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Subject: Re: [PATCH 1/9] Remove parent field in cpuacct cgroup
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: Balbir Singh <bsingharora@gmail.com>
Cc: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>,
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Date: Fri, 23 Sep 2011 16:35:26 +0200
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On Fri, 2011-09-23 at 13:39 +0530, Balbir Singh wrote:
> >> Android makes heavy use of cpuacct as well. We invented it to do cpu
> >> accounting independent of control
> >
> > But its a massive waste of time to have to iterate a double hierarchy,
> > cache-miss heaven.
> >
> 
> By double hierarchy you mean both cpu and cpuacct? 

Yes

> What if they are not mounted together?

I was asking if there was a real reason not to have that.

> > Or so people really have independent cgroups as well? I thought people
> > just co-mount all this crap.
> >
> 
> Please see
> http://code.google.com/p/cgroupmgr/wiki/cgroupsForAndroid
> http://stackoverflow.com/questions/6814207/android-cpuacct-usage-file
> 
> AFAIK, some versions mount cpuacct at /acct and independent of cpu cgroups

They do now, but can that be fixed? Is there a sane use-case?

Overhead really must come down of all this crap.