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Commit 79dafcdc authored by Mel Gorman's avatar Mel Gorman Committed by Linus Torvalds
Browse files

mm, vmscan: by default have direct reclaim only shrink once per node 

Direct reclaim iterates over all zones in the zonelist and shrinking
them but this is in conflict with node-based reclaim.  In the default
case, only shrink once per node.

Link: http://lkml.kernel.org/r/1467970510-21195-11-git-send-email-mgorman@techsingularity.net


Signed-off-by: default avatarMel Gorman <mgorman@techsingularity.net>
Acked-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
Acked-by: default avatarVlastimil Babka <vbabka@suse.cz>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Rik van Riel <riel@surriel.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 38087d9b

mm/vmscan.c

+14 −8
Original line number Diff line number Diff line
@@ -2552,14 +2552,6 @@ static inline bool compaction_ready(struct zone *zone, int order, int classzone_ 
 * try to reclaim pages from zones which will satisfy the caller's allocation

 * request.

 *

 * We reclaim from a zone even if that zone is over high_wmark_pages(zone).

 * Because:

 * a) The caller may be trying to free *extra* pages to satisfy a higher-order

 *    allocation or

 * b) The target zone may be at high_wmark_pages(zone) but the lower zones

 *    must go *over* high_wmark_pages(zone) to satisfy the `incremental min'

 *    zone defense algorithm.

 *

 * If a zone is deemed to be full of pinned pages then just give it a light

 * scan then give up on it.

 */
@@ -2571,6 +2563,7 @@ static void shrink_zones(struct zonelist *zonelist, struct scan_control *sc) 
	unsigned long nr_soft_scanned;

	gfp_t orig_mask;

	enum zone_type classzone_idx;

	pg_data_t *last_pgdat = NULL;



	/*

	 * If the number of buffer_heads in the machine exceeds the maximum
@@ -2629,6 +2622,15 @@ static void shrink_zones(struct zonelist *zonelist, struct scan_control *sc) 
				continue;

			}



			/*

			 * Shrink each node in the zonelist once. If the

			 * zonelist is ordered by zone (not the default) then a

			 * node may be shrunk multiple times but in that case

			 * the user prefers lower zones being preserved.

			 */

			if (zone->zone_pgdat == last_pgdat)

				continue;



			/*

			 * This steals pages from memory cgroups over softlimit

			 * and returns the number of reclaimed pages and
@@ -2644,6 +2646,10 @@ static void shrink_zones(struct zonelist *zonelist, struct scan_control *sc) 
			/* need some check for avoid more shrink_zone() */

		}



		/* See comment about same check for global reclaim above */

		if (zone->zone_pgdat == last_pgdat)

			continue;

		last_pgdat = zone->zone_pgdat;

		shrink_node(zone->zone_pgdat, sc, classzone_idx);

	}