Re: [PATCH 07/17] mm: page_alloc: Take the ALLOC_NO_WATERMARK check out of the fast path

[Rik van Riel]

On 05/01/2014 04:44 AM, 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>

Reviewed-by: Rik van Riel <riel@xxxxxxxxxx>

-- 
All rights reversed
--
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/