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libct/cg: lazy init for HugePageSizes

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I have noticed that libct/cg/fs allocates 8K during init on every runc
execution:

> init github.com/opencontainers/runc/libcontainer/cgroups/fs @1.5 ms, 0.028 ms clock, 8512 bytes, 13 allocs

Apparently this is caused by global HugePageSizes variable init, which
is only used from GetStats (i.e. it is never used by runc itself).

Remove it, and use HugePageSizes() directly instead. Make it init-once,
so that GetStats (which, I guess, is periodically called by kubernetes)
does not re-read huge page sizes over and over.

This also removes 12 allocs and 8K from libct/cg/fs init section:

> $ time GODEBUG=inittrace=1 ./runc --help 2>&1 | grep cgroups/fs
> init github.com/opencontainers/runc/libcontainer/cgroups/fs @1.5 ms, 0.003 ms clock, 16 bytes, 1 allocs

Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
This commit is contained in:
Kir Kolyshkin
2021-10-05 17:18:03 -07:00
parent a4d4c4dd9f
commit 39d4c8d5f9
6 changed files with 45 additions and 52 deletions
Download Patch File Download Diff File Expand all files Collapse all files
libcontainer/cgroups/fs/fs.go
+16 -19
View File
@@ -13,25 +13,22 @@ import (
"github.com/opencontainers/runc/libcontainer/configs"
)
var (
subsystems = []subsystem{
&CpusetGroup{},
&DevicesGroup{},
&MemoryGroup{},
&CpuGroup{},
&CpuacctGroup{},
&PidsGroup{},
&BlkioGroup{},
&HugetlbGroup{},
&NetClsGroup{},
&NetPrioGroup{},
&PerfEventGroup{},
&FreezerGroup{},
&RdmaGroup{},
&NameGroup{GroupName: "name=systemd", Join: true},
}
HugePageSizes = cgroups.HugePageSizes()
)
var subsystems = []subsystem{
&CpusetGroup{},
&DevicesGroup{},
&MemoryGroup{},
&CpuGroup{},
&CpuacctGroup{},
&PidsGroup{},
&BlkioGroup{},
&HugetlbGroup{},
&NetClsGroup{},
&NetPrioGroup{},
&PerfEventGroup{},
&FreezerGroup{},
&RdmaGroup{},
&NameGroup{GroupName: "name=systemd", Join: true},
}
var errSubsystemDoesNotExist = errors.New("cgroup: subsystem does not exist")
libcontainer/cgroups/fs/hugetlb.go
+2 -2
View File
@@ -29,11 +29,11 @@ func (s *HugetlbGroup) Set(path string, r *configs.Resources) error {
}
func (s *HugetlbGroup) GetStats(path string, stats *cgroups.Stats) error {
hugetlbStats := cgroups.HugetlbStats{}
if !cgroups.PathExists(path) {
return nil
}
for _, pageSize := range HugePageSizes {
hugetlbStats := cgroups.HugetlbStats{}
for _, pageSize := range cgroups.HugePageSizes() {
usage := "hugetlb." + pageSize + ".usage_in_bytes"
value, err := fscommon.GetCgroupParamUint(path, usage)
if err != nil {
libcontainer/cgroups/fs/hugetlb_test.go
+7 -7
View File
@@ -31,14 +31,14 @@ func TestHugetlbSetHugetlb(t *testing.T) {
hugetlbAfter = 512
)
for _, pageSize := range HugePageSizes {
for _, pageSize := range cgroups.HugePageSizes() {
writeFileContents(t, path, map[string]string{
fmt.Sprintf(limit, pageSize): strconv.Itoa(hugetlbBefore),
})
}
r := &configs.Resources{}
for _, pageSize := range HugePageSizes {
for _, pageSize := range cgroups.HugePageSizes() {
r.HugetlbLimit = []*configs.HugepageLimit{
{
Pagesize: pageSize,
@@ -51,7 +51,7 @@ func TestHugetlbSetHugetlb(t *testing.T) {
}
}
for _, pageSize := range HugePageSizes {
for _, pageSize := range cgroups.HugePageSizes() {
limit := fmt.Sprintf(limit, pageSize)
value, err := fscommon.GetCgroupParamUint(path, limit)
if err != nil {
@@ -65,7 +65,7 @@ func TestHugetlbSetHugetlb(t *testing.T) {
func TestHugetlbStats(t *testing.T) {
path := tempDir(t, "hugetlb")
for _, pageSize := range HugePageSizes {
for _, pageSize := range cgroups.HugePageSizes() {
writeFileContents(t, path, map[string]string{
fmt.Sprintf(usage, pageSize): hugetlbUsageContents,
fmt.Sprintf(maxUsage, pageSize): hugetlbMaxUsageContents,
@@ -80,7 +80,7 @@ func TestHugetlbStats(t *testing.T) {
t.Fatal(err)
}
expectedStats := cgroups.HugetlbStats{Usage: 128, MaxUsage: 256, Failcnt: 100}
for _, pageSize := range HugePageSizes {
for _, pageSize := range cgroups.HugePageSizes() {
expectHugetlbStatEquals(t, expectedStats, actualStats.HugetlbStats[pageSize])
}
}
@@ -101,7 +101,7 @@ func TestHugetlbStatsNoUsageFile(t *testing.T) {
func TestHugetlbStatsNoMaxUsageFile(t *testing.T) {
path := tempDir(t, "hugetlb")
for _, pageSize := range HugePageSizes {
for _, pageSize := range cgroups.HugePageSizes() {
writeFileContents(t, path, map[string]string{
fmt.Sprintf(usage, pageSize): hugetlbUsageContents,
})
@@ -117,7 +117,7 @@ func TestHugetlbStatsNoMaxUsageFile(t *testing.T) {
func TestHugetlbStatsBadUsageFile(t *testing.T) {
path := tempDir(t, "hugetlb")
for _, pageSize := range HugePageSizes {
for _, pageSize := range cgroups.HugePageSizes() {
writeFileContents(t, path, map[string]string{
fmt.Sprintf(usage, pageSize): "bad",
maxUsage: hugetlbMaxUsageContents,
libcontainer/cgroups/fs2/hugetlb.go
+1 -3
View File
@@ -26,10 +26,8 @@ func setHugeTlb(dirPath string, r *configs.Resources) error {
}
func statHugeTlb(dirPath string, stats *cgroups.Stats) error {
hugePageSizes := cgroups.HugePageSizes()
hugetlbStats := cgroups.HugetlbStats{}
for _, pagesize := range hugePageSizes {
for _, pagesize := range cgroups.HugePageSizes() {
value, err := fscommon.GetCgroupParamUint(dirPath, "hugetlb."+pagesize+".current")
if err != nil {
return err
libcontainer/cgroups/utils.go
+19 -11
View File
@@ -302,18 +302,26 @@ func RemovePaths(paths map[string]string) (err error) {
return fmt.Errorf("Failed to remove paths: %v", paths)
}
func HugePageSizes() []string {
dir, err := os.OpenFile("/sys/kernel/mm/hugepages", unix.O_DIRECTORY|unix.O_RDONLY, 0)
if err != nil {
return nil
}
files, err := dir.Readdirnames(0)
dir.Close()
if err != nil {
return nil
}
var (
hugePageSizes []string
initHPSOnce sync.Once
)
func HugePageSizes() []string {
initHPSOnce.Do(func() {
dir, err := os.OpenFile("/sys/kernel/mm/hugepages", unix.O_DIRECTORY|unix.O_RDONLY, 0)
if err != nil {
return
}
files, err := dir.Readdirnames(0)
dir.Close()
if err != nil {
return
}
hugePageSizes, _ = getHugePageSizeFromFilenames(files)
})
hugePageSizes, _ := getHugePageSizeFromFilenames(files)
return hugePageSizes
}
libcontainer/cgroups/utils_test.go
-10
View File
@@ -448,16 +448,6 @@ func TestFindCgroupMountpointAndRoot(t *testing.T) {
}
}
func BenchmarkHugePageSizes(b *testing.B) {
var output []string
for i := 0; i < b.N; i++ {
output = HugePageSizes()
}
if len(output) == 0 {
b.Fatal("unexpected results")
}
}
func BenchmarkGetHugePageSizeImpl(b *testing.B) {
var (
input = []string{"hugepages-1048576kB", "hugepages-2048kB", "hugepages-32768kB", "hugepages-64kB"}