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Add initial support for rsvd accounting hugetlb cgroup #2360

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Add initial support for rsvd accounting hugetlb cgroup #2360

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32 changes: 29 additions & 3 deletions libcontainer/cgroups/fs/hugetlb.go
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Original file line number Diff line number Diff line change
Expand Up @@ -27,11 +27,30 @@ func (s *HugetlbGroup) Apply(d *cgroupData) error {
return nil
}

// HasReservationAccountingSupport checks if reservation accounting of huge pages in the hugetlb cgroup
// is supported. This is supported from linux 5.7
// https://www.kernel.org/doc/html/latest/admin-guide/cgroup-v1/hugetlb.html
func (s *HugetlbGroup) HasReservationAccountingSupport(path string) bool {
if len(HugePageSizes) == 0 {
return false
}
_, err := fscommon.ReadFile(path, strings.Join([]string{"hugetlb", HugePageSizes[0], "rsvd", "limit_in_bytes"}, "."))
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use cgroups.PathExists here

return err == nil
}

func (s *HugetlbGroup) Set(path string, cgroup *configs.Cgroup) error {
supportsReservationAccounting := s.HasReservationAccountingSupport(path)
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Not sure if this is the best way to check, or should we try to "cache" the value like we do with HugePageSizes?

for _, hugetlb := range cgroup.Resources.HugetlbLimit {
if err := fscommon.WriteFile(path, strings.Join([]string{"hugetlb", hugetlb.Pagesize, "limit_in_bytes"}, "."), strconv.FormatUint(hugetlb.Limit, 10)); err != nil {
return err
}

if !supportsReservationAccounting {
continue
}
if err := fscommon.WriteFile(path, strings.Join([]string{"hugetlb", hugetlb.Pagesize, "rsvd", "limit_in_bytes"}, "."), strconv.FormatUint(hugetlb.Limit, 10)); err != nil {
return err
}
}

return nil
Expand All @@ -43,22 +62,29 @@ func (s *HugetlbGroup) Remove(d *cgroupData) error {

func (s *HugetlbGroup) GetStats(path string, stats *cgroups.Stats) error {
hugetlbStats := cgroups.HugetlbStats{}
supportsReservationAccounting := s.HasReservationAccountingSupport(path)

for _, pageSize := range HugePageSizes {
usage := strings.Join([]string{"hugetlb", pageSize, "usage_in_bytes"}, ".")
filenamePrefix := strings.Join([]string{"hugetlb", pageSize}, ".")

if supportsReservationAccounting {
filenamePrefix += ".rsvd"
}
usage := fmt.Sprintf("%s.usage_in_bytes", filenamePrefix)
value, err := fscommon.GetCgroupParamUint(path, usage)
if err != nil {
return fmt.Errorf("failed to parse %s - %v", usage, err)
}
hugetlbStats.Usage = value

maxUsage := strings.Join([]string{"hugetlb", pageSize, "max_usage_in_bytes"}, ".")
maxUsage := fmt.Sprintf("%s.max_usage_in_bytes", filenamePrefix)
value, err = fscommon.GetCgroupParamUint(path, maxUsage)
if err != nil {
return fmt.Errorf("failed to parse %s - %v", maxUsage, err)
}
hugetlbStats.MaxUsage = value

failcnt := strings.Join([]string{"hugetlb", pageSize, "failcnt"}, ".")
failcnt := fmt.Sprintf("%s.failcnt", filenamePrefix)
value, err = fscommon.GetCgroupParamUint(path, failcnt)
if err != nil {
return fmt.Errorf("failed to parse %s - %v", failcnt, err)
Expand Down
57 changes: 57 additions & 0 deletions libcontainer/cgroups/fs/hugetlb_test.go
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Expand Up @@ -23,6 +23,11 @@ var (
limit = "hugetlb.%s.limit_in_bytes"
maxUsage = "hugetlb.%s.max_usage_in_bytes"
failcnt = "hugetlb.%s.failcnt"

rsvdUsage = "hugetlb.%s.rsvd.usage_in_bytes"
rsvdLimit = "hugetlb.%s.rsvd.limit_in_bytes"
rsvdMaxUsage = "hugetlb.%s.rsvd.max_usage_in_bytes"
rsvdFailcnt = "hugetlb.%s.rsvd.failcnt"
)

func TestHugetlbSetHugetlb(t *testing.T) {
Expand Down Expand Up @@ -65,6 +70,58 @@ func TestHugetlbSetHugetlb(t *testing.T) {
}
}

func TestHugetlbSetHugetlbWithReservedAccounting(t *testing.T) {
helper := NewCgroupTestUtil("hugetlb", t)
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shouldn't this test be skipped if !HasReservationAccountingSupport()?

defer helper.cleanup()

const (
hugetlbBefore = 256
hugetlbAfter = 512
)

for _, pageSize := range HugePageSizes {
helper.writeFileContents(map[string]string{
fmt.Sprintf(limit, pageSize): strconv.Itoa(hugetlbBefore),
})
helper.writeFileContents(map[string]string{
fmt.Sprintf(rsvdLimit, pageSize): strconv.Itoa(hugetlbBefore),
})
}

for _, pageSize := range HugePageSizes {
helper.CgroupData.config.Resources.HugetlbLimit = []*configs.HugepageLimit{
{
Pagesize: pageSize,
Limit: hugetlbAfter,
},
}
hugetlb := &HugetlbGroup{}
if err := hugetlb.Set(helper.CgroupPath, helper.CgroupData.config); err != nil {
t.Fatal(err)
}
}

for _, pageSize := range HugePageSizes {
limitFile := fmt.Sprintf(limit, pageSize)
value, err := fscommon.GetCgroupParamUint(helper.CgroupPath, limitFile)
if err != nil {
t.Fatalf("Failed to parse %s - %s", limitFile, err)
}
if value != hugetlbAfter {
t.Fatalf("Set hugetlb.limit_in_bytes failed. Expected: %v, Got: %v", hugetlbAfter, value)
}

rsvdLimitFile := fmt.Sprintf(rsvdLimit, pageSize)
rsvdValue, err := fscommon.GetCgroupParamUint(helper.CgroupPath, rsvdLimitFile)
if err != nil {
t.Fatalf("Failed to parse %s - %s", rsvdLimitFile, err)
}
if rsvdValue != hugetlbAfter {
t.Fatalf("Set hugetlb.limit_in_bytes failed. Expected: %v, Got: %v", hugetlbAfter, rsvdValue)
}
}
}

func TestHugetlbStats(t *testing.T) {
helper := NewCgroupTestUtil("hugetlb", t)
defer helper.cleanup()
Expand Down
32 changes: 30 additions & 2 deletions libcontainer/cgroups/fs2/hugetlb.go
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Expand Up @@ -3,6 +3,7 @@
package fs2

import (
"fmt"
"io/ioutil"
"path/filepath"
"strconv"
Expand All @@ -19,14 +20,33 @@ func isHugeTlbSet(cgroup *configs.Cgroup) bool {
return len(cgroup.Resources.HugetlbLimit) > 0
}

// HasReservationAccountingSupport checks if reservation accounting of huge pages in the hugetlb cgroup
// is supported. This is supported from linux 5.7
// https://www.kernel.org/doc/html/latest/admin-guide/cgroup-v1/hugetlb.html
func HasReservationAccountingSupport(dirPath string) bool {
hugePageSizes, err := cgroups.GetHugePageSize()
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Yes, I think it makes sense to do this check once, using sync.Once.

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or not... since different cgroups can have different controls I guess...

if err != nil || len(hugePageSizes) == 0 {
return false
}
_, err = fscommon.ReadFile(dirPath, strings.Join([]string{"hugetlb", hugePageSizes[0], "rsvd", "max"}, "."))
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use cgroups.PathExists()

return err == nil
}

func setHugeTlb(dirPath string, cgroup *configs.Cgroup) error {
if !isHugeTlbSet(cgroup) {
return nil
}
supportsReservationAccounting := HasReservationAccountingSupport(dirPath)
for _, hugetlb := range cgroup.Resources.HugetlbLimit {
if err := fscommon.WriteFile(dirPath, strings.Join([]string{"hugetlb", hugetlb.Pagesize, "max"}, "."), strconv.FormatUint(hugetlb.Limit, 10)); err != nil {
return err
}
if !supportsReservationAccounting {
continue
}
if err := fscommon.WriteFile(dirPath, strings.Join([]string{"hugetlb", hugetlb.Pagesize, "rsvd", "max"}, "."), strconv.FormatUint(hugetlb.Limit, 10)); err != nil {
return err
}
}

return nil
Expand All @@ -39,15 +59,23 @@ func statHugeTlb(dirPath string, stats *cgroups.Stats) error {
}
hugetlbStats := cgroups.HugetlbStats{}

supportsReservationAccounting := HasReservationAccountingSupport(dirPath)

for _, pagesize := range hugePageSizes {
usage := strings.Join([]string{"hugetlb", pagesize, "current"}, ".")
filenamePrefix := strings.Join([]string{"hugetlb", pagesize}, ".")
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nit: maybe it would be better to have it as

filenamePrefix := "hugetlb."+pagesize

(for readability)


if supportsReservationAccounting {
filenamePrefix += ".rsvd"
}

usage := fmt.Sprintf("%s.current", filenamePrefix)
value, err := fscommon.GetCgroupParamUint(dirPath, usage)
if err != nil {
return errors.Wrapf(err, "failed to parse hugetlb.%s.current file", pagesize)
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The error message from GetCgroupParamUint already contain file name, so you can return the error as-is, no need to wrap it.

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also the error now returns the wrong file name in case supportsReservationAccounting is set

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Fixing this should be done as a separate first patch I think.

}
hugetlbStats.Usage = value

fileName := strings.Join([]string{"hugetlb", pagesize, "events"}, ".")
fileName := fmt.Sprintf("%s.events", filenamePrefix)
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nit: using fileName := filenamePrefix + ".events" would be faster

but either way is fine

filePath := filepath.Join(dirPath, fileName)
contents, err := ioutil.ReadFile(filePath)
if err != nil {
Expand Down