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cpuacct.go
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cpuacct.go
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package fs
import (
"bufio"
"fmt"
"os"
"path/filepath"
"runtime"
"strconv"
"strings"
"time"
"github.com/dotcloud/docker/pkg/cgroups"
"github.com/dotcloud/docker/pkg/system"
)
var (
cpuCount = float64(runtime.NumCPU())
clockTicks = float64(system.GetClockTicks())
)
type cpuacctGroup struct {
}
func (s *cpuacctGroup) Set(d *data) error {
// we just want to join this group even though we don't set anything
if _, err := d.join("cpuacct"); err != nil && err != cgroups.ErrNotFound {
return err
}
return nil
}
func (s *cpuacctGroup) Remove(d *data) error {
return removePath(d.path("cpuacct"))
}
func (s *cpuacctGroup) Stats(d *data) (map[string]float64, error) {
var (
startCpu, lastCpu, startSystem, lastSystem, startUsage, lastUsage float64
percentage float64
paramData = make(map[string]float64)
)
path, err := d.path("cpuacct")
if startCpu, err = s.getCpuUsage(d, path); err != nil {
return nil, err
}
if startSystem, err = s.getSystemCpuUsage(d); err != nil {
return nil, err
}
startUsageTime := time.Now()
if startUsage, err = getCgroupParamFloat64(path, "cpuacct.usage"); err != nil {
return nil, err
}
// sample for 100ms
time.Sleep(100 * time.Millisecond)
if lastCpu, err = s.getCpuUsage(d, path); err != nil {
return nil, err
}
if lastSystem, err = s.getSystemCpuUsage(d); err != nil {
return nil, err
}
usageSampleDuration := time.Since(startUsageTime)
if lastUsage, err = getCgroupParamFloat64(path, "cpuacct.usage"); err != nil {
return nil, err
}
var (
deltaProc = lastCpu - startCpu
deltaSystem = lastSystem - startSystem
deltaUsage = lastUsage - startUsage
)
if deltaSystem > 0.0 {
percentage = ((deltaProc / deltaSystem) * clockTicks) * cpuCount
}
// NOTE: a percentage over 100% is valid for POSIX because that means the
// processes is using multiple cores
paramData["percentage"] = percentage
// Delta usage is in nanoseconds of CPU time so get the usage (in cores) over the sample time.
paramData["usage"] = deltaUsage / float64(usageSampleDuration.Nanoseconds())
return paramData, nil
}
func (s *cpuacctGroup) getProcStarttime(d *data) (float64, error) {
rawStart, err := system.GetProcessStartTime(d.pid)
if err != nil {
return 0, err
}
return strconv.ParseFloat(rawStart, 64)
}
func (s *cpuacctGroup) getSystemCpuUsage(d *data) (float64, error) {
f, err := os.Open("/proc/stat")
if err != nil {
return 0, err
}
defer f.Close()
sc := bufio.NewScanner(f)
for sc.Scan() {
parts := strings.Fields(sc.Text())
switch parts[0] {
case "cpu":
if len(parts) < 8 {
return 0, fmt.Errorf("invalid number of cpu fields")
}
var total float64
for _, i := range parts[1:8] {
v, err := strconv.ParseFloat(i, 64)
if err != nil {
return 0.0, fmt.Errorf("Unable to convert value %s to float: %s", i, err)
}
total += v
}
return total, nil
default:
continue
}
}
return 0, fmt.Errorf("invalid stat format")
}
func (s *cpuacctGroup) getCpuUsage(d *data, path string) (float64, error) {
cpuTotal := 0.0
f, err := os.Open(filepath.Join(path, "cpuacct.stat"))
if err != nil {
return 0.0, err
}
defer f.Close()
sc := bufio.NewScanner(f)
for sc.Scan() {
_, v, err := getCgroupParamKeyValue(sc.Text())
if err != nil {
return 0.0, err
}
// set the raw data in map
cpuTotal += v
}
return cpuTotal, nil
}