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Date: Thu, 3 May 2007 11:37:56 +0100
From: Christoph Hellwig <hch@infradead.org>
To: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Hugh Dickins <hugh@veritas.com>, Andrew Morton <akpm@linux-foundation.org>,
       linux-kernel@vger.kernel.org, linux-mm@kvack.org,
       Andrea Arcangeli <andrea@suse.de>,
       Christoph Hellwig <hch@infradead.org>
Subject: Re: 2.6.22 -mm merge plans -- vm bugfixes
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On Thu, May 03, 2007 at 11:32:23AM +1000, Nick Piggin wrote:
> The attached patch gets performance up a bit by avoiding some
> barriers and some cachelines:
> 
> G5
>          pagefault   fork          exec
> 2.6.21   1.49-1.51   164.6-170.8   741.8-760.3
> +patch   1.71-1.73   175.2-180.8   780.5-794.2
> +patch2  1.61-1.63   169.8-175.0   748.6-757.0
> 
> So that brings the fork/exec hits down to much less than 5%, and
> would likely speed up other things that lock the page, like write
> or page reclaim.

Is that every fork/exec or just under certain cicumstances?
A 5% regression on every fork/exec is not acceptable.