linux-kernel - Re: [ISSUE] sched/cgroup: Does cpu-cgroup still works fine nowadays?

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Date:	Tue, 13 May 2014 11:47:37 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Michael wang <wangyun@...ux.vnet.ibm.com>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Ingo Molnar <mingo@...nel.org>, Mike Galbraith <efault@....de>,
	Alex Shi <alex.shi@...aro.org>, Paul Turner <pjt@...gle.com>,
	Rik van Riel <riel@...hat.com>, Mel Gorman <mgorman@...e.de>,
	Daniel Lezcano <daniel.lezcano@...aro.org>
Subject: Re: [ISSUE] sched/cgroup: Does cpu-cgroup still works fine nowadays?

On Tue, May 13, 2014 at 11:34:43AM +0800, Michael wang wrote:
> During our testing, we found that the cpu.shares doesn't work as
> expected, the testing is:
> 

/me zaps all the kvm nonsense as that's non reproducable and only serves
to annoy.

Pro-tip: never use kvm to report cpu-cgroup issues.

> So is this results expected (I really do not think so...)?
> 
> Or that imply the cpu-cgroup got some issue to be fixed?

So what I did (WSM-EP 2x6x2):

mount none /cgroup -t cgroup -o cpu
mkdir -p /cgroup/a
mkdir -p /cgroup/b
mkdir -p /cgroup/c

echo $$ > /cgroup/a/tasks ; for ((i=0; i<12; i++)) ; do A.sh & done
echo $$ > /cgroup/b/tasks ; for ((i=0; i<12; i++)) ; do B.sh & done
echo $$ > /cgroup/c/tasks ; for ((i=0; i<12; i++)) ; do C.sh & done

echo 2048 > /cgroup/c/cpu.shares

Where [ABC].sh are spinners:

---
#!/bin/bash

while :; do :; done
---

for i in A B C ; do ps -deo pcpu,cmd | grep "${i}\.sh" | awk '{t += $1} END {print t}' ; done
639.7
629.8
1127.4

That is of course not perfect, but it's close enough.

Now you again.. :-)

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