Re: [PATCH] sched/rt: fix SCHED_RR across cgroups

From: Dario Faggioli
Date: Wed May 23 2012 - 09:32:42 EST


On Sat, 2012-05-19 at 13:37 -0700, Colin Cross wrote:
> > I would say it is. That's what you get because of putting task1 and
> > cgroup at the same level in the "hierarchy". I'm curious, what kind of
> > behaviour were you expecting?
>
> That behavior matches exactly with scheduling of normal tasks and
> cgroups with default cpu.shares, but doesn't match too well with what
> I can see of the posix SCHED_RR description, which suggests all the
> SCHED_RR threads go into a single queue. I was just curious if the
> behavior my patch restored was correct, since it can't be adjusted by
> tweaking any parameters like cpu.shares.
>
Again, I really think it is the intended behaviour, and yes, real-time
group scheduling "breaks" the POSIX specification of the SCHED_{FIFO,RR}
policies intentionally (and _proudly_, as Peter would say it, am I
wrong? :-P).

Dario

--
<<This happens because I choose it to happen!>> (Raistlin Majere)
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Dario Faggioli, Ph.D, http://retis.sssup.it/people/faggioli
Senior Software Engineer, Citrix Systems R&D Ltd., Cambridge (UK)

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