Updating QoS policy to be per-pod instead of per-resource.

Signed-off-by: Vishnu kannan <vishnuk@google.com>

pkg/kubelet/qos/policy.go

@@ -0,0 +1,85 @@
+/*
+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 qos
+
+import (
+	"k8s.io/kubernetes/pkg/api"
+)
+
+const (
+	PodInfraOOMAdj       int = -999
+	KubeletOOMScoreAdj   int = -999
+	KubeProxyOOMScoreAdj int = -999
+)
+
+// isBestEffort returns true if the container's resource requirements are best-effort.
+func isBestEffort(container *api.Container) bool {
+	// A container is best-effort if any of its resource requests is unspecified or 0.
+	if container.Resources.Requests.Memory().Value() == 0 ||
+		container.Resources.Requests.Cpu().Value() == 0 {
+		return true
+	}
+	return false
+}
+
+// isGuaranteed returns true if the container's resource requirements are Guaranteed.
+func isGuaranteed(container *api.Container) bool {
+	// A container is guaranteed if all its request == limit.
+	memoryRequest := container.Resources.Requests.Memory().Value()
+	memoryLimit := container.Resources.Limits.Memory().Value()
+	cpuRequest := container.Resources.Requests.Cpu().Value()
+	cpuLimit := container.Resources.Limits.Cpu().Value()
+	if memoryRequest != 0 &&
+		cpuRequest != 0 &&
+		cpuRequest == cpuLimit &&
+		memoryRequest == memoryLimit {
+		return true
+	}
+	return false
+}
+
+// GetContainerOOMAdjust returns the amount by which the OOM score of all processes in the
+// container should be adjusted. The OOM score of a process is the percentage of memory it consumes
+// multiplied by 10 (barring exceptional cases) + a configurable quantity which is between -1000
+// and 1000. Containers with higher OOM scores are killed if the system runs out of memory.
+// See https://lwn.net/Articles/391222/ for more information.
+func GetContainerOOMScoreAdjust(container *api.Container, memoryCapacity int64) int {
+	if isGuaranteed(container) {
+		// Guaranteed containers should be the last to get killed.
+		return -999
+	} else if isBestEffort(container) {
+		// Best-effort containers should be the first to be killed.
+		return 1000
+	} else {
+		// Burstable containers are a middle tier, between Guaranteed and Best-Effort. Ideally,
+		// we want to protect Burstable containers that consume less memory than requested.
+		// The formula below is a heuristic. A container requesting for 10% of a system's
+		// memory will have an OOM score adjust of 900. If a process in container Y
+		// uses over 10% of memory, its OOM score will be 1000. The idea is that containers
+		// which use more than their request will have an OOM score of 1000 and will be prime
+		// targets for OOM kills.
+		// Note that this is a heuristic, it won't work if a container has many small processes.
+		memoryRequest := container.Resources.Requests.Memory().Value()
+		oomScoreAdjust := 1000 - (1000*memoryRequest)/memoryCapacity
+		// A guaranteed container using 100% of memory can have an OOM score of 1. Ensure
+		// that burstable containers have a higher OOM score.
+		if oomScoreAdjust < 2 {
+			return 2
+		}
+		return int(oomScoreAdjust)
+	}
+}