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Subject: Re: [PATCH 6/9] Include idle and iowait fields in cpuacct
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: Glauber Costa <glommer@parallels.com>
Cc: linux-kernel@vger.kernel.org, xemul@parallels.com, paul@paulmenage.org,
        lizf@cn.fujitsu.com, daniel.lezcano@free.fr, mingo@elte.hu,
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Date: Tue, 20 Sep 2011 11:21:30 +0200
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On Wed, 2011-09-14 at 17:04 -0300, Glauber Costa wrote:
> These are slightly different from the others though:
> (note to reviewers: might be better to put those in a separate
> array?)
> 
> Since idle/iowait are a property of the system - by definition,
> no process from any cgroup is running when the system is idle,
> they are system wide. So what these fields really mean, are baselines
> for when the cgroup was created. It allows the cgroup to start
> counting idle/iowait from 0.

Alternatively you can make iowait based on nr_uninterruptible per cgroup
and count all ticks _this_ cgroup was idle.

Now all that would need moar accounting...