Merge pull request #3471 from giuseppe/small-fixes-cgroups

cgroups v2: fix cpu time

libpod/stats.go

@@ -3,6 +3,7 @@
 package libpod
 
 import (
+	"runtime"
 	"strings"
 	"syscall"
 	"time"
@@ -105,7 +106,11 @@ func calculateCPUPercent(stats *cgroups.Metrics, previousCPU, previousSystem uin
 	if systemDelta > 0.0 && cpuDelta > 0.0 {
 		// gets a ratio of container cpu usage total, multiplies it by the number of cores (4 cores running
 		// at 100% utilization should be 400% utilization), and multiplies that by 100 to get a percentage
-		cpuPercent = (cpuDelta / systemDelta) * float64(len(stats.CPU.Usage.PerCPU)) * 100
+		nCPUS := len(stats.CPU.Usage.PerCPU)
+		if nCPUS == 0 {
+			nCPUS = runtime.NumCPU()
+		}
+		cpuPercent = (cpuDelta / systemDelta) * float64(nCPUS) * 100
 	}
 	return cpuPercent
 }

pkg/cgroups/cgroups.go

@@ -30,7 +30,7 @@ type CgroupControl struct {
 	additionalControllers []controller
 }
 
-// CPUUsage keeps stats for the CPU usage
+// CPUUsage keeps stats for the CPU usage (unit: nanoseconds)
 type CPUUsage struct {
 	Kernel uint64
 	Total  uint64

pkg/cgroups/cpu.go

@@ -85,12 +85,14 @@ func (c *cpuHandler) Stat(ctr *CgroupControl, m *Metrics) error {
 			if err != nil {
 				return err
 			}
+			usage.Kernel *= 1000
 		}
 		if val, found := values["system_usec"]; found {
 			usage.Total, err = strconv.ParseUint(cleanString(val[0]), 10, 0)
 			if err != nil {
 				return err
 			}
+			usage.Total *= 1000
 		}
 		// FIXME: How to read usage.PerCPU?
 	} else {