Subject: Re: question on sched-rt group allocation cap: sched_rt_runtime_us
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: Mike Galbraith <efault@gmx.de>
Cc: Ani <asinha@zeugmasystems.com>,
       Lucas De Marchi <lucas.de.marchi@gmail.com>,
       linux-kernel@vger.kernel.org, Ingo Molnar <mingo@elte.hu>
In-Reply-To: <1252218779.6126.17.camel@marge.simson.net>
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	 <dhcf5-263-13@gated-at.bofh.it>
	 <36bbf267-be27-4c9e-b782-91ed32a1dfe9@g1g2000pra.googlegroups.com>
	 <1252218779.6126.17.camel@marge.simson.net>
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Date: Mon, 07 Sep 2009 09:59:34 +0200
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On Sun, 2009-09-06 at 08:32 +0200, Mike Galbraith wrote:
> On Sat, 2009-09-05 at 19:32 -0700, Ani wrote: 
> > On Sep 5, 3:50 pm, Lucas De Marchi <lucas.de.mar...@gmail.com> wrote:
> > >
> > > Indeed. I've tested this same test program in a single core machine and it
> > > produces the expected behavior:
> > >
> > > rt_runtime_us / rt_period_us     % loops executed in SCHED_OTHER
> > > 95%                              4.48%
> > > 60%                              54.84%
> > > 50%                              86.03%
> > > 40%                              OTHER completed first
> > >
> > 
> > Hmm. This does seem to indicate that there is some kind of
> > relationship with SMP. So I wonder whether there is a way to turn this
> > 'RT bandwidth accumulation' heuristic off.
> 
> No there isn't..

Actually there is, use cpusets to carve the system into partitions.

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