stats: add SystemUsage

Signed-off-by: Giuseppe Scrivano <gscrivan@redhat.com>

pkg/api/handlers/generic/containers_stats.go

@@ -64,6 +64,7 @@ func StatsContainer(w http.ResponseWriter, r *http.Request) {
 	var preCPUStats docker.CPUStats
 	if query.Stream {
 		preRead = time.Now()
+		systemUsage, _ := cgroups.GetSystemCPUUsage()
 		preCPUStats = docker.CPUStats{
 			CPUUsage: docker.CPUUsage{
 				TotalUsage:        stats.CPUNano,
@@ -71,7 +72,7 @@ func StatsContainer(w http.ResponseWriter, r *http.Request) {
 				UsageInKernelmode: stats.CPUSystemNano,
 				UsageInUsermode:   stats.CPUNano - stats.CPUSystemNano,
 			},
-			SystemUsage:    0,
+			SystemUsage:    systemUsage,
 			OnlineCPUs:     0,
 			ThrottlingData: docker.ThrottlingData{},
 		}
@@ -125,6 +126,8 @@ func StatsContainer(w http.ResponseWriter, r *http.Request) {
 			InstanceID: "",
 		}
 
+		systemUsage, _ := cgroups.GetSystemCPUUsage()
+
 		s := handlers.Stats{StatsJSON: docker.StatsJSON{
 			Stats: docker.Stats{
 				Read:    time.Now(),
@@ -150,7 +153,7 @@ func StatsContainer(w http.ResponseWriter, r *http.Request) {
 						UsageInKernelmode: cgroupStat.CPU.Usage.Kernel,
 						UsageInUsermode:   cgroupStat.CPU.Usage.Total - cgroupStat.CPU.Usage.Kernel,
 					},
-					SystemUsage: 0,
+					SystemUsage: systemUsage,
 					OnlineCPUs:  uint32(len(cgroupStat.CPU.Usage.PerCPU)),
 					ThrottlingData: docker.ThrottlingData{
 						Periods:          0,

pkg/cgroups/cgroups.go

@@ -536,15 +536,14 @@ func (c *CgroupControl) Stat() (*Metrics, error) {
 	return &m, nil
 }
 
-func readCgroup2MapFile(ctr *CgroupControl, name string) (map[string][]string, error) {
+func readCgroup2MapPath(path string) (map[string][]string, error) {
 	ret := map[string][]string{}
-	p := filepath.Join(cgroupRoot, ctr.path, name)
-	f, err := os.Open(p)
+	f, err := os.Open(path)
 	if err != nil {
 		if os.IsNotExist(err) {
 			return ret, nil
 		}
-		return nil, errors.Wrapf(err, "open file %s", p)
+		return nil, errors.Wrapf(err, "open file %s", path)
 	}
 	defer f.Close()
 	scanner := bufio.NewScanner(f)
@@ -557,7 +556,13 @@ func readCgroup2MapFile(ctr *CgroupControl, name string) (map[string][]string, e
 		ret[parts[0]] = parts[1:]
 	}
 	if err := scanner.Err(); err != nil {
-		return nil, errors.Wrapf(err, "parsing file %s", p)
+		return nil, errors.Wrapf(err, "parsing file %s", path)
 	}
 	return ret, nil
 }
+
+func readCgroup2MapFile(ctr *CgroupControl, name string) (map[string][]string, error) {
+	p := filepath.Join(cgroupRoot, ctr.path, name)
+
+	return readCgroup2MapPath(p)
+}

pkg/cgroups/cpu.go

@@ -121,3 +121,42 @@ func (c *cpuHandler) Stat(ctr *CgroupControl, m *Metrics) error {
 	m.CPU = CPUMetrics{Usage: usage}
 	return nil
 }
+
+// GetSystemCPUUsage returns the system usage for all the cgroups
+func GetSystemCPUUsage() (uint64, error) {
+	cgroupv2, err := IsCgroup2UnifiedMode()
+	if err != nil {
+		return 0, err
+	}
+	if !cgroupv2 {
+		p := filepath.Join(cgroupRoot, CPUAcct, "cpuacct.usage")
+		return readFileAsUint64(p)
+	}
+
+	files, err := ioutil.ReadDir(cgroupRoot)
+	if err != nil {
+		return 0, errors.Wrapf(err, "read directory %q", cgroupRoot)
+	}
+	var total uint64
+	for _, file := range files {
+		if !file.IsDir() {
+			continue
+		}
+		p := filepath.Join(cgroupRoot, file.Name(), "cpu.stat")
+
+		values, err := readCgroup2MapPath(p)
+		if err != nil {
+			return 0, err
+		}
+
+		if val, found := values["usage_usec"]; found {
+			v, err := strconv.ParseUint(cleanString(val[0]), 10, 0)
+			if err != nil {
+				return 0, err
+			}
+			total += v * 1000
+		}
+
+	}
+	return total, nil
+}