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Commit d8c98bb6 authored by Vinayak Menon's avatar Vinayak Menon
Browse files

mm: separate out the invocation of lowmemorykiller shrinker 



The commit '6b4f77 (mm: vmscan: invoke slab shrinkers from shrink_zone())'
fixed the invocation of shrinkers but resulted in lowmemorykiller shrinker
being called more. Reduce the number of lowmemorykiller shrinker
invocations by separating out the lowmemorykiller shrinker from
shrink_slab. This will make lowmemorykiller invoked only once for all zones
reclaimed in the direct reclaim path, and once for each zone in the kswap
path. As a consequence the eligible pages passed to shrink_slab_lmk is now
the reclaimable pages of all zones. Reducing the number of lowmemorykiller
invocations reduces the unnecessary time spent in lowmemorykiller and thus
contention or failures on lowmemorykiller's scan_mutex.

Change-Id: Iaabb9e441711f1dc804980b5853b64b3f214698d
Signed-off-by: default avatarVinayak Menon <vinmenon@codeaurora.org>
parent 0293b8a7

drivers/staging/android/lowmemorykiller.c

+2 −1
Original line number Diff line number Diff line
@@ -565,7 +565,8 @@ static unsigned long lowmem_scan(struct shrinker *s, struct shrink_control *sc) 
static struct shrinker lowmem_shrinker = {

	.scan_objects = lowmem_scan,

	.count_objects = lowmem_count,

	.seeks = DEFAULT_SEEKS * 16

	.seeks = DEFAULT_SEEKS * 16,

	.flags = SHRINKER_LMK

};



static int __init lowmem_init(void)

include/linux/shrinker.h

+1 −0
Original line number Diff line number Diff line
@@ -66,6 +66,7 @@ struct shrinker { 
/* Flags */

#define SHRINKER_NUMA_AWARE	(1 << 0)

#define SHRINKER_MEMCG_AWARE	(1 << 1)

#define SHRINKER_LMK		(1 << 2)



extern int register_shrinker(struct shrinker *);

extern void unregister_shrinker(struct shrinker *);

mm/vmscan.c

+52 −2
Original line number Diff line number Diff line
@@ -399,6 +399,35 @@ static unsigned long do_shrink_slab(struct shrink_control *shrinkctl, 
	return freed;

}



static void shrink_slab_lmk(gfp_t gfp_mask, int nid,

				 struct mem_cgroup *memcg,

				 unsigned long nr_scanned,

				 unsigned long nr_eligible)

{

	struct shrinker *shrinker;



	if (nr_scanned == 0)

		nr_scanned = SWAP_CLUSTER_MAX;



	if (!down_read_trylock(&shrinker_rwsem))

		goto out;



	list_for_each_entry(shrinker, &shrinker_list, list) {

		struct shrink_control sc = {

			.gfp_mask = gfp_mask,

		};



		if (!(shrinker->flags & SHRINKER_LMK))

			continue;



		do_shrink_slab(&sc, shrinker, nr_scanned, nr_eligible);

	}



	up_read(&shrinker_rwsem);

out:

	cond_resched();

}



/**

 * shrink_slab - shrink slab caches

 * @gfp_mask: allocation context
@@ -460,6 +489,9 @@ static unsigned long shrink_slab(gfp_t gfp_mask, int nid, 
			.memcg = memcg,

		};



		if (shrinker->flags & SHRINKER_LMK)

			continue;



		if (memcg && !(shrinker->flags & SHRINKER_MEMCG_AWARE))

			continue;
@@ -2626,6 +2658,7 @@ static bool shrink_zones(struct zonelist *zonelist, struct scan_control *sc) 
	gfp_t orig_mask;

	enum zone_type requested_highidx = gfp_zone(sc->gfp_mask);

	bool reclaimable = false;

	unsigned long lru_pages = 0;



	/*

	 * If the number of buffer_heads in the machine exceeds the maximum
@@ -2653,6 +2686,7 @@ static bool shrink_zones(struct zonelist *zonelist, struct scan_control *sc) 
		 * to global LRU.

		 */

		if (global_reclaim(sc)) {

			lru_pages += zone_reclaimable_pages(zone);

			if (!cpuset_zone_allowed(zone,

						 GFP_KERNEL | __GFP_HARDWALL))

				continue;
@@ -2703,6 +2737,9 @@ static bool shrink_zones(struct zonelist *zonelist, struct scan_control *sc) 
			reclaimable = true;

	}



	if (global_reclaim(sc))

		shrink_slab_lmk(sc->gfp_mask, 0, NULL,

				sc->nr_scanned, lru_pages);

	/*

	 * Restore to original mask to avoid the impact on the caller if we

	 * promoted it to __GFP_HIGHMEM.
@@ -3181,7 +3218,8 @@ static bool prepare_kswapd_sleep(pg_data_t *pgdat, int order, long remaining, 
 */

static bool kswapd_shrink_zone(struct zone *zone,

			       int classzone_idx,

			       struct scan_control *sc)

			       struct scan_control *sc,

				unsigned long lru_pages)

{

	unsigned long balance_gap;

	bool lowmem_pressure;
@@ -3208,6 +3246,8 @@ static bool kswapd_shrink_zone(struct zone *zone, 
		return true;



	shrink_zone(zone, sc, zone_idx(zone) == classzone_idx);

	shrink_slab_lmk(sc->gfp_mask, zone_to_nid(zone), NULL,

			sc->nr_scanned, lru_pages);



	clear_bit(ZONE_WRITEBACK, &zone->flags);
@@ -3265,6 +3305,7 @@ static int balance_pgdat(pg_data_t *pgdat, int order, int classzone_idx) 


	do {

		bool raise_priority = true;

		unsigned long lru_pages = 0;



		sc.nr_reclaimed = 0;
@@ -3322,6 +3363,15 @@ static int balance_pgdat(pg_data_t *pgdat, int order, int classzone_idx) 
		if (sc.priority < DEF_PRIORITY - 2)

			sc.may_writepage = 1;



		for (i = 0; i <= end_zone; i++) {

			struct zone *zone = pgdat->node_zones + i;



			if (!populated_zone(zone))

				continue;



			lru_pages += zone_reclaimable_pages(zone);

		}



		/*

		 * Now scan the zone in the dma->highmem direction, stopping

		 * at the last zone which needs scanning.
@@ -3358,7 +3408,7 @@ static int balance_pgdat(pg_data_t *pgdat, int order, int classzone_idx) 
			 * that that high watermark would be met at 100%

			 * efficiency.

			 */

			if (kswapd_shrink_zone(zone, end_zone, &sc))

			if (kswapd_shrink_zone(zone, end_zone, &sc, lru_pages))

				raise_priority = false;

		}