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SubjectRe: [PATCH 3/6] change alloc function in alloc_slab_page
On Wed, Apr 14, 2010 at 12:25:00AM +0900, Minchan Kim wrote:
> alloc_slab_page never calls alloc_pages_node with -1.

Are you certain? What about

__kmalloc
-> slab_alloc (passed -1 as a node from __kmalloc)
-> __slab_alloc
-> new_slab
-> allocate_slab
-> alloc_slab_page

> 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@linux-foundation.org>
> Signed-off-by: Minchan Kim <minchan.kim@gmail.com>
> ---
> mm/slub.c | 2 +-
> 1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/mm/slub.c b/mm/slub.c
> index b364844..9984165 100644
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -1084,7 +1084,7 @@ static inline struct page *alloc_slab_page(gfp_t flags, int node,
> if (node == -1)
> return alloc_pages(flags, order);
> else
> - return alloc_pages_node(node, flags, order);
> + return alloc_pages_exact_node(node, flags, order);
> }
>
> static struct page *allocate_slab(struct kmem_cache *s, gfp_t flags, int node)
> --
> 1.7.0.5
>

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


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