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ae259748ef
The multiplication factor is 10 and not 100 as clear from some other comments in the same file. Also mentioned at https://lwn.net/Articles/391222/.
76 lines
3.3 KiB
Go
76 lines
3.3 KiB
Go
/*
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Copyright 2015 The Kubernetes Authors All rights reserved.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package qos
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import (
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"k8s.io/kubernetes/pkg/api"
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)
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const (
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PodInfraOOMAdj int = -999
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KubeletOOMScoreAdj int = -999
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KubeProxyOOMScoreAdj int = -999
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)
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// isMemoryBestEffort returns true if the container's memory requirements are best-effort.
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func isMemoryBestEffort(container *api.Container) bool {
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// A container is memory best-effort if its memory request is unspecified or 0.
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// If a request is specified, then the user expects some kind of resource guarantee.
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return container.Resources.Requests.Memory().Value() == 0
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}
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// isMemoryGuaranteed returns true if the container's memory requirements are Guaranteed.
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func isMemoryGuaranteed(container *api.Container) bool {
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// A container is memory guaranteed if its memory request == memory limit.
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// If memory request == memory limit, the user is very confident of resource consumption.
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memoryRequest := container.Resources.Requests.Memory()
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memoryLimit := container.Resources.Limits.Memory()
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return (*memoryRequest).Cmp(*memoryLimit) == 0 && memoryRequest.Value() != 0
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}
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// GetContainerOOMAdjust returns the amount by which the OOM score of all processes in the
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// container should be adjusted. The OOM score of a process is the percentage of memory it consumes
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// multiplied by 10 (barring exceptional cases) + a configurable quantity which is between -1000
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// and 1000. Containers with higher OOM scores are killed if the system runs out of memory.
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// See https://lwn.net/Articles/391222/ for more information.
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func GetContainerOOMScoreAdjust(container *api.Container, memoryCapacity int64) int {
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if isMemoryGuaranteed(container) {
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// Memory guaranteed containers should be the last to get killed.
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return -999
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} else if isMemoryBestEffort(container) {
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// Memory best-effort containers should be the first to be killed.
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return 1000
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} else {
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// Burstable containers are a middle tier, between Guaranteed and Best-Effort. Ideally,
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// we want to protect Burstable containers that consume less memory than requested.
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// The formula below is a heuristic. A container requesting for 10% of a system's
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// memory will have an oom score adjust of 900. If a process in container Y
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// uses over 10% of memory, its OOM score will be 1000. The idea is that containers
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// which use more than their request will have an OOM score of 1000 and will be prime
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// targets for OOM kills.
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// Note that this is a heuristic, it won't work if a container has many small processes.
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memoryRequest := container.Resources.Requests.Memory().Value()
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oomScoreAdjust := 1000 - (1000*memoryRequest)/memoryCapacity
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// A memory guaranteed container using 100% of memory can have an OOM score of 1. Ensure
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// that memory burstable containers have a higher OOM score.
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if oomScoreAdjust < 2 {
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return 2
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}
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return int(oomScoreAdjust)
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}
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}
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