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Copy pathcpu.go
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143 lines (130 loc) · 3.79 KB
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/*
* Minio Cloud Storage, (C) 2019 Minio, Inc.
*
* 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 cpu
import (
"sync"
"time"
)
// rollingAvg holds the rolling average of the cpu load on the minio
// server over its lifetime
var rollingAvg *Load
// cpuMeasureInterval is the interval of time between two
// measurements of CPU load
const cpuLoadMeasureInterval = 5 * time.Second
// triggers the average load computation at server spawn
func init() {
rollingAvg = &Load{
Min: float64(0),
Max: float64(0),
Avg: float64(0),
}
var rollingSum float64
var cycles float64
go func() {
for {
time.Sleep(cpuLoadMeasureInterval)
cycles = cycles + 1
currLoad := GetLoad()
if rollingAvg.Max < currLoad.Max || rollingAvg.Max == 0 {
rollingAvg.Max = currLoad.Max
}
if rollingAvg.Min > currLoad.Min || rollingAvg.Min == 0 {
rollingAvg.Min = currLoad.Min
}
rollingSum = rollingSum + currLoad.Avg
rollingAvg.Avg = rollingSum / cycles
}
}()
}
const (
// cpuLoadWindow is the interval of time for which the
// cpu utilization is measured
cpuLoadWindow = 200 * time.Millisecond
// cpuLoadSampleSize is the number of samples measured
// for calculating cpu utilization
cpuLoadSampleSize = 3
// endOfTime represents the end of time
endOfTime = time.Duration(1<<63 - 1)
)
// Load holds CPU utilization % measured in three intervals of 200ms each
type Load struct {
Avg float64 `json:"avg"`
Max float64 `json:"max"`
Min float64 `json:"min"`
Error string `json:"error,omitempty"`
}
type counter struct{}
// GetHistoricLoad returns the historic CPU utilization of the current process
func GetHistoricLoad() Load {
return *rollingAvg
}
// GetLoad returns the CPU utilization of the current process
// This function works by calcualating the amount of cpu clock
// cycles the current process used in a given time window
//
// This corresponds to the CPU utilization calculation done by
// tools like top. Here, we use the getclocktime with the
// CLOCK_PROCESS_CPUTIME_ID parameter to obtain the total number of
// clock ticks used by the process so far. Then we sleep for
// 200ms and obtain the the total number of clock ticks again. The
// difference between the two counts provides us the number of
// clock ticks used by the process in the 200ms interval.
//
// The ratio of clock ticks used (measured in nanoseconds) to number
// of nanoseconds in 200 milliseconds provides us the CPU usage
// for the process currently
func GetLoad() Load {
vals := make(chan time.Duration, 3)
wg := sync.WaitGroup{}
for i := 0; i < cpuLoadSampleSize; i++ {
cpuCounter, err := newCounter()
if err != nil {
return Load{
Error: err.Error(),
}
}
wg.Add(1)
go func() {
start := cpuCounter.now()
time.Sleep(cpuLoadWindow)
end := cpuCounter.now()
vals <- end.Sub(start)
wg.Done()
}()
}
wg.Wait()
sum := time.Duration(0)
max := time.Duration(0)
min := (endOfTime)
for i := 0; i < cpuLoadSampleSize; i++ {
val := <-vals
sum = sum + val
if val > max {
max = val
}
if val < min {
min = val
}
}
close(vals)
avg := sum / 3
return Load{
Avg: toFixed4(float64(avg)/float64(200*time.Millisecond)) * 100,
Max: toFixed4(float64(max)/float64(200*time.Millisecond)) * 100,
Min: toFixed4(float64(min)/float64(200*time.Millisecond)) * 100,
Error: "",
}
}