open-nomad/client/stats/cpu.go
2016-06-11 17:31:49 +02:00

63 lines
1.4 KiB
Go

package stats
import (
"runtime"
"time"
shelpers "github.com/hashicorp/nomad/helper/stats"
)
// CpuStats calculates cpu usage percentage
type CpuStats struct {
prevCpuTime float64
prevTime time.Time
clkSpeed float64
totalCpus int
}
// NewCpuStats returns a cpu stats calculator
func NewCpuStats() *CpuStats {
numCpus := runtime.NumCPU()
cpuStats := &CpuStats{
totalCpus: numCpus,
}
return cpuStats
}
// Percent calculates the cpu usage percentage based on the current cpu usage
// and the previous cpu usage where usage is given as time in nanoseconds spend
// in the cpu
func (c *CpuStats) Percent(cpuTime float64) float64 {
now := time.Now()
if c.prevCpuTime == 0.0 {
// invoked first time
c.prevCpuTime = cpuTime
c.prevTime = now
return 0.0
}
timeDelta := now.Sub(c.prevTime).Nanoseconds()
ret := c.calculatePercent(c.prevCpuTime, cpuTime, timeDelta)
c.prevCpuTime = cpuTime
c.prevTime = now
return ret
}
// TicksConsumed calculates the total ticks consumes by the process across all
// cpu cores
func (c *CpuStats) TicksConsumed(percent float64) float64 {
return (percent / 100) * shelpers.TotalTicksAvailable()
}
func (c *CpuStats) calculatePercent(t1, t2 float64, timeDelta int64) float64 {
vDelta := t2 - t1
if timeDelta <= 0 || vDelta <= 0.0 {
return 0.0
}
overall_percent := (vDelta / float64(timeDelta)) * 100.0
return overall_percent
}