Subject: Re: [patch] Re: autogroup: sched_setscheduler() fails
From: Mike Galbraith <efault@gmx.de>
To: torbenh <torbenh@gmx.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>,
        Yong Zhang <yong.zhang0@gmail.com>, bharata@linux.vnet.ibm.com,
        Ingo Molnar <mingo@elte.hu>, linux-kernel@vger.kernel.org
In-Reply-To: <20110215154612.GI3055@siel.b>
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Date: Tue, 15 Feb 2011 17:43:30 +0100
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On Tue, 2011-02-15 at 16:46 +0100, torbenh wrote:
> On Mon, Jan 17, 2011 at 02:16:00PM +0100, Peter Zijlstra wrote:
> > On Thu, 2011-01-13 at 04:54 +0100, Mike Galbraith wrote:
> > > sched, autogroup: fix CONFIG_RT_GROUP_SCHED sched_setscheduler() failure.
> > > 
> > > If CONFIG_RT_GROUP_SCHED is set, __sched_setscheduler() fails due to autogroup
> > > not allocating rt_runtime.  Free unused/unusable rt_se and rt_rq, redirect RT
> > > tasks to the root task group, and tell __sched_setscheduler() that it's ok.
> > > 
> > > Signed-off-by: Mike Galbraith <efault@gmx.de>
> > > Reported-by: Bharata B Rao <bharata@linux.vnet.ibm.com>
> > 
> > Thanks, applied!
> 
> while this behaviour is certeinly necessary, i think this is a hack.
> it fixes the problem for autogroups.
> But its not fixed for things which want to control the cfs shares via
> normal cgroups.

You mean automated control ala systemd?  For a static set of groups, it
works fine.  I was wondering how systemd would deal with it.

> why isnt rt_runtime_us residing in a separate (new) subsystem ?

The allocation problem was shamelessly punted back to the user, where I
think it truly belongs.

	-Mike

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