Re: [PATCH 4/6] change alloc function in vmemmap_alloc_block

[Mel Gorman]

On Wed, Apr 14, 2010 at 12:25:01AM +0900, Minchan Kim wrote:
> if node_state is N_HIGH_MEMORY, node doesn't have -1.

Also, if node_state is called with -1, a negative index is being checked in
a bitmap and that would be pretty broken in itself. I can't see a problem
with this patch.

Reviewed-by: Mel Gorman <mel@xxxxxxxxx>

> 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: Christoph Lameter <cl@xxxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Minchan Kim <minchan.kim@xxxxxxxxx>
> ---
>  mm/sparse-vmemmap.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/mm/sparse-vmemmap.c b/mm/sparse-vmemmap.c
> index 392b9bb..7710ebc 100644
> --- a/mm/sparse-vmemmap.c
> +++ b/mm/sparse-vmemmap.c
> @@ -53,7 +53,7 @@ void * __meminit vmemmap_alloc_block(unsigned long size, int node)
>  		struct page *page;
>  
>  		if (node_state(node, N_HIGH_MEMORY))
> -			page = alloc_pages_node(node,
> +			page = alloc_pages_exact_node(node,
>  				GFP_KERNEL | __GFP_ZERO, get_order(size));
>  		else
>  			page = alloc_pages(GFP_KERNEL | __GFP_ZERO,
> -- 
> 1.7.0.5
> 

-- 
Mel Gorman
Part-time Phd Student                          Linux Technology Center
University of Limerick                         IBM Dublin Software Lab
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/