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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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