podman stats: improve cpu average calc

We can just calculate the cpu percent for the time the container is
running. There is no need to use datapoints.

Signed-off-by: Paul Holzinger <pholzing@redhat.com>

2 files changed, 2 insertions, 9 deletions

diff --git a/libpod/define/containerstate.go b/libpod/define/containerstate.go
index 23ba1f451..9ad3aec08 100644
--- a/libpod/define/containerstate.go
+++ b/libpod/define/containerstate.go
@@ -138,7 +138,6 @@ type ContainerStats struct {
 	CPU           float64
 	CPUNano       uint64
 	CPUSystemNano uint64
-	DataPoints    int64
 	SystemNano    uint64
 	MemUsage      uint64
 	MemLimit      uint64
diff --git a/libpod/stats.go b/libpod/stats.go
index dbb10a27e..7619ef345 100644
--- a/libpod/stats.go
+++ b/libpod/stats.go
@@ -66,8 +66,8 @@ func (c *Container) GetContainerStats(previousStats *define.ContainerStats) (*de
 	stats.Duration = cgroupStats.CPU.Usage.Total
 	stats.UpTime = time.Duration(stats.Duration)
 	stats.CPU = calculateCPUPercent(cgroupStats, previousCPU, now, previousStats.SystemNano)
-	stats.AvgCPU = calculateAvgCPU(stats.CPU, previousStats.AvgCPU, previousStats.DataPoints)
-	stats.DataPoints = previousStats.DataPoints + 1
+	// calc the average cpu usage for the time the container is running
+	stats.AvgCPU = calculateCPUPercent(cgroupStats, 0, now, uint64(c.state.StartedTime.UnixNano()))
 	stats.MemUsage = cgroupStats.Memory.Usage.Usage
 	stats.MemLimit = c.getMemLimit()
 	stats.MemPerc = (float64(stats.MemUsage) / float64(stats.MemLimit)) * 100
@@ -145,9 +145,3 @@ func calculateBlockIO(stats *cgroups.Metrics) (read uint64, write uint64) {
 	}
 	return
 }
-
-// calculateAvgCPU calculates the avg CPU percentage given the previous average and the number of data points.
-func calculateAvgCPU(statsCPU float64, prevAvg float64, prevData int64) float64 {
-	avgPer := ((prevAvg * float64(prevData)) + statsCPU) / (float64(prevData) + 1)
-	return avgPer
-}