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From: Peter Zijlstra <peterz@infradead.org>
To: paulmck@linux.vnet.ibm.com
Cc: Damien Wyart <damien.wyart@free.fr>, Ingo Molnar <mingo@elte.hu>,
	Mike Galbraith <efault@gmx.de>,
	linux-kernel@vger.kernel.org
Subject: Re: Very high CPU load when idle with 3.0-rc1
Date: Mon, 30 May 2011 23:33:39 +0200	[thread overview]
Message-ID: <1306791219.23844.12.camel@twins> (raw)
In-Reply-To: <20110530212833.GS2668@linux.vnet.ibm.com>

On Mon, 2011-05-30 at 14:28 -0700, Paul E. McKenney wrote:
> On Mon, May 30, 2011 at 07:19:49PM +0200, Peter Zijlstra wrote:
> > On Mon, 2011-05-30 at 09:23 -0700, Paul E. McKenney wrote:
> > >         sp.sched_priority = RCU_KTHREAD_PRIO;
> > >         sched_setscheduler_nocheck(t, SCHED_FIFO, &sp); 
> > 
> > Why are those things RT tasks anyway? The old ksoftirq runs as a regular
> > task. And once you start boosting things you can boost this into FIFO as
> > well...
> > 
> > just wondering..
> 
> Because priority boosting doesn't help unless the callbacks also run
> RT priority.
> 
> I could make it so that they ran as normal tasks if !RCU_BOOST, but
> they would still need to run as RT tasks for RCU_BOOST.  I figured
> running them the same way in both cases would be simpler.

Ah, I thought you'd boost the threads along with the waiters, to the
same prio so that they wouldn't disturb higher priority tasks for no
reason.

  reply	other threads:[~2011-05-30 21:34 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-05-30  5:59 Very high CPU load when idle with 3.0-rc1 Damien Wyart
2011-05-30 11:34 ` Peter Zijlstra
2011-05-30 12:17   ` Ingo Molnar
2011-05-30 13:10   ` Mike Galbraith
2011-05-30 16:23   ` Paul E. McKenney
2011-05-30 16:41     ` Paul E. McKenney
2011-05-30 16:47       ` Peter Zijlstra
2011-05-30 16:46     ` Peter Zijlstra
2011-05-30 21:29       ` Paul E. McKenney
2011-05-30 21:35         ` Peter Zijlstra
2011-05-31  1:45           ` Paul E. McKenney
2011-05-30 17:19     ` Peter Zijlstra
2011-05-30 21:28       ` Paul E. McKenney
2011-05-30 21:33         ` Peter Zijlstra [this message]
2011-05-31  1:45           ` Paul E. McKenney
2011-06-01 11:05             ` Peter Zijlstra
2011-06-01 14:37               ` Paul E. McKenney
2011-06-01 16:58                 ` Peter Zijlstra
2011-06-01 18:19                   ` Paul E. McKenney
2011-05-31 12:30   ` [tip:core/urgent] rcu: Cure load woes tip-bot for Peter Zijlstra
2011-05-30 11:50 ` Very high CPU load when idle with 3.0-rc1 Damien Wyart
2011-05-30 12:22 ` Morten P.D. Stevens

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