From a84ab35dc809f9ebedb290db234abdf43afe5a21 Mon Sep 17 00:00:00 2001 From: Giuseppe Scrivano Date: Fri, 1 Nov 2019 20:52:08 +0100 Subject: stats: fix calculation for the CPU time Closes: https://github.com/containers/libpod/issues/4409 Signed-off-by: Giuseppe Scrivano --- libpod/stats.go | 24 +++++++++++------------- 1 file changed, 11 insertions(+), 13 deletions(-) (limited to 'libpod') diff --git a/libpod/stats.go b/libpod/stats.go index 5513abce5..3b5e0958c 100644 --- a/libpod/stats.go +++ b/libpod/stats.go @@ -3,7 +3,6 @@ package libpod import ( - "runtime" "strings" "syscall" "time" @@ -56,8 +55,8 @@ func (c *Container) GetContainerStats(previousStats *ContainerStats) (*Container } previousCPU := previousStats.CPUNano - previousSystem := previousStats.SystemNano - stats.CPU = calculateCPUPercent(cgroupStats, previousCPU, previousSystem) + now := uint64(time.Now().UnixNano()) + stats.CPU = calculateCPUPercent(cgroupStats, previousCPU, now, previousStats.SystemNano) stats.MemUsage = cgroupStats.Memory.Usage.Usage stats.MemLimit = getMemLimit(cgroupStats.Memory.Usage.Limit) stats.MemPerc = (float64(stats.MemUsage) / float64(stats.MemLimit)) * 100 @@ -67,7 +66,7 @@ func (c *Container) GetContainerStats(previousStats *ContainerStats) (*Container } stats.BlockInput, stats.BlockOutput = calculateBlockIO(cgroupStats) stats.CPUNano = cgroupStats.CPU.Usage.Total - stats.SystemNano = cgroupStats.CPU.Usage.Kernel + stats.SystemNano = now // Handle case where the container is not in a network namespace if netStats != nil { stats.NetInput = netStats.TxBytes @@ -98,20 +97,19 @@ func getMemLimit(cgroupLimit uint64) uint64 { return cgroupLimit } -func calculateCPUPercent(stats *cgroups.Metrics, previousCPU, previousSystem uint64) float64 { +// calculateCPUPercent calculates the cpu usage using the latest measurement in stats. +// previousCPU is the last value of stats.CPU.Usage.Total measured at the time previousSystem. +// (now - previousSystem) is the time delta in nanoseconds, between the measurement in previousCPU +// and the updated value in stats. +func calculateCPUPercent(stats *cgroups.Metrics, previousCPU, now, previousSystem uint64) float64 { var ( cpuPercent = 0.0 cpuDelta = float64(stats.CPU.Usage.Total - previousCPU) - systemDelta = float64(uint64(time.Now().UnixNano()) - previousSystem) + systemDelta = float64(now - previousSystem) ) 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 - nCPUS := len(stats.CPU.Usage.PerCPU) - if nCPUS == 0 { - nCPUS = runtime.NumCPU() - } - cpuPercent = (cpuDelta / systemDelta) * float64(nCPUS) * 100 + // gets a ratio of container cpu usage total, and multiplies that by 100 to get a percentage + cpuPercent = (cpuDelta / systemDelta) * 100 } return cpuPercent } -- cgit v1.2.3-54-g00ecf