containerd/sys/proc.go
Michael Crosby 51510a8806 Move osutil to sys package
Signed-off-by: Michael Crosby <crosbymichael@gmail.com>
2016-11-29 15:38:24 -08:00

64 lines
1.4 KiB
Go

// +build linux
package sys
import (
"bufio"
"fmt"
"os"
"strconv"
"strings"
"github.com/opencontainers/runc/libcontainer/system"
)
const nanoSecondsPerSecond = 1e9
var clockTicksPerSecond = uint64(system.GetClockTicks())
// GetSystemCPUUsage returns the host system's cpu usage in
// nanoseconds. An error is returned if the format of the underlying
// file does not match.
//
// Uses /proc/stat defined by POSIX. Looks for the cpu
// statistics line and then sums up the first seven fields
// provided. See `man 5 proc` for details on specific field
// information.
func GetSystemCPUUsage() (uint64, error) {
var line string
f, err := os.Open("/proc/stat")
if err != nil {
return 0, err
}
bufReader := bufio.NewReaderSize(nil, 128)
defer func() {
bufReader.Reset(nil)
f.Close()
}()
bufReader.Reset(f)
err = nil
for err == nil {
line, err = bufReader.ReadString('\n')
if err != nil {
break
}
parts := strings.Fields(line)
switch parts[0] {
case "cpu":
if len(parts) < 8 {
return 0, fmt.Errorf("bad format of cpu stats")
}
var totalClockTicks uint64
for _, i := range parts[1:8] {
v, err := strconv.ParseUint(i, 10, 64)
if err != nil {
return 0, fmt.Errorf("error parsing cpu stats")
}
totalClockTicks += v
}
return (totalClockTicks * nanoSecondsPerSecond) /
clockTicksPerSecond, nil
}
}
return 0, fmt.Errorf("bad stats format")
}