linux-kernel - Re: [PATCH 5/6] change alloc function in __vmalloc_area

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Message-Id: <20100414092209.4327e545.kamezawa.hiroyu@jp.fujitsu.com>
Date:	Wed, 14 Apr 2010 09:22:09 +0900
From:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
To:	Minchan Kim <minchan.kim@...il.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Mel Gorman <mel@....ul.ie>, Bob Liu <lliubbo@...il.com>,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	Nick Piggin <npiggin@...e.de>
Subject: Re: [PATCH 5/6] change alloc function in __vmalloc_area_node

On Wed, 14 Apr 2010 00:25:02 +0900
Minchan Kim <minchan.kim@...il.com> wrote:

> __vmalloc_area_node never pass -1 to alloc_pages_node.
> It means node's validity check is unnecessary.
> So we can use alloc_pages_exact_node instead of alloc_pages_node.
> It could avoid comparison and branch as 6484eb3e2a81807722 tried.
> 
> Cc: Nick Piggin <npiggin@...e.de>
> Signed-off-by: Minchan Kim <minchan.kim@...il.com>

Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>

But, in another thinking,

-	if (node < 0)
-		page = alloc_page(gfp_mask);

may be better ;)

Thanks,
-Kame

> ---
>  mm/vmalloc.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> index ae00746..7abf423 100644
> --- a/mm/vmalloc.c
> +++ b/mm/vmalloc.c
> @@ -1499,7 +1499,7 @@ static void *__vmalloc_area_node(struct vm_struct *area, gfp_t gfp_mask,
>  		if (node < 0)
>  			page = alloc_page(gfp_mask);
>  		else
> -			page = alloc_pages_node(node, gfp_mask, 0);
> +			page = alloc_pages_exact_node(node, gfp_mask, 0);
>  
>  		if (unlikely(!page)) {
>  			/* Successfully allocated i pages, free them in __vunmap() */
> -- 
> 1.7.0.5
> 
> 

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