linux-kernel - Re: [PATCH 2/6] change alloc function in pcpu_alloc

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Date:	Tue, 20 Apr 2010 16:05:22 +0100
From:	Mel Gorman <mel@....ul.ie>
To:	Tejun Heo <tj@...nel.org>
Cc:	Christoph Lameter <cl@...ux-foundation.org>,
	Minchan Kim <minchan.kim@...il.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	Bob Liu <lliubbo@...il.com>, linux-kernel@...r.kernel.org,
	linux-mm@...ck.org
Subject: Re: [PATCH 2/6] change alloc function in pcpu_alloc_pages

On Tue, Apr 20, 2010 at 07:27:09AM +0900, Tejun Heo wrote:
> Hello, Christoph.
> 
> On 04/20/2010 02:38 AM, Christoph Lameter wrote:
> > alloc_pages_exact_node results in more confusion because it does suggest
> > that fallback to other nodes is not allowed.
> 
> I can't see why alloc_pages_exact_node() exists at all.  It's in the
> mainline and if you look at the difference between alloc_pages_node()
> and alloc_pages_exact_node(), it's almost silly.  :-(
> 

alloc_pages_exact_node() avoids a branch in a hot path that is checking for
something the caller already knows. That's the reason it exists.

-- 
Mel Gorman
Part-time Phd Student                          Linux Technology Center
University of Limerick                         IBM Dublin Software Lab
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