From: Mike Galbraith <efault@gmx.de>
To: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>,
Ingo Molnar <mingo@elte.hu>,
Arjan van de Ven <arjan@linux.jf.intel.com>,
linux-kernel@vger.kernel.org,
Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>,
Yanmin Zhang <yanmin_zhang@linux.jf.intel.com>,
Gautham R Shenoy <ego@in.ibm.com>
Subject: Re: [patch 2/2] sched: fix select_idle_sibling() logic in select_task_rq_fair()
Date: Sat, 06 Mar 2010 09:21:55 +0100 [thread overview]
Message-ID: <1267863715.22645.12.camel@marge.simson.net> (raw)
In-Reply-To: <1267820755.6384.85.camel@marge.simson.net>
On Fri, 2010-03-05 at 21:25 +0100, Mike Galbraith wrote:
> On Fri, 2010-03-05 at 10:39 -0800, Suresh Siddha wrote:
>
> > c) Also, selelct_idle_sibling() should also treat the current cpu as an idle
> > cpu if it is a sync wakeup and we have only one task running.
>
> I'm going to have to crawl over and test the above, but this bit sounds
> like a decidedly un-good thing to do. Maybe I'm misunderstanding.
Nope, no misunderstanding. This patch does kill throughput gains. Once
awakened affine, always awaken affine is a bad idea.
I dug up my old P4 though. With it's wimpy siblings, the cost of
running two schedulers doesn't appear to be generally worth it at a
glance. You need considerable overlap to break even.
-Mike
next prev parent reply other threads:[~2010-03-06 8:22 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-03-05 18:39 [patch 1/2] sched: check for prev_cpu == this_cpu in wake_affine() Suresh Siddha
2010-03-05 18:39 ` [patch 2/2] sched: fix select_idle_sibling() logic in select_task_rq_fair() Suresh Siddha
2010-03-05 20:25 ` Mike Galbraith
2010-03-06 8:21 ` Mike Galbraith [this message]
2010-03-08 22:24 ` Suresh Siddha
2010-03-09 6:05 ` Mike Galbraith
2010-03-09 13:27 ` Mike Galbraith
2010-03-10 21:14 ` Mike Galbraith
2010-03-06 8:36 ` Mike Galbraith
2010-03-05 19:36 ` [patch 1/2] sched: check for prev_cpu == this_cpu in wake_affine() Mike Galbraith
2010-03-08 19:09 ` Suresh Siddha
2010-03-08 22:25 ` Mike Galbraith
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