Add QoS support on node

pkg/util/oom/oom_linux.go

@@ -0,0 +1,112 @@
+// +build cgo,linux
+
+/*
+Copyright 2015 The Kubernetes Authors All rights reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package oom
+
+import (
+	"fmt"
+	"io/ioutil"
+	"path"
+	"strconv"
+
+	"github.com/docker/libcontainer/cgroups/fs"
+	"github.com/docker/libcontainer/configs"
+	"github.com/golang/glog"
+)
+
+func NewOomAdjuster() *OomAdjuster {
+	oomAdjuster := &OomAdjuster{
+		pidLister:        getPids,
+		ApplyOomScoreAdj: applyOomScoreAdj,
+	}
+	oomAdjuster.ApplyOomScoreAdjContainer = oomAdjuster.applyOomScoreAdjContainer
+	return oomAdjuster
+}
+
+func getPids(cgroupName string) ([]int, error) {
+	fsManager := fs.Manager{
+		Cgroups: &configs.Cgroup{
+			Name: cgroupName,
+		},
+	}
+	return fsManager.GetPids()
+}
+
+// Writes 'value' to /proc/<pid>/oom_score_adj. PID = 0 means self
+func applyOomScoreAdj(pid int, oomScoreAdj int) error {
+	if pid < 0 {
+		return fmt.Errorf("invalid PID %d specified for oom_score_adj", pid)
+	}
+
+	var pidStr string
+	if pid == 0 {
+		pidStr = "self"
+	} else {
+		pidStr = strconv.Itoa(pid)
+	}
+
+	oomScoreAdjPath := path.Join("/proc", pidStr, "oom_score_adj")
+	maxTries := 2
+	var err error
+	for i := 0; i < maxTries; i++ {
+		_, readErr := ioutil.ReadFile(oomScoreAdjPath)
+		if readErr != nil {
+			err = fmt.Errorf("failed to read oom_score_adj: %v", readErr)
+		} else if writeErr := ioutil.WriteFile(oomScoreAdjPath, []byte(strconv.Itoa(oomScoreAdj)), 0700); writeErr != nil {
+			err = fmt.Errorf("failed to set oom_score_adj to %d: %v", oomScoreAdj, writeErr)
+		} else {
+			return nil
+		}
+	}
+
+	return err
+}
+
+// Writes 'value' to /proc/<pid>/oom_score_adj for all processes in cgroup cgroupName.
+// Keeps trying to write until the process list of the cgroup stabilizes, or until maxTries tries.
+func (oomAdjuster *OomAdjuster) applyOomScoreAdjContainer(cgroupName string, oomScoreAdj, maxTries int) error {
+	adjustedProcessSet := make(map[int]bool)
+	for i := 0; i < maxTries; i++ {
+		continueAdjusting := false
+		pidList, err := oomAdjuster.pidLister(cgroupName)
+		if err != nil {
+			continueAdjusting = true
+			glog.Errorf("Error getting process list for cgroup %s: %+v", cgroupName, err)
+		} else if len(pidList) == 0 {
+			continueAdjusting = true
+		} else {
+			for _, pid := range pidList {
+				if !adjustedProcessSet[pid] {
+					continueAdjusting = true
+					if err = oomAdjuster.ApplyOomScoreAdj(pid, oomScoreAdj); err == nil {
+						adjustedProcessSet[pid] = true
+					}
+				}
+			}
+		}
+		if !continueAdjusting {
+			return nil
+		}
+		// There's a slight race. A process might have forked just before we write its OOM score adjust.
+		// The fork might copy the parent process's old OOM score, then this function might execute and
+		// update the parent's OOM score, but the forked process id might not be reflected in cgroup.procs
+		// for a short amount of time. So this function might return without changing the forked process's
+		// OOM score. Very unlikely race, so ignoring this for now.
+	}
+	return fmt.Errorf("exceeded maxTries, some processes might not have desired OOM score")
+}