Add cgroup2 hugetlb failcnt metric

cgroup2/hugetlbv2_test.go

@@ -19,6 +19,7 @@ package cgroup2
 import (
 	"fmt"
 	"os"
+	"strconv"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -46,6 +47,8 @@ func TestCgroupv2HugetlbStats(t *testing.T) {
 	for _, entry := range stats.Hugetlb {
 		if entry.Pagesize == "2MB" {
 			assert.Equal(t, uint64(1073741824), entry.Max)
+			checkFileContent(t, c.path, "hugetlb."+entry.Pagesize+".current", strconv.FormatUint(entry.Current, 10))
+			checkFileContent(t, c.path, "hugetlb."+entry.Pagesize+".events", "max "+strconv.FormatUint(entry.Failcnt, 10))
 			break
 		}
 	}

cgroup2/stats/metrics.pb.txt

@@ -640,6 +640,13 @@ file {
       type: TYPE_STRING
       json_name: "pagesize"
     }
+    field {
+      name: "failcnt"
+      number: 4
+      label: LABEL_OPTIONAL
+      type: TYPE_UINT64
+      json_name: "failcnt"
+    }
   }
   message_type {
     name: "NetworkStat"

cgroup2/stats/metrics.proto

@@ -122,6 +122,7 @@ message HugeTlbStat {
 	uint64 current = 1;
 	uint64 max = 2;
 	string pagesize = 3;
+	uint64 failcnt = 4;
 }
 
 message NetworkStat {

cgroup2/utils.go

@@ -394,6 +394,7 @@ func readHugeTlbStats(path string) []*stats.HugeTlbStat {
 			Max:      getStatFileContentUint64(filepath.Join(path, "hugetlb."+pagesize+".max")),
 			Current:  getStatFileContentUint64(filepath.Join(path, "hugetlb."+pagesize+".current")),
 			Pagesize: pagesize,
+			Failcnt:  getStatFileContentUint64(filepath.Join(path, "hugetlb."+pagesize+".events")),
 		}
 	}
 	return usage