Merge pull request #3374 from giuseppe/cgroups

cgroups: add initial support for cgroups v2

1 files changed, 112 insertions, 0 deletions

diff --git a/pkg/cgroups/cpu.go b/pkg/cgroups/cpu.go
new file mode 100644
index 000000000..3f969fd3c
--- /dev/null
+++ b/pkg/cgroups/cpu.go
@@ -0,0 +1,112 @@
+package cgroups
+
+import (
+	"fmt"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"strconv"
+	"strings"
+
+	spec "github.com/opencontainers/runtime-spec/specs-go"
+	"github.com/pkg/errors"
+)
+
+type cpuHandler struct {
+}
+
+func getCPUHandler() *cpuHandler {
+	return &cpuHandler{}
+}
+
+func cleanString(s string) string {
+	return strings.Trim(s, "\n")
+}
+
+func readAcct(ctr *CgroupControl, name string) (uint64, error) {
+	p := filepath.Join(ctr.getCgroupv1Path(CPUAcct), name)
+	return readFileAsUint64(p)
+}
+
+func readAcctList(ctr *CgroupControl, name string) ([]uint64, error) {
+	var r []uint64
+
+	p := filepath.Join(ctr.getCgroupv1Path(CPUAcct), name)
+	data, err := ioutil.ReadFile(p)
+	if err != nil {
+		return nil, errors.Wrapf(err, "reading %s", p)
+	}
+	for _, s := range strings.Split(string(data), " ") {
+		s = cleanString(s)
+		if s == "" {
+			break
+		}
+		v, err := strconv.ParseUint(s, 10, 0)
+		if err != nil {
+			return nil, errors.Wrapf(err, "parsing %s", s)
+		}
+		r = append(r, v)
+	}
+	return r, nil
+}
+
+// Apply set the specified constraints
+func (c *cpuHandler) Apply(ctr *CgroupControl, res *spec.LinuxResources) error {
+	if res.CPU == nil {
+		return nil
+	}
+	return fmt.Errorf("cpu apply not implemented yet")
+}
+
+// Create the cgroup
+func (c *cpuHandler) Create(ctr *CgroupControl) (bool, error) {
+	if ctr.cgroup2 {
+		return false, fmt.Errorf("cpu create not implemented for cgroup v2")
+	}
+	return ctr.createCgroupDirectory(CPU)
+}
+
+// Destroy the cgroup
+func (c *cpuHandler) Destroy(ctr *CgroupControl) error {
+	return os.Remove(ctr.getCgroupv1Path(CPU))
+}
+
+// Stat fills a metrics structure with usage stats for the controller
+func (c *cpuHandler) Stat(ctr *CgroupControl, m *Metrics) error {
+	var err error
+	usage := CPUUsage{}
+	if ctr.cgroup2 {
+		values, err := readCgroup2MapFile(ctr, "cpu.stat")
+		if err != nil {
+			return err
+		}
+		if val, found := values["usage_usec"]; found {
+			usage.Kernel, err = strconv.ParseUint(cleanString(val[0]), 10, 0)
+			if err != nil {
+				return err
+			}
+		}
+		if val, found := values["system_usec"]; found {
+			usage.Total, err = strconv.ParseUint(cleanString(val[0]), 10, 0)
+			if err != nil {
+				return err
+			}
+		}
+		// FIXME: How to read usage.PerCPU?
+	} else {
+		usage.Total, err = readAcct(ctr, "cpuacct.usage")
+		if err != nil {
+			return err
+		}
+		usage.Kernel, err = readAcct(ctr, "cpuacct.usage_sys")
+		if err != nil {
+			return err
+		}
+		usage.PerCPU, err = readAcctList(ctr, "cpuacct.usage_percpu")
+		if err != nil {
+			return err
+		}
+	}
+	m.CPU = CPUMetrics{Usage: usage}
+	return nil
+}