linux-kernel - Re: AIM7 40% regression with 2.6.26-rc1

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Date:	Wed, 7 May 2008 08:31:05 -0700
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Andi Kleen <andi@...stfloor.org>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Matthew Wilcox <matthew@....cx>,
	"Zhang, Yanmin" <yanmin_zhang@...ux.intel.com>,
	Ingo Molnar <mingo@...e.hu>,
	LKML <linux-kernel@...r.kernel.org>,
	Alexander Viro <viro@....linux.org.uk>
Subject: Re: AIM7 40% regression with 2.6.26-rc1

On Wed, 07 May 2008 16:57:52 +0200 Andi Kleen <andi@...stfloor.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?

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