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When I read source code about " docker stat", the current is :
cpuPercent = (cpuDelta / systemDelta) * float64(len(v.CpuStats.CpuUsage.PercpuUsage))
https://github.com/docker/docker/blob/0d445685b8d628a938790e50517f3fb949b300e0/api/client/stats.go#L199
I do not understand why " * float64(len(v.CpuStats.CpuUsage.PercpuUsage)) ", (cpuDelta / systemDelta) is Correct。
cpuDelta = float64(v.CpuStats.CpuUsage.TotalUsage - previousCPU)
systemDelta = float64(v.CpuStats.SystemUsage - previousSystem)
so total cpu delta / total system delta is correct , not need to multiplied by CPU kernal count.
Am I think right?
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GordonTheTurtle commentedon Jun 1, 2015
Hi!
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[-]Why "docker stat " calculation must multiplied by CPU kernal count？[/-][+][BUG REPORT INFORMATION]Why "docker stat " calculation must multiplied by CPU kernal count？[/+]update stats.go
[-][BUG REPORT INFORMATION]Why "docker stat " calculation must multiplied by CPU kernal count？[/-][+]Why "docker stat " calculation must multiplied by CPU kernal count？[/+]coolljt0725 commentedon Jun 1, 2015
I have some comments in #13627 (comment) about this
thaJeztah commentedon Jun 1, 2015
From the comment linked by @coolljt0725;
Agreed; for example, on a 4-core system, cpu usage can be anywhere between 0 and 400%, so it has to be multiplied by the number of cores.
I'm going to close this issue, because I don't think this change is correct, but feel free to comment if you think I closed this by mistake.
Liuyanglong commentedon Jun 9, 2015
@thaJeztah @coolljt0725
We have different opinions on this question.
I think the "stats CPU%" should be the average, but sourcecode says it should be total.
I have a Pic about docker stats run on my server, one of the containers is larger than 100%, so if do not know how many cpu cores on my server, I will never know how much cpu idle left.
coolljt0725 commentedon Jun 9, 2015
@Liuyanglong We can get the cpu cores by using
docker info, so I don't think this is a problem.Liuyanglong commentedon Jun 9, 2015
@coolljt0725 I do not think this is a problom， but it feel strange .
I want get a number show me the esource usage from '' docker stats", but now I must get the number from 'docker stats' and 'docker info'.For me, I care more about average.