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From: "Rafael J. Wysocki" <rjw@sisk.pl>
To: Peter Zijlstra <a.p.zijlstra@chello.nl>
Subject: Re: [Regression] 2.6.24-git9: RT sched mishandles artswrapper (bisected)
Date: Wed, 6 Feb 2008 22:50:06 +0100
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Cc: Dmitry Adamushko <dmitry.adamushko@gmail.com>, Ingo Molnar <mingo@elte.hu>,
       Andrew Morton <akpm@linux-foundation.org>,
       LKML <linux-kernel@vger.kernel.org>,
       Steven Rostedt <rostedt@goodmis.org>
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On Wednesday, 6 of February 2008, Peter Zijlstra wrote:
> 
> On Wed, 2008-02-06 at 19:25 +0100, Rafael J. Wysocki wrote:
> > On Wednesday, 6 of February 2008, Peter Zijlstra wrote:
> > > 
> > > On Wed, 2008-02-06 at 09:40 +0100, Dmitry Adamushko wrote:
> > > > On 06/02/2008, Rafael J. Wysocki <rjw@sisk.pl> wrote:
> > > > > On Tuesday, 5 of February 2008, Dmitry Adamushko wrote:
> > > > > > Rafael, any progress with this issue? (a few questions below).
> > > > > >
> > > > > > > >
> > > > > > > > Does this artsmessage thing also run with RT priority?
> > > > > > >
> > > > > > > Well, it's in a strange state (after it's broken).  From top:
> > > > > > >
> > > > > > > PR = -51
> > > > > > > NI = 0
> > > > > > > S = R
> > > > > > > %CPU = 0.0
> > > > > > > %MEM = 0.0
> > > > > >
> > > > > > cat /proc/$PID/stat ; sleep 3; cat /proc/$PID/stat ?
> > > > > > cat /proc/sched_debug; sleep 3 ; cat /proc/sched_debug
> > > > >
> > > > > Well, instead please find appended a test program that allows me to trigger
> > > > > the issue.
> > > > 
> > > > Great, I'll look at this problem in the everning (sure, if nobody else
> > > > is faster :-).
> > > 
> > > Yeah, it seems fixed here (after I made my current queue compile for
> > > this silly CONFIG_USER_SCHED thing again).
> > > 
> > > I'm now refusing realtime tasks in groups that do not have real-time
> > > bandwidth assigned.
> > 
> > If you're referring to this patch: http://lkml.org/lkml/2008/2/4/332 , then
> > sorry, but it doesn't fix the issue for me, with the attached config.
> 
> Well, that whole queue.

It doesn't compile for me.

> Your test program just failed to obtain realtime scheduling

Well, it shouldn't.  The expected result is to obtain realtime scheduling
or we will break existing setups.

> but didn't hang. 

That's much better outcome. :-)

> I'll test your full config. 

OK, thanks.