adds cgroupsv2 support (#1283)

* adds cgroupv2 limits support
https://github.com/VictoriaMetrics/VictoriaMetrics/issues/1269

* small fix

* changes Atoi to ParseUint

lib/cgroup/cpu.go

@@ -1,6 +1,7 @@
 package cgroup
 
 import (
+	"fmt"
 	"io/ioutil"
 	"os"
 	"runtime"
@@ -41,20 +42,28 @@ func updateGOMAXPROCSToCPUQuota() {
 }
 
 func getCPUQuota() float64 {
-	quotaUS, err := getCPUStat("cpu.cfs_quota_us")
+	cpuQuota, err := getCPUStatGeneric()
 	if err != nil {
 		return 0
 	}
-	if quotaUS <= 0 {
+
+	if cpuQuota <= 0 {
 		// The quota isn't set. This may be the case in multilevel containers.
 		// See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/685#issuecomment-674423728
 		return getOnlineCPUCount()
 	}
-	periodUS, err := getCPUStat("cpu.cfs_period_us")
-	if err != nil {
-		return 0
+	return cpuQuota
+}
+
+func getCPUStatGeneric() (float64, error) {
+	quotaUS, err := getCPUStat("cpu.cfs_quota_us")
+	if err == nil {
+		periodUS, err := getCPUStat("cpu.cfs_period_us")
+		if err == nil {
+			return float64(quotaUS) / float64(periodUS), nil
+		}
 	}
-	return float64(quotaUS) / float64(periodUS)
+	return getCPUStatV2("/sys/fs/cgroup", "/proc/self/cgroup")
 }
 
 func getCPUStat(statName string) (int64, error) {
@@ -74,6 +83,35 @@ func getOnlineCPUCount() float64 {
 	return n
 }
 
+func getCPUStatV2(sysPrefix, cgroupPath string) (float64, error) {
+	data, err := getFileContents("cpu.max", sysPrefix, cgroupPath, "")
+	if err != nil {
+		return 0, err
+	}
+	return parseCPUMax(data)
+}
+
+// https://www.kernel.org/doc/html/latest/admin-guide/cgroup-v2.html#cpu
+func parseCPUMax(data string) (float64, error) {
+	data = strings.TrimRight(data, "\r\n")
+	bounds := strings.Split(data, " ")
+	if len(bounds) != 2 {
+		return 0, fmt.Errorf("unexpected count: %d, want quota and period, got: %s", len(bounds), data)
+	}
+	if bounds[0] == "max" {
+		return -1, nil
+	}
+	quota, err := strconv.ParseUint(bounds[0], 10, 64)
+	if err != nil {
+		return 0, err
+	}
+	period, err := strconv.ParseUint(bounds[1], 10, 64)
+	if err != nil {
+		return 0, err
+	}
+	return float64(quota) / float64(period), nil
+}
+
 func countCPUs(data string) int {
 	data = strings.TrimSpace(data)
 	n := 0

lib/cgroup/cpu_test.go

@@ -22,3 +22,17 @@ func TestCountCPUs(t *testing.T) {
 	f("0-3", 4)
 	f("0-6", 7)
 }
+
+func TestGetCPUStatV2(t *testing.T) {
+	f := func(sysPrefix, cgroupPath string, expectedCPU float64) {
+		t.Helper()
+		got, err := getCPUStatV2(sysPrefix, cgroupPath)
+		if err != nil {
+			t.Fatalf("unexpected error: %s, sysPrefix: %s, cgroupPath: %s", err, sysPrefix, cgroupPath)
+		}
+		if got != expectedCPU {
+			t.Fatalf("unexpected result from getCPUStatV2(%s, %s), got %f, want %f", sysPrefix, cgroupPath, got, expectedCPU)
+		}
+	}
+	f("testdata/cgroup", "testdata/self/cgroupv2", 2)
+}

lib/cgroup/mem.go

@@ -13,12 +13,22 @@ func GetMemoryLimit() int64 {
 	// This should properly determine the limit inside lxc container.
 	// See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/84
 	n, err := getMemStat("memory.limit_in_bytes")
+	if err == nil {
+		return n
+	}
+	// https: //www.kernel.org/doc/html/latest/admin-guide/cgroup-v2.html#memory-interface-files
+	n, err = getMemStatV2()
 	if err != nil {
 		return 0
 	}
+
 	return n
 }
 
+func getMemStatV2() (int64, error) {
+	return getStatGeneric("memory.max", "/sys/fs/cgroup", "/proc/self/cgroup", "")
+}
+
 func getMemStat(statName string) (int64, error) {
 	return getStatGeneric(statName, "/sys/fs/cgroup/memory", "/proc/self/cgroup", "memory")
 }

lib/cgroup/testdata/cgroup/cpu.max

@@ -0,0 +1 @@
+200000 100000

lib/cgroup/testdata/cgroup/memory.max

@@ -0,0 +1 @@
+523372036854771712

lib/cgroup/testdata/self/cgroupv2

@@ -0,0 +1 @@
+0::/

lib/cgroup/util.go

@@ -13,6 +13,7 @@ func getStatGeneric(statName, sysfsPrefix, cgroupPath, cgroupGrepLine string) (i
 	if err != nil {
 		return 0, err
 	}
+	data = strings.TrimRight(data, "\r\n")
 	n, err := strconv.ParseInt(data, 10, 64)
 	if err != nil {
 		return 0, err

lib/cgroup/util_test.go

@@ -21,6 +21,7 @@ func TestGetStatGenericSuccess(t *testing.T) {
 	f("cpu.cfs_period_us", "testdata/cgroup", "testdata/self/cgroup", "cpu,", 500000)
 	f("memory.limit_in_bytes", "testdata/", "testdata/self/cgroup", "memory", 9223372036854771712)
 	f("memory.limit_in_bytes", "testdata/cgroup", "testdata/self/cgroup", "memory", 523372036854771712)
+	f("memory.max", "testdata/cgroup", "testdata/self/cgroupv2", "", 523372036854771712)
 }
 
 func TestGetStatGenericFailure(t *testing.T) {
@@ -37,4 +38,5 @@ func TestGetStatGenericFailure(t *testing.T) {
 	f("cpu.cfs_quota_us", "testdata/", "testdata/missing_folder", "cpu,")
 	f("cpu.cfs_period_us", "testdata/", "testdata/missing_folder", "cpu,")
 	f("memory.limit_in_bytes", "testdata/", "testdata/none_existing_folder", "memory")
+	f("memory.max", "testdata/", "testdata/none_existing_folder", "")
 }