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Date: Thu, 22 Apr 2010 19:15:14 +0900
Message-ID: <x2h28c262361004220315v9b8fbf3ei86fe0ebba92169f1@mail.gmail.com>
Subject: Re: [PATCH 2/6] change alloc function in pcpu_alloc_pages
From: Minchan Kim <minchan.kim@gmail.com>
To: Tejun Heo <tj@kernel.org>
Cc: Mel Gorman <mel@csn.ul.ie>, Christoph Lameter <cl@linux-foundation.org>,
       Andrew Morton <akpm@linux-foundation.org>,
       KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
       Bob Liu <lliubbo@gmail.com>, linux-kernel@vger.kernel.org,
       linux-mm@kvack.org
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On Wed, Apr 21, 2010 at 7:48 PM, Tejun Heo <tj@kernel.org> wrote:
> Hello,
>
> On 04/20/2010 05:05 PM, Mel Gorman wrote:
>> 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.
>
> Yeah sure but Minchan is trying to tidy up the API by converting
> alloc_pages_node() users to use alloc_pages_exact_node(), at which
> point, the distinction becomes pretty useless.  Wouldn't just making
> alloc_pages_node() do what alloc_pages_exact_node() does now and
> converting all its users be simpler?  IIRC, the currently planned
> transformation looks like the following.
>
>  alloc_pages()                  -> alloc_pages_any_node()
>  alloc_pages_node()             -> basically gonna be obsoleted by _exact_node
>  alloc_pages_exact_node()       -> gonna be used by most NUMA aware allocs
>
> So, let's just make sure no one calls alloc_pages_node() w/ -1 nid,
> kill alloc_pages_node() and rename alloc_pages_exact_node() to
> alloc_pages_node().

Yes. It was a stupid idea. I hope Mel agree this suggestion.
Thanks for careful review, Tejun.


-- 
Kind regards,
Minchan Kim
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