144 lines
3.8 KiB
Go
144 lines
3.8 KiB
Go
/*
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* MinIO Cloud Storage, (C) 2019 MinIO, Inc.
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*
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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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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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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 cpu
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import (
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"sync"
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"time"
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)
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// rollingAvg holds the rolling average of the cpu load on the minio
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// server over its lifetime
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var rollingAvg *Load
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// cpuMeasureInterval is the interval of time between two
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// measurements of CPU load
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const cpuLoadMeasureInterval = 5 * time.Second
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// triggers the average load computation at server spawn
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func init() {
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rollingAvg = &Load{
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Min: float64(0),
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Max: float64(0),
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Avg: float64(0),
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}
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var rollingSum float64
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var cycles float64
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go func() {
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for {
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time.Sleep(cpuLoadMeasureInterval)
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cycles = cycles + 1
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currLoad := GetLoad()
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if rollingAvg.Max < currLoad.Max || rollingAvg.Max == 0 {
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rollingAvg.Max = currLoad.Max
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}
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if rollingAvg.Min > currLoad.Min || rollingAvg.Min == 0 {
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rollingAvg.Min = currLoad.Min
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}
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rollingSum = rollingSum + currLoad.Avg
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rollingAvg.Avg = rollingSum / cycles
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}
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}()
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}
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const (
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// cpuLoadWindow is the interval of time for which the
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// cpu utilization is measured
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cpuLoadWindow = 200 * time.Millisecond
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// cpuLoadSampleSize is the number of samples measured
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// for calculating cpu utilization
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cpuLoadSampleSize = 3
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// endOfTime represents the end of time
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endOfTime = time.Duration(1<<63 - 1)
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)
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// Load holds CPU utilization % measured in three intervals of 200ms each
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type Load struct {
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Avg float64 `json:"avg"`
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Max float64 `json:"max"`
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Min float64 `json:"min"`
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Error string `json:"error,omitempty"`
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}
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type counter struct{}
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// GetHistoricLoad returns the historic CPU utilization of the current process
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func GetHistoricLoad() Load {
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return *rollingAvg
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}
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// GetLoad returns the CPU utilization of the current process
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// This function works by calcualating the amount of cpu clock
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// cycles the current process used in a given time window
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//
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// This corresponds to the CPU utilization calculation done by
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// tools like top. Here, we use the getclocktime with the
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// CLOCK_PROCESS_CPUTIME_ID parameter to obtain the total number of
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// clock ticks used by the process so far. Then we sleep for
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// 200ms and obtain the the total number of clock ticks again. The
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// difference between the two counts provides us the number of
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// clock ticks used by the process in the 200ms interval.
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//
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// The ratio of clock ticks used (measured in nanoseconds) to number
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// of nanoseconds in 200 milliseconds provides us the CPU usage
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// for the process currently
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func GetLoad() Load {
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vals := make(chan time.Duration, 3)
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var wg sync.WaitGroup
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for i := 0; i < cpuLoadSampleSize; i++ {
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cpuCounter, err := newCounter()
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if err != nil {
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return Load{
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Error: err.Error(),
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}
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}
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wg.Add(1)
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go func() {
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start := cpuCounter.now()
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time.Sleep(cpuLoadWindow)
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end := cpuCounter.now()
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vals <- end.Sub(start)
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wg.Done()
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}()
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}
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wg.Wait()
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sum := time.Duration(0)
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max := time.Duration(0)
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min := (endOfTime)
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for i := 0; i < cpuLoadSampleSize; i++ {
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val := <-vals
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sum = sum + val
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if val > max {
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max = val
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}
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if val < min {
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min = val
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}
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}
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close(vals)
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avg := sum / 3
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return Load{
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Avg: toFixed4(float64(avg)/float64(200*time.Millisecond)) * 100,
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Max: toFixed4(float64(max)/float64(200*time.Millisecond)) * 100,
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Min: toFixed4(float64(min)/float64(200*time.Millisecond)) * 100,
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Error: "",
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}
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}
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