Re: question on sched-rt group allocation cap: sched_rt_runtime_us

[Anirban Sinha]

On 2009-09-07, at 9:44 AM, Anirban Sinha wrote:

> -----Original Message-----
> From: Mike Galbraith [mailto:efault@xxxxxx]
> Sent: Sun 9/6/2009 11:54 PM
> To: Anirban Sinha
> Cc: Lucas De Marchi; linux-kernel@xxxxxxxxxxxxxxx; Peter Zijlstra;  
> Ingo Molnar
> Subject: RE: question on sched-rt group allocation cap:  
> sched_rt_runtime_us
>
> On Sun, 2009-09-06 at 17:18 -0700, Anirban Sinha wrote:
> >
> >
> > > Dunno.  Fly or die little patchlet (toss).
> >
> > > sched: allow the user to disable RT bandwidth aggregation.
> >
> > Hmm. Interesting. With this change, my results are as follows:
> >
> > rt_runtime/rt_period   % of reg iterations
> >
> > 0.2                    100%
> > 0.25                   100%
> > 0.3                    100%
> > 0.4                    100%
> > 0.5                    82%
> > 0.6                    66%
> > 0.7                    54%
> > 0.8                    46%
> > 0.9                    38.5%
> > 0.95                   32%
> >
> >
> > This results are on a quad core blade. Does it still makes sense
> > though?
> > Can anyone else run the same tests on a quadcore over the latest
> > kernel? I will patch our 2.6.26 kernel with upstream fixes and rerun
> > these tests on tuesday.
>
> I tested tip (v2.6.31-rc9-1357-ge6a3cd0) with a little perturbation
> measurement proglet on an isolated Q6600 core.


Thanks Mike. Is this on a single core machine (or one core carved out  
of N)?  We may have some newer patches missing from the 2.6.26 kernel  
that fixes some accounting bugs. I will do a review and rerun the test  
after applying the upstream patches.

Ani

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