runtime/pprof: Golang pprof cpu performance analysis, after the sampling frequency increases on the windows platform, the number of samples decreases #61665
Description
What version of Go are you using (go version)?
go version go1.20.6 windows/amd64
Does this issue reproduce with the latest release?
yes
What operating system and processor architecture are you using (go env)?
windows/amd64
windows11 (22H2, 22621.1992)
cpu x86 amd pyzen 5500
What did you do?
I want to increase the sampling frequency of cpu profiling and get more cpu sampling samples.
On the windows platform, I use the runtime.SetCPUProfileRate() interface to set the cpu performance analysis sampling frequency.
It was found that after increasing the sampling frequency, the number of cpu samples (Total samples) decreased abnormally.
When the computer is running the test program, the total CPU usage does not exceed 50%.
I tested again on the same computer using linux (centos stream 9, 5.14.0-340.el9.x86_64) through a virtual machine, and found that the sampling results were basically the same, and the results were normal.
Test code:
package main
import (
"fmt"
"os"
"runtime"
"runtime/pprof"
"time"
)
func inrun1() {
t1 := time.Now()
for {
if time.Since(t1) > time.Second*3 {
return
}
}
}
func main() {
samplesNum := 100
fn := fmt.Sprintf("cpuprof-%d--%s--main.prof", samplesNum, runtime.GOOS)
f, err := os.Create(fn)
if err != nil {
panic(err)
}
defer f.Close()
runtime.SetCPUProfileRate(samplesNum)
pprof.StartCPUProfile(f)
inrun1()
pprof.StopCPUProfile()
}
What did you expect to see?
I want to increase the sampling frequency of cpu profiling and get more cpu sampling samples.
What did you see instead?
It was found that after increasing the sampling frequency, the number of cpu samples (Total samples) decreased abnormally.
When the computer is running the test program, the total CPU usage does not exceed 50%.
I tested again on the same computer using linux (centos stream 9, 5.14.0-340.el9.x86_64) through a virtual machine, and found that the sampling results were basically the same, and the results were normal.
Specific sampling results:
windows11 (22H2, 22621.1992):
Sampling frequency Sampling result
25 Duration: 3.08s, Total samples = 2.92s (94.68%)
50 Duration: 3.19s, Total samples = 3s (93.94%)
100 Duration: 3.16s, Total samples = 1.91s (60.48%)
200 Duration: 3.18s, Total samples = 960ms (30.20%)
linux --centos-stream 9, 5.14.0-340.el9.x86_64:
Sampling frequency Sampling result
25 Duration: 3.13s, Total samples = 2.84s (90.68%)
50 Duration: 3.13s, Total samples = 2.84s (90.71%)
100 Duration: 3.13s, Total samples = 2.85s (91.06%)
200 Duration: 3.13s, Total samples = 2.85s (91.01%)