d0f9e6dc36
cpu.cfs_period_us is measured in microseconds in the kernel but provided in time.Duration by the user, that change clarifies the code to make this evident to the reader. Also, the minimum value for that feature is 1ms and not 1μs, and this change alters the validation to reject values smaller than 1ms.
56 lines
1.8 KiB
Go
56 lines
1.8 KiB
Go
//go:build linux
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// +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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milliCPUToCPU = 1000
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// 100000 microseconds is equivalent to 100ms
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quotaPeriod = 100000
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// 1000 microseconds is equivalent to 1ms
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// defined here:
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// https://github.com/torvalds/linux/blob/cac03ac368fabff0122853de2422d4e17a32de08/kernel/sched/core.c#L10546
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minQuotaPeriod = 1000
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)
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// milliCPUToQuota converts milliCPU to CFS quota and period values
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// Input parameters and resulting value is number of microseconds.
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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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