Messages in this thread | | | Subject | Re: question on sched-rt group allocation cap: sched_rt_runtime_us | From | Anirban Sinha <> | Date | Tue, 8 Sep 2009 00:08:31 -0700 |
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On 2009-09-07, at 9:42 AM, Anirban Sinha wrote:
> > > > -----Original Message----- > From: Peter Zijlstra [mailto:a.p.zijlstra@chello.nl] > Sent: Mon 9/7/2009 12:59 AM > To: Mike Galbraith > Cc: Anirban Sinha; Lucas De Marchi; linux-kernel@vger.kernel.org; > Ingo Molnar > Subject: Re: question on sched-rt group allocation cap: > sched_rt_runtime_us > > 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.
hmm. ok. I looked at the code a little bit. It seems to me that the 'borrowing' of RT runtimes occurs only from rt runqueues belonging to the same root domain. And partition_sched_domains() is the only external interface that can be used to create root domain out of a CPU set. But then I think it needs to have CGROUPS/USER groups enabled? Right?
--Ani
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