Add back SystemCPUUsage

This function was accidently removed and is needed by podman.

Signed-off-by: Daniel J Walsh <dwalsh@redhat.com>

pkg/cgroups/cgroups_linux.go

@@ -702,3 +702,41 @@ func cpusetCopyFileFromParent(dir, file string, cgroupv2 bool) ([]byte, error) {
  }
  return data, nil
 }
+
+// SystemCPUUsage returns the system usage for all the cgroups
+func SystemCPUUsage() (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 := os.ReadDir(cgroupRoot)
+ if err != nil {
+ return 0, err
+ }
+ var total uint64
+ for _, file := range files {
+ if !file.IsDir() {
+ continue
+ }
+ p := filepath.Join(cgroupRoot, file.Name(), "cpu.stat")
+
+ values, err := readCgroupMapPath(p)
+ if err != nil {
+ return 0, err
+ }
+
+ if val, found := values["usage_usec"]; found {
+ v, err := strconv.ParseUint(cleanString(val[0]), 10, 64)
+ if err != nil {
+ return 0, err
+ }
+ total += v * 1000
+ }
+ }
+ return total, nil
+}