Re: [PATCH 09/16] mm: page_alloc: Take the ALLOC_NO_WATERMARK check out of the fast path

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On Fri, Apr 18, 2014 at 03:50:36PM +0100, Mel Gorman wrote:
> ALLOC_NO_WATERMARK is set in a few cases. Always by kswapd, always for
> __GFP_MEMALLOC, sometimes for swap-over-nfs, tasks etc. Each of these cases
> are relatively rare events but the ALLOC_NO_WATERMARK check is an unlikely
> branch in the fast path.  This patch moves the check out of the fast path
> and after it has been determined that the watermarks have not been met. This
> helps the common fast path at the cost of making the slow path slower and
> hitting kswapd with a performance cost. It's a reasonable tradeoff.
> 
> Signed-off-by: Mel Gorman <mgorman@xxxxxxx>

Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx>
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