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package fs
import (
"bufio"
"errors"
"fmt"
"os"
"strconv"
"github.com/opencontainers/cgroups"
"github.com/opencontainers/cgroups/fscommon"
"golang.org/x/sys/unix"
)
type CpuGroup struct{}
func (s *CpuGroup) Name() string {
return "cpu"
}
func (s *CpuGroup) Apply(path string, r *cgroups.Resources, pid int) error {
if err := os.MkdirAll(path, 0o755); err != nil {
return err
}
// We should set the real-Time group scheduling settings before moving
// in the process because if the process is already in SCHED_RR mode
// and no RT bandwidth is set, adding it will fail.
if err := s.SetRtSched(path, r); err != nil {
return err
}
// Since we are not using apply(), we need to place the pid
// into the procs file.
return cgroups.WriteCgroupProc(path, pid)
}
func (s *CpuGroup) SetRtSched(path string, r *cgroups.Resources) error {
var period string
if r.CpuRtPeriod != 0 {
period = strconv.FormatUint(r.CpuRtPeriod, 10)
if err := cgroups.WriteFile(path, "cpu.rt_period_us", period); err != nil {
// The values of cpu.rt_period_us and cpu.rt_runtime_us
// are inter-dependent and need to be set in a proper order.
// If the kernel rejects the new period value with EINVAL
// and the new runtime value is also being set, let's
// ignore the error for now and retry later.
if !errors.Is(err, unix.EINVAL) || r.CpuRtRuntime == 0 {
return err
}
} else {
period = ""
}
}
if r.CpuRtRuntime != 0 {
if err := cgroups.WriteFile(path, "cpu.rt_runtime_us", strconv.FormatInt(r.CpuRtRuntime, 10)); err != nil {
return err
}
if period != "" {
if err := cgroups.WriteFile(path, "cpu.rt_period_us", period); err != nil {
return err
}
}
}
return nil
}
func (s *CpuGroup) Set(path string, r *cgroups.Resources) error {
if r.CpuShares != 0 {
shares := r.CpuShares
if err := cgroups.WriteFile(path, "cpu.shares", strconv.FormatUint(shares, 10)); err != nil {
return err
}
// read it back
sharesRead, err := fscommon.GetCgroupParamUint(path, "cpu.shares")
if err != nil {
return err
}
// ... and check
if shares > sharesRead {
return fmt.Errorf("the maximum allowed cpu-shares is %d", sharesRead)
} else if shares < sharesRead {
return fmt.Errorf("the minimum allowed cpu-shares is %d", sharesRead)
}
}
var period string
if r.CpuPeriod != 0 {
period = strconv.FormatUint(r.CpuPeriod, 10)
if err := cgroups.WriteFile(path, "cpu.cfs_period_us", period); err != nil {
// Sometimes when the period to be set is smaller
// than the current one, it is rejected by the kernel
// (EINVAL) as old_quota/new_period exceeds the parent
// cgroup quota limit. If this happens and the quota is
// going to be set, ignore the error for now and retry
// after setting the quota.
if !errors.Is(err, unix.EINVAL) || r.CpuQuota == 0 {
return err
}
} else {
period = ""
}
}
var burst string
if r.CpuBurst != nil {
burst = strconv.FormatUint(*r.CpuBurst, 10)
if err := cgroups.WriteFile(path, "cpu.cfs_burst_us", burst); err != nil {
if errors.Is(err, unix.ENOENT) {
// If CPU burst knob is not available (e.g.
// older kernel), ignore it.
burst = ""
} else {
// Sometimes when the burst to be set is larger
// than the current one, it is rejected by the kernel
// (EINVAL) as old_quota/new_burst exceeds the parent
// cgroup quota limit. If this happens and the quota is
// going to be set, ignore the error for now and retry
// after setting the quota.
if !errors.Is(err, unix.EINVAL) || r.CpuQuota == 0 {
return err
}
}
} else {
burst = ""
}
}
if r.CpuQuota != 0 {
if err := cgroups.WriteFile(path, "cpu.cfs_quota_us", strconv.FormatInt(r.CpuQuota, 10)); err != nil {
return err
}
if period != "" {
if err := cgroups.WriteFile(path, "cpu.cfs_period_us", period); err != nil {
return err
}
}
if burst != "" {
if err := cgroups.WriteFile(path, "cpu.cfs_burst_us", burst); err != nil {
return err
}
}
}
if r.CPUIdle != nil {
idle := strconv.FormatInt(*r.CPUIdle, 10)
if err := cgroups.WriteFile(path, "cpu.idle", idle); err != nil {
return err
}
}
return s.SetRtSched(path, r)
}
func (s *CpuGroup) GetStats(path string, stats *cgroups.Stats) error {
const file = "cpu.stat"
f, err := cgroups.OpenFile(path, file, os.O_RDONLY)
if err != nil {
if os.IsNotExist(err) {
return nil
}
return err
}
defer f.Close()
sc := bufio.NewScanner(f)
for sc.Scan() {
t, v, err := fscommon.ParseKeyValue(sc.Text())
if err != nil {
return &parseError{Path: path, File: file, Err: err}
}
switch t {
case "nr_periods":
stats.CpuStats.ThrottlingData.Periods = v
case "nr_throttled":
stats.CpuStats.ThrottlingData.ThrottledPeriods = v
case "throttled_time":
stats.CpuStats.ThrottlingData.ThrottledTime = v
}
}
return nil
}
|
