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68 lines
2.0 KiB
Go
68 lines
2.0 KiB
Go
// +build linux
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/*
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Copyright 2018 The Kubernetes Authors.
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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 kuberuntime
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const (
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// Taken from lmctfy https://github.com/google/lmctfy/blob/master/lmctfy/controllers/cpu_controller.cc
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minShares = 2
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sharesPerCPU = 1024
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milliCPUToCPU = 1000
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// 100000 is equivalent to 100ms
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quotaPeriod = 100000
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minQuotaPeriod = 1000
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)
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// milliCPUToShares converts milliCPU to CPU shares
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func milliCPUToShares(milliCPU int64) int64 {
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if milliCPU == 0 {
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// Return 2 here to really match kernel default for zero milliCPU.
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return minShares
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}
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// Conceptually (milliCPU / milliCPUToCPU) * sharesPerCPU, but factored to improve rounding.
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shares := (milliCPU * sharesPerCPU) / milliCPUToCPU
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if shares < minShares {
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return minShares
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}
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return shares
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}
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// milliCPUToQuota converts milliCPU to CFS quota and period values
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func milliCPUToQuota(milliCPU int64, period int64) (quota int64) {
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// CFS quota is measured in two values:
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// - cfs_period_us=100ms (the amount of time to measure usage across)
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// - cfs_quota=20ms (the amount of cpu time allowed to be used across a period)
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// so in the above example, you are limited to 20% of a single CPU
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// for multi-cpu environments, you just scale equivalent amounts
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// see https://www.kernel.org/doc/Documentation/scheduler/sched-bwc.txt for details
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if milliCPU == 0 {
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return
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}
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// we then convert your milliCPU to a value normalized over a period
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quota = (milliCPU * period) / milliCPUToCPU
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// quota needs to be a minimum of 1ms.
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if quota < minQuotaPeriod {
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quota = minQuotaPeriod
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}
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return
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}
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