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

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Date:	Thu, 15 Apr 2010 19:08:01 +0900
From:	Tejun Heo <tj@...nel.org>
To:	Minchan Kim <minchan.kim@...il.com>
CC:	Mel Gorman <mel@....ul.ie>,
	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, Christoph Lameter <cl@...ux-foundation.org>
Subject: Re: [PATCH 2/6] change alloc function in pcpu_alloc_pages

Hello,

On 04/15/2010 06:40 PM, Minchan Kim wrote:
>> I'm not an expert on that part of the kernel but isn't
>> alloc_pages_any_node() identical to alloc_pages_exact_node()?  All
> 
> alloc_pages_any_node means user allows allocated pages in any
> node(most likely current node) alloc_pages_exact_node means user
> allows allocated pages in nid node if he doesn't use __GFP_THISNODE.

Ooh, sorry, I meant alloc_pages().  What would be the difference
between alloc_pages_any_node() and alloc_pages()?

>> introducing new API just to weed out invalid usages seems like an
>> overkill.
> 
> It might be.
> 
> It think it's almost same add_to_page_cache and add_to_page_cache_locked.
> If user knows the page is already locked, he can use
> add_to_page_cache_locked for performance gain and code readability
> which we need to lock the page before calling it.

Yeah, if both APIs are necessary at the end of the conversion, sure.
I was just saying that introducing new APIs just to weed out invalid
usages and then later killing the old API would be rather excessive.

I was just wondering whether we could just clean up alloc_pages_node()
users and kill alloc_pages_exact_node().

Thanks.

-- 
tejun
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