linux-kernel - Re: [.32-rc3] scheduler: iwlagn consistently high in "waiting for CPU"

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Message-Id: <1255118780.7305.13.camel@marge.simson.net>
Date:	Fri, 09 Oct 2009 22:06:20 +0200
From:	Mike Galbraith <efault@....de>
To:	Frans Pop <elendil@...net.nl>
Cc:	Arjan van de Ven <arjan@...radead.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Ingo Molnar <mingo@...e.hu>,
	Peter Zijlstra <peterz@...radead.org>,
	linux-wireless@...r.kernel.org
Subject: Re: [.32-rc3] scheduler: iwlagn consistently high in "waiting for
 CPU"

On Fri, 2009-10-09 at 18:27 +0200, Frans Pop wrote:
> On Friday 09 October 2009, Mike Galbraith wrote:
> > sched: update the clock of runqueue select_task_rq() selected.
> >
> > In try_to_wake_up(), we update the runqueue clock, but select_task_rq()
> > may select a different runqueue than the one we updated, leaving the new
> > runqueue's clock stale for a bit.
> >
> > This patch cures occasional huge latencies reported by latencytop when
> > coming out of idle on a mostly idle NO_HZ box.
> 
> This patch (without Arjan's previous one applied) also fixes my latency 
> issues. Nice work!

Thanks for the confirmation (and kind words).

	-Mike

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