1
0
Fork 0
mirror of https://github.com/moby/moby.git synced 2022-11-09 12:21:53 -05:00
moby--moby/daemon/stats/collector_unix.go
Ian Campbell 115f91d757 Correct CPU usage calculation in presence of offline CPUs and newer Linux
In https://github.com/torvalds/linux/commit/5ca3726 (released in v4.7-rc1) the
content of the `cpuacct.usage_percpu` file in sysfs was changed to include both
online and offline cpus. This broke the arithmetic in the stats helpers used by
`docker stats`, since it was using the length of the PerCPUUsage array as a
proxy for the number of online CPUs.

Add current number of online CPUs to types.StatsJSON and use it in the
calculation.

Keep a fallback to `len(v.CPUStats.CPUUsage.PercpuUsage)` so this code
continues to work when talking to an older daemon. An old client talking to a
new daemon will ignore the new field and behave as before.

Fixes #28941.

Signed-off-by: Ian Campbell <ian.campbell@docker.com>
2017-03-10 10:24:33 +00:00

79 lines
1.8 KiB
Go

// +build !windows,!solaris
package stats
import (
"fmt"
"os"
"strconv"
"strings"
"github.com/opencontainers/runc/libcontainer/system"
)
/*
#include <unistd.h>
*/
import "C"
// platformNewStatsCollector performs platform specific initialisation of the
// Collector structure.
func platformNewStatsCollector(s *Collector) {
s.clockTicksPerSecond = uint64(system.GetClockTicks())
}
const nanoSecondsPerSecond = 1e9
// 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 (s *Collector) getSystemCPUUsage() (uint64, error) {
var line string
f, err := os.Open("/proc/stat")
if err != nil {
return 0, err
}
defer func() {
s.bufReader.Reset(nil)
f.Close()
}()
s.bufReader.Reset(f)
err = nil
for err == nil {
line, err = s.bufReader.ReadString('\n')
if err != nil {
break
}
parts := strings.Fields(line)
switch parts[0] {
case "cpu":
if len(parts) < 8 {
return 0, fmt.Errorf("invalid number of cpu fields")
}
var totalClockTicks uint64
for _, i := range parts[1:8] {
v, err := strconv.ParseUint(i, 10, 64)
if err != nil {
return 0, fmt.Errorf("Unable to convert value %s to int: %s", i, err)
}
totalClockTicks += v
}
return (totalClockTicks * nanoSecondsPerSecond) /
s.clockTicksPerSecond, nil
}
}
return 0, fmt.Errorf("invalid stat format. Error trying to parse the '/proc/stat' file")
}
func (s *Collector) getNumberOnlineCPUs() (uint32, error) {
i, err := C.sysconf(C._SC_NPROCESSORS_ONLN)
if err != nil {
return 0, err
}
return uint32(i), nil
}