Re: [patch] mm, thp: restructure thp avoidance of light synchronous migration

From: Mel Gorman
Date: Fri Jul 25 2014 - 11:39:14 EST

On Thu, Jul 24, 2014 at 03:41:06PM -0700, David Rientjes wrote:
> __GFP_NO_KSWAPD, once the way to determine if an allocation was for thp or not,
> has gained more users. Their use is not necessarily wrong, they are trying to
> do a memory allocation that can easily fail without disturbing kswapd, so the
> bit has gained additional usecases.
> This restructures the check to determine whether MIGRATE_SYNC_LIGHT should be
> used for memory compaction in the page allocator. Rather than testing solely
> for __GFP_NO_KSWAPD, test for all bits that must be set for thp allocations.
> This also moves the check to be done only after the page allocator is aborted
> for deferred or contended memory compaction since setting migration_mode for
> this case is pointless.
> Signed-off-by: David Rientjes <rientjes@xxxxxxxxxx>

Acked-by: Mel Gorman <mgorman@xxxxxxx>

Mel Gorman
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