Date: Mon, 23 Jun 2014 20:47:57 +0200
From: Peter Zijlstra <peterz@infradead.org>
To: Andi Kleen <andi@firstfloor.org>
Cc: Tim Chen <tim.c.chen@linux.intel.com>, Ingo Molnar <mingo@elte.hu>,
        Michel Lespinasse <walken@google.com>, Rik van Riel <riel@redhat.com>,
        Peter Hurley <peter@hurleysoftware.com>, Jason Low <jason.low2@hp.com>,
        Davidlohr Bueson <davidlohr@hp.com>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] sched: Fast idling of CPU when system is partially
 loaded
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 <20140623162234.GP5714@two.firstfloor.org>
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On Mon, Jun 23, 2014 at 06:22:34PM +0200, Andi Kleen wrote:
> > So I don't get why we can't do the below; I think Jason tried to ask the
> > same...
> 
> The important part for performance is to minimize the cache line transfers. Your
> unconditional variant would cause more dirty cache lines than Tim's,
> right?

Don't think so. We already have the overloaded thing on stack and dirty,
and the only thing it needs is rq->nr_running and we already
unconditionally load that.
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