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Date: Fri, 20 Apr 2007 13:03:22 -0700
From: William Lee Irwin III <wli@holomorphy.com>
To: Christoph Lameter <clameter@sgi.com>
Cc: Ingo Molnar <mingo@elte.hu>, linux-kernel@vger.kernel.org,
       Linus Torvalds <torvalds@linux-foundation.org>,
       Andrew Morton <akpm@linux-foundation.org>,
       Con Kolivas <kernel@kolivas.org>, Nick Piggin <npiggin@suse.de>,
       Mike Galbraith <efault@gmx.de>, Arjan van de Ven <arjan@infradead.org>,
       Peter Williams <pwil3058@bigpond.net.au>,
       Thomas Gleixner <tglx@linutronix.de>, caglar@pardus.org.tr,
       Willy Tarreau <w@1wt.eu>, Gene Heskett <gene.heskett@gmail.com>
Subject: Re: [patch] CFS scheduler, v3
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On Fri, 20 Apr 2007, William Lee Irwin III wrote:
>> I'm not really convinced it's all that worthwhile of an optimization,
>> essentially for the same reasons as you, but presumably there's a
>> benchmark result somewhere that says it matters. I've just not seen it.

On Fri, Apr 20, 2007 at 12:44:55PM -0700, Christoph Lameter wrote:
> If it is true that we frequently remotely write the per cpu runqueue 
> data then we may have a NUMA scalability issue.

>>From the discussion on Suresh's thread, it appears to have sped up a
database benchmark 0.5%.

Last I checked it was workload-dependent, but there were things that
hammer it. I mostly know of the remote wakeup issue, but there could
be other things besides wakeups that do it, too.


-- wli