Calc proc cpu usage

main.go

package main

import (
       "fmt"
       "time"
       linuxproc "github.com/c9s/goprocinfo/linux"
)

func getCPUInfo() (*linuxproc.CPUInfo, error) {
       return linuxproc.ReadCPUInfo("/proc/cpuinfo")
}

func readProcessStat(pid uint64) (*linuxproc.ProcessStat, error) {
       return linuxproc.ReadProcessStat(fmt.Sprintf("/proc/%v/stat", pid))
}

func getCPUWorkTime() uint64 {
       ps, _ := linuxproc.ReadStat("/proc/stat")
       return ps.CPUStatAll.User + ps.CPUStatAll.Nice + ps.CPUStatAll.System + ps.CPUStatAll.IRQ + ps.CPUStatAll.SoftIRQ + ps.CPUStatAll.Steal + ps.CPUStatAll.Idle + ps.CPUStatAll.IOWait
}

func getProcWorkTime(pid uint64) uint64 {
       s, _ := readProcessStat(pid)
       return s.Stime + s.Utime + uint64(s.Cstime) + uint64(s.Cutime)
}

func main() {
       var pid uint64 = 12905
       captureInterval := time.Duration(5) * time.Second

       cpuinfo, _ := getCPUInfo()
       mul := float64(cpuinfo.NumCPU()) * 100

       prevProcCPUsage := getProcWorkTime(pid)
       prevCPUsage := getCPUWorkTime()

       for {
               currentCPUsage := getCPUWorkTime()
               currentProcCPUsage := getProcWorkTime(pid)

               fmt.Println(mul * float64(currentProcCPUsage-prevProcCPUsage) / float64(currentCPUsage-prevCPUsage+1))

               prevProcCPUsage = currentProcCPUsage
               prevCPUsage = currentCPUsage

               time.Sleep(captureInterval)
       }
}