open-nomad/helper/stats/cpu.go

84 lines
2.0 KiB
Go

// Copyright (c) HashiCorp, Inc.
// SPDX-License-Identifier: MPL-2.0
package stats
import (
"runtime"
"time"
)
var (
cpuTotalTicks uint64
)
// CpuStats calculates cpu usage percentage
type CpuStats struct {
prevCpuTime float64
prevTime time.Time
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) * float64(CpuTotalTicks()) / float64(c.totalCpus)
}
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
}
// Set the total ticks available across all cores.
func SetCpuTotalTicks(newCpuTotalTicks uint64) {
cpuTotalTicks = newCpuTotalTicks
}
// CpuTotalTicks calculates the total MHz available across all cores.
//
// Where asymetric cores are correctly detected, the total ticks is the sum of
// the performance across both core types.
//
// Where asymetric cores are not correctly detected (such as Intel 13th gen),
// the total ticks available is over-estimated, as we assume all cores are P
// cores.
func CpuTotalTicks() uint64 {
return cpuTotalTicks
}