nil {
+			return err
+		}
+		key, v, err := parseKV(sc.Text())
+		if err != nil {
+			return err
+		}
+		switch key {
+		case "usage_usec":
+			stats.CPU.Usage.Total = v
+		case "user_usec":
+			stats.CPU.Usage.User = v
+		case "system_usec":
+			stats.CPU.Usage.Kernel = v
+		}
+	}
+	return nil
+}
+
+func (c *cpuController) Available(g GroupPath) (bool, error) {
+	return available(c.unifiedMountpoint, g, Pids)
+}

v2/errors.go

@@ -28,6 +28,7 @@ var (
 	ErrFreezerNotSupported      = errors.New("cgroups: freezer cgroup (v2) not supported on this system")
 	ErrMemoryNotSupported       = errors.New("cgroups: memory cgroup (v2) not supported on this system")
 	ErrPidsNotSupported         = errors.New("cgroups: pids cgroup (v2) not supported on this system")
+	ErrCPUNotSupported          = errors.New("cgroups: cpu cgroup (v2) not supported on this system")
 	ErrCgroupDeleted            = errors.New("cgroups: cgroup deleted")
 	ErrNoCgroupMountDestination = errors.New("cgroups: cannot find cgroup mount destination")