Re: [PATCH 29 of 66] don't alloc harder for gfp nomemalloc even if nowait

Mel Gorman
2010-11-18T13:19:33Z

On Wed, Nov 03, 2010 at 04:28:04PM +0100, Andrea Arcangeli wrote:
> From: Andrea Arcangeli <aarcange@redhat.com>
>
> Not worth throwing away the precious reserved free memory pool for allocations
> that can fail gracefully (either through mempool or because they're transhuge
> allocations later falling back to 4k allocations).
>
> Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
> Acked-by: Rik van Riel <riel@redhat.com>

Acked-by: Mel Gorman <mel@csn.ul.ie>

> ---
>
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -1941,7 +1941,12 @@ gfp_to_alloc_flags(gfp_t gfp_mask)
> alloc_flags |= (__force int) (gfp_mask & __GFP_HIGH);
>
> if (!wait) {
> - alloc_flags |= ALLOC_HARDER;
> + /*
> + * Not worth trying to allocate harder for
> + * __GFP_NOMEMALLOC even if it can't schedule.
> + */
> + if (!(gfp_mask & __GFP_NOMEMALLOC))
> + alloc_flags |= ALLOC_HARDER;
> /*
> * Ignore cpuset if GFP_ATOMIC (!wait) rather than fail alloc.
> * See also cpuset_zone_allowed() comment in kernel/cpuset.c.
>

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