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From: Namhyung Kim <namhyung@kernel.org>
To: Mike Galbraith <efault@gmx.de>
Cc: Ingo Molnar <mingo@kernel.org>,
	Peter Zijlstra <a.p.zijlstra@chello.nl>,
	LKML <linux-kernel@vger.kernel.org>,
	Namhyung Kim <namhyung.kim@lge.com>,
	Suresh Siddha <suresh.b.siddha@intel.com>
Subject: Re: [RFC/PATCH] sched: Honor sync wake up in select_idle_sibling
Date: Fri, 10 Aug 2012 17:51:58 +0900	[thread overview]
Message-ID: <87boijw2mp.fsf@sejong.aot.lge.com> (raw)
In-Reply-To: <1344586484.4330.24.camel@marge.simpson.net> (Mike Galbraith's message of "Fri, 10 Aug 2012 10:14:44 +0200")

Hi, Mike

On Fri, 10 Aug 2012 10:14:44 +0200, Mike Galbraith wrote:
> On Fri, 2012-08-10 at 16:25 +0900, Namhyung Kim wrote: 
>> From: Namhyung Kim <namhyung.kim@lge.com>
>> 
>> When sync wakeup happens and there's the waker task running alone,
>> select the target cpu as if it's already idle.
>
> Ouch.  That defeats the purpose of select_idle_sibling().  Just because
> we're doing a sync wakeup does not mean there's no convertible overlap,
> nor that the waker is really really going to take a nap immediately.  A
> lot of the places that benefit up to and including hugely from looking
> for an idle shared cache to wake to do sync wakeups.

Thanks for the explanation! I misunderstood the function ;)

Thanks,
Namhyung


      reply	other threads:[~2012-08-10  8:57 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-08-10  7:25 Namhyung Kim
2012-08-10  8:14 ` Mike Galbraith
2012-08-10  8:51   ` Namhyung Kim [this message]

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