Remove sampling from libcontainer CPU stats.
Sampling should be done by higher layer in configurable intervals. This change removes the percentage stat as sampling is required for this. Docker-DCO-1.1-Signed-off-by: Victor Marmol <vmarmol@google.com> (github: vmarmol)
This commit is contained in:
Victor Marmol
parent
55430d0db7
commit
2636848328
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@ -1,26 +1,22 @@
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package fs
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import (
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"bufio"
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"fmt"
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"io/ioutil"
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"os"
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"path/filepath"
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"runtime"
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"strconv"
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"strings"
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"time"
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"github.com/docker/libcontainer/cgroups"
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"github.com/docker/libcontainer/system"
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)
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var (
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cpuCount = uint64(runtime.NumCPU())
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clockTicks = uint64(system.GetClockTicks())
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const (
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cgroupCpuacctStat = "cpuacct.stat"
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nanosecondsInSecond = 1000000000
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)
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const nanosecondsInSecond = 1000000000
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var clockTicks = uint64(system.GetClockTicks())
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type CpuacctGroup struct {
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}
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@ -39,103 +35,53 @@ func (s *CpuacctGroup) Remove(d *data) error {
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}
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func (s *CpuacctGroup) GetStats(path string, stats *cgroups.Stats) error {
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var (
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err error
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startCpu, lastCpu, startSystem, lastSystem, startUsage, lastUsage, kernelModeUsage, userModeUsage, percentage uint64
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)
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if kernelModeUsage, userModeUsage, err = getCpuUsage(path); err != nil {
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return err
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}
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startCpu = kernelModeUsage + userModeUsage
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if startSystem, err = getSystemCpuUsage(); err != nil {
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return err
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}
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startUsageTime := time.Now()
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if startUsage, err = getCgroupParamInt(path, "cpuacct.usage"); err != nil {
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return err
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}
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// sample for 100ms
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time.Sleep(1000 * time.Millisecond)
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if kernelModeUsage, userModeUsage, err = getCpuUsage(path); err != nil {
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return err
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}
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lastCpu = kernelModeUsage + userModeUsage
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if lastSystem, err = getSystemCpuUsage(); err != nil {
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return err
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}
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usageSampleDuration := time.Since(startUsageTime)
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if lastUsage, err = getCgroupParamInt(path, "cpuacct.usage"); err != nil {
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userModeUsage, kernelModeUsage, err := getCpuUsageBreakdown(path)
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if err != nil {
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return err
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}
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var (
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deltaProc = lastCpu - startCpu
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deltaSystem = lastSystem - startSystem
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deltaUsage = lastUsage - startUsage
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)
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if deltaSystem > 0.0 {
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percentage = uint64((float64(deltaProc) / float64(deltaSystem)) * float64(clockTicks*cpuCount))
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totalUsage, err := getCgroupParamInt(path, "cpuacct.usage")
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if err != nil {
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return err
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}
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// NOTE: a percentage over 100% is valid for POSIX because that means the
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// processes is using multiple cores
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stats.CpuStats.CpuUsage.PercentUsage = percentage
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// Delta usage is in nanoseconds of CPU time so get the usage (in cores) over the sample time.
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stats.CpuStats.CpuUsage.CurrentUsage = deltaUsage / uint64(usageSampleDuration.Nanoseconds())
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percpuUsage, err := getPercpuUsage(path)
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if err != nil {
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return err
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}
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stats.CpuStats.CpuUsage.TotalUsage = lastUsage
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stats.CpuStats.CpuUsage.TotalUsage = totalUsage
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stats.CpuStats.CpuUsage.PercpuUsage = percpuUsage
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stats.CpuStats.CpuUsage.UsageInKernelmode = (kernelModeUsage * nanosecondsInSecond) / clockTicks
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stats.CpuStats.CpuUsage.UsageInUsermode = (userModeUsage * nanosecondsInSecond) / clockTicks
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stats.CpuStats.CpuUsage.UsageInUsermode = userModeUsage
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stats.CpuStats.CpuUsage.UsageInKernelmode = kernelModeUsage
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return nil
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}
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// TODO(vmarmol): Use cgroups stats.
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func getSystemCpuUsage() (uint64, error) {
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f, err := os.Open("/proc/stat")
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if err != nil {
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return 0, err
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}
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defer f.Close()
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sc := bufio.NewScanner(f)
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for sc.Scan() {
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parts := strings.Fields(sc.Text())
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switch parts[0] {
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case "cpu":
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if len(parts) < 8 {
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return 0, fmt.Errorf("invalid number of cpu fields")
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}
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var total uint64
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for _, i := range parts[1:8] {
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v, err := strconv.ParseUint(i, 10, 64)
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if err != nil {
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return 0.0, fmt.Errorf("Unable to convert value %s to int: %s", i, err)
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}
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total += v
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}
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return total, nil
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default:
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continue
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}
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}
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return 0, fmt.Errorf("invalid stat format")
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}
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func getCpuUsage(path string) (uint64, uint64, error) {
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kernelModeUsage := uint64(0)
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// Returns user and kernel usage breakdown in nanoseconds.
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func getCpuUsageBreakdown(path string) (uint64, uint64, error) {
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userModeUsage := uint64(0)
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data, err := ioutil.ReadFile(filepath.Join(path, "cpuacct.stat"))
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kernelModeUsage := uint64(0)
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const (
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userField = "user"
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systemField = "system"
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)
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// Expected format:
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// user <usage in ticks>
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// system <usage in ticks>
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data, err := ioutil.ReadFile(filepath.Join(path, cgroupCpuacctStat))
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if err != nil {
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return 0, 0, err
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}
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fields := strings.Fields(string(data))
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if len(fields) != 4 {
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return 0, 0, fmt.Errorf("Failure - %s is expected to have 4 fields", filepath.Join(path, "cpuacct.stat"))
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return 0, 0, fmt.Errorf("failure - %s is expected to have 4 fields", filepath.Join(path, cgroupCpuacctStat))
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}
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if fields[0] != userField {
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return 0, 0, fmt.Errorf("unexpected field %q in %q, expected %q", fields[0], cgroupCpuacctStat, userField)
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}
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if fields[2] != systemField {
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return 0, 0, fmt.Errorf("unexpected field %q in %q, expected %q", fields[2], cgroupCpuacctStat, systemField)
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}
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if userModeUsage, err = strconv.ParseUint(fields[1], 10, 64); err != nil {
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return 0, 0, err
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@ -144,7 +90,7 @@ func getCpuUsage(path string) (uint64, uint64, error) {
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return 0, 0, err
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}
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return kernelModeUsage, userModeUsage, nil
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return (userModeUsage * nanosecondsInSecond) / clockTicks, (kernelModeUsage * nanosecondsInSecond) / clockTicks, nil
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}
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func getPercpuUsage(path string) ([]uint64, error) {
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@ -9,17 +9,19 @@ type ThrottlingData struct {
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ThrottledTime uint64 `json:"throttled_time,omitempty"`
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}
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// All CPU stats are aggregate since container inception.
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type CpuUsage struct {
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// percentage of available CPUs currently being used.
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PercentUsage uint64 `json:"percent_usage,omitempty"`
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// nanoseconds of cpu time consumed over the last 100 ms.
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CurrentUsage uint64 `json:"current_usage,omitempty"`
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// total nanoseconds of cpu time consumed
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TotalUsage uint64 `json:"total_usage,omitempty"`
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// Total CPU time consumed.
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// Units: nanoseconds.
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TotalUsage uint64 `json:"total_usage,omitempty"`
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// Total CPU time consumed per core.
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// Units: nanoseconds.
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PercpuUsage []uint64 `json:"percpu_usage,omitempty"`
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// Time spent by tasks of the cgroup in kernel mode. Units: nanoseconds.
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// Time spent by tasks of the cgroup in kernel mode.
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// Units: nanoseconds.
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UsageInKernelmode uint64 `json:"usage_in_kernelmode"`
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// Time spent by tasks of the cgroup in user mode. Units: nanoseconds.
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// Time spent by tasks of the cgroup in user mode.
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// Units: nanoseconds.
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UsageInUsermode uint64 `json:"usage_in_usermode"`
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}
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