Re: [PATCH 07/11] mm: page allocator: Do not call direct reclaimfor THP allocations while compaction is deferred

[Rik van Riel]

On 12/14/2011 10:41 AM, Mel Gorman wrote:
> If compaction is deferred, direct reclaim is used to try free enough
> pages for the allocation to succeed. For small high-orders, this has
> a reasonable chance of success. However, if the caller has specified
> __GFP_NO_KSWAPD to limit the disruption to the system, it makes more
> sense to fail the allocation rather than stall the caller in direct
> reclaim. This patch skips direct reclaim if compaction is deferred
> and the caller specifies __GFP_NO_KSWAPD.
>
> Async compaction only considers a subset of pages so it is possible for
> compaction to be deferred prematurely and not enter direct reclaim even
> in cases where it should. To compensate for this, this patch also defers
> compaction only if sync compaction failed.
>
> Signed-off-by: Mel Gorman<mgorman@xxxxxxx>
> Acked-by: Minchan Kim<minchan.kim@xxxxxxxxx>

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

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