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Commit 4f588331 authored by Mel Gorman's avatar Mel Gorman Committed by Linus Torvalds
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mm, vmscan: avoid passing in classzone_idx unnecessarily to compaction_ready 

The scan_control structure has enough information available for
compaction_ready() to make a decision.  The classzone_idx manipulations
in shrink_zones() are no longer necessary as the highest populated zone
is no longer used to determine if shrink_slab should be called or not.

[mgorman@techsingularity.net remove redundant check in shrink_zones()]
  Link: http://lkml.kernel.org/r/1468588165-12461-3-git-send-email-mgorman@techsingularity.net
Link: http://lkml.kernel.org/r/1467970510-21195-26-git-send-email-mgorman@techsingularity.net


Signed-off-by: default avatarMel Gorman <mgorman@techsingularity.net>
Acked-by: default avatarHillf Danton <hillf.zj@alibaba-inc.com>
Acked-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
Acked-by: default avatarVlastimil Babka <vbabka@suse.cz>
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 970a39a3

mm/vmscan.c

+7 −20
Original line number Diff line number Diff line
@@ -2523,7 +2523,7 @@ static bool shrink_node(pg_data_t *pgdat, struct scan_control *sc) 
 * Returns true if compaction should go ahead for a high-order request, or

 * the high-order allocation would succeed without compaction.

 */

static inline bool compaction_ready(struct zone *zone, int order, int classzone_idx)

static inline bool compaction_ready(struct zone *zone, struct scan_control *sc)

{

	unsigned long watermark;

	bool watermark_ok;
@@ -2534,21 +2534,21 @@ static inline bool compaction_ready(struct zone *zone, int order, int classzone_ 
	 * there is a buffer of free pages available to give compaction

	 * a reasonable chance of completing and allocating the page

	 */

	watermark = high_wmark_pages(zone) + (2UL << order);

	watermark_ok = zone_watermark_ok_safe(zone, 0, watermark, classzone_idx);

	watermark = high_wmark_pages(zone) + (2UL << sc->order);

	watermark_ok = zone_watermark_ok_safe(zone, 0, watermark, sc->reclaim_idx);



	/*

	 * If compaction is deferred, reclaim up to a point where

	 * compaction will have a chance of success when re-enabled

	 */

	if (compaction_deferred(zone, order))

	if (compaction_deferred(zone, sc->order))

		return watermark_ok;



	/*

	 * If compaction is not ready to start and allocation is not likely

	 * to succeed without it, then keep reclaiming.

	 */

	if (compaction_suitable(zone, order, 0, classzone_idx) == COMPACT_SKIPPED)

	if (compaction_suitable(zone, sc->order, 0, sc->reclaim_idx) == COMPACT_SKIPPED)

		return false;



	return watermark_ok;
@@ -2569,7 +2569,6 @@ static void shrink_zones(struct zonelist *zonelist, struct scan_control *sc) 
	unsigned long nr_soft_reclaimed;

	unsigned long nr_soft_scanned;

	gfp_t orig_mask;

	enum zone_type classzone_idx;

	pg_data_t *last_pgdat = NULL;



	/*
@@ -2580,7 +2579,7 @@ static void shrink_zones(struct zonelist *zonelist, struct scan_control *sc) 
	orig_mask = sc->gfp_mask;

	if (buffer_heads_over_limit) {

		sc->gfp_mask |= __GFP_HIGHMEM;

		sc->reclaim_idx = classzone_idx = gfp_zone(sc->gfp_mask);

		sc->reclaim_idx = gfp_zone(sc->gfp_mask);

	}



	for_each_zone_zonelist_nodemask(zone, z, zonelist,
@@ -2588,17 +2587,6 @@ static void shrink_zones(struct zonelist *zonelist, struct scan_control *sc) 
		if (!populated_zone(zone))

			continue;



		/*

		 * Note that reclaim_idx does not change as it is the highest

		 * zone reclaimed from which for empty zones is a no-op but

		 * classzone_idx is used by shrink_node to test if the slabs

		 * should be shrunk on a given node.

		 */

		classzone_idx = sc->reclaim_idx;

		while (!populated_zone(zone->zone_pgdat->node_zones +

							classzone_idx))

			classzone_idx--;



		/*

		 * Take care memory controller reclaiming has small influence

		 * to global LRU.
@@ -2623,8 +2611,7 @@ static void shrink_zones(struct zonelist *zonelist, struct scan_control *sc) 
			 */

			if (IS_ENABLED(CONFIG_COMPACTION) &&

			    sc->order > PAGE_ALLOC_COSTLY_ORDER &&

			    zonelist_zone_idx(z) <= classzone_idx &&

			    compaction_ready(zone, sc->order, classzone_idx)) {

			    compaction_ready(zone, sc)) {

				sc->compaction_ready = true;

				continue;

			}