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Date: Wed, 7 May 2008 08:31:05 -0700
From: Andrew Morton <akpm@linux-foundation.org>
To: Andi Kleen <andi@firstfloor.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
       Matthew Wilcox <matthew@wil.cx>,
       "Zhang, Yanmin" <yanmin_zhang@linux.intel.com>,
       Ingo Molnar <mingo@elte.hu>, LKML <linux-kernel@vger.kernel.org>,
       Alexander Viro <viro@ftp.linux.org.uk>
Subject: Re: AIM7 40% regression with 2.6.26-rc1
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On Wed, 07 May 2008 16:57:52 +0200 Andi Kleen <andi@firstfloor.org> wrote:

> Or figure out what made the semaphore consolidation slower? As Ingo
> pointed out earlier 40% is unlikely to be a fast path problem, but some
> algorithmic problem. Surely that is fixable (even for .26)?

Absolutely.  Yanmin is apparently showing that each call to __down()
results in 1,451 calls to schedule().  wtf?