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Commit e9299f50 authored by Dave Chinner's avatar Dave Chinner Committed by Al Viro
Browse files

vmscan: add customisable shrinker batch size 



For shrinkers that have their own cond_resched* calls, having
shrink_slab break the work down into small batches is not
paticularly efficient. Add a custom batchsize field to the struct
shrinker so that shrinkers can use a larger batch size if they
desire.

A value of zero (uninitialised) means "use the default", so
behaviour is unchanged by this patch.

Signed-off-by: default avatarDave Chinner <dchinner@redhat.com>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 3567b59a

include/linux/mm.h

+1 −0
Original line number Original line Diff line number Diff line
@@ -1150,6 +1150,7 @@ struct shrink_control { 
struct shrinker {

struct shrinker {

	int (*shrink)(struct shrinker *, struct shrink_control *sc);

	int (*shrink)(struct shrinker *, struct shrink_control *sc);

	int seeks;	/* seeks to recreate an obj */

	int seeks;	/* seeks to recreate an obj */

	long batch;	/* reclaim batch size, 0 = default */





	/* These are for internal use */

	/* These are for internal use */

	struct list_head list;

	struct list_head list;

mm/vmscan.c

+6 −5
Original line number Original line Diff line number Diff line
@@ -253,6 +253,8 @@ unsigned long shrink_slab(struct shrink_control *shrink, 
		int shrink_ret = 0;

		int shrink_ret = 0;

		long nr;

		long nr;

		long new_nr;

		long new_nr;

		long batch_size = shrinker->batch ? shrinker->batch

						  : SHRINK_BATCH;





		/*

		/*

		 * copy the current shrinker scan count into a local variable

		 * copy the current shrinker scan count into a local variable
@@ -303,19 +305,18 @@ unsigned long shrink_slab(struct shrink_control *shrink, 
					nr_pages_scanned, lru_pages,

					nr_pages_scanned, lru_pages,

					max_pass, delta, total_scan);

					max_pass, delta, total_scan);





		while (total_scan >= SHRINK_BATCH) {

		while (total_scan >= batch_size) {

			long this_scan = SHRINK_BATCH;

			int nr_before;

			int nr_before;





			nr_before = do_shrinker_shrink(shrinker, shrink, 0);

			nr_before = do_shrinker_shrink(shrinker, shrink, 0);

			shrink_ret = do_shrinker_shrink(shrinker, shrink,

			shrink_ret = do_shrinker_shrink(shrinker, shrink,

							this_scan);

							batch_size);

			if (shrink_ret == -1)

			if (shrink_ret == -1)

				break;

				break;

			if (shrink_ret < nr_before)

			if (shrink_ret < nr_before)

				ret += nr_before - shrink_ret;

				ret += nr_before - shrink_ret;

			count_vm_events(SLABS_SCANNED, this_scan);

			count_vm_events(SLABS_SCANNED, batch_size);

			total_scan -= this_scan;

			total_scan -= batch_size;





			cond_resched();

			cond_resched();

		}

		}