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sched_getaffinity does not return number of online CPUs #2805

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merged 1 commit into from
Feb 17, 2021
Merged

sched_getaffinity does not return number of online CPUs #2805

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51 changes: 5 additions & 46 deletions container/libcontainer/handler.go
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Original file line number Diff line number Diff line change
Expand Up @@ -29,14 +29,13 @@ import (
"strings"
"time"

"github.com/google/cadvisor/container"
info "github.com/google/cadvisor/info/v1"
"golang.org/x/sys/unix"

"github.com/opencontainers/runc/libcontainer"
"github.com/opencontainers/runc/libcontainer/cgroups"
fs2 "github.com/opencontainers/runc/libcontainer/cgroups/fs2"
"github.com/opencontainers/runc/libcontainer/cgroups/fs2"
"k8s.io/klog/v2"

"github.com/google/cadvisor/container"
info "github.com/google/cadvisor/info/v1"
)

var (
Expand Down Expand Up @@ -758,16 +757,6 @@ func (h *Handler) GetProcesses() ([]int, error) {
return pids, nil
}

func minUint32(x, y uint32) uint32 {
if x < y {
return x
}
return y
}

// var to allow unit tests to stub it out
var numCpusFunc = getNumberOnlineCPUs

// Convert libcontainer stats to info.ContainerStats.
func setCPUStats(s *cgroups.Stats, ret *info.ContainerStats, withPerCPU bool) {
ret.Cpu.Usage.User = s.CpuStats.CpuUsage.UsageInUsermode
Expand All @@ -785,37 +774,7 @@ func setCPUStats(s *cgroups.Stats, ret *info.ContainerStats, withPerCPU bool) {
// cpuacct subsystem.
return
}

numPossible := uint32(len(s.CpuStats.CpuUsage.PercpuUsage))
// Note that as of https://patchwork.kernel.org/patch/8607101/ (kernel v4.7),
// the percpu usage information includes extra zero values for all additional
// possible CPUs. This is to allow statistic collection after CPU-hotplug.
// We intentionally ignore these extra zeroes.
numActual, err := numCpusFunc()
if err != nil {
klog.Errorf("unable to determine number of actual cpus; defaulting to maximum possible number: errno %v", err)
numActual = numPossible
}
if numActual > numPossible {
// The real number of cores should never be greater than the number of
// datapoints reported in cpu usage.
klog.Errorf("PercpuUsage had %v cpus, but the actual number is %v; ignoring extra CPUs", numPossible, numActual)
}
numActual = minUint32(numPossible, numActual)
ret.Cpu.Usage.PerCpu = make([]uint64, numActual)

for i := uint32(0); i < numActual; i++ {
ret.Cpu.Usage.PerCpu[i] = s.CpuStats.CpuUsage.PercpuUsage[i]
}

}

func getNumberOnlineCPUs() (uint32, error) {
var availableCPUs unix.CPUSet
if err := unix.SchedGetaffinity(0, &availableCPUs); err != nil {
return 0, err
}
return uint32(availableCPUs.Count()), nil
ret.Cpu.Usage.PerCpu = s.CpuStats.CpuUsage.PercpuUsage
}

func setDiskIoStats(s *cgroups.Stats, ret *info.ContainerStats) {
Expand Down
15 changes: 4 additions & 11 deletions container/libcontainer/handler_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -96,18 +96,11 @@ const nanosecondsInSeconds = 1000000000
// https://github.com/containerd/cgroups/pull/12
const clockTicks = 100

func TestMorePossibleCPUs(t *testing.T) {
realNumCPUs := uint32(8)
numCpusFunc = func() (uint32, error) {
return realNumCPUs, nil
}
possibleCPUs := uint32(31)

perCPUUsage := make([]uint64, possibleCPUs)
for i := uint32(0); i < realNumCPUs; i++ {
func TestSetCPUStats(t *testing.T) {
perCPUUsage := make([]uint64, 31)
for i := uint32(0); i < 31; i++ {
perCPUUsage[i] = 8562955455524
}

s := &cgroups.Stats{
CpuStats: cgroups.CpuStats{
CpuUsage: cgroups.CpuUsage{
Expand All @@ -124,7 +117,7 @@ func TestMorePossibleCPUs(t *testing.T) {
expected := info.ContainerStats{
Cpu: info.CpuStats{
Usage: info.CpuUsage{
PerCpu: perCPUUsage[0:realNumCPUs],
PerCpu: perCPUUsage,
User: s.CpuStats.CpuUsage.UsageInUsermode,
System: s.CpuStats.CpuUsage.UsageInKernelmode,
Total: 33802947350272,
Expand Down