Commit 1e7e5a90 authored by Martin Hicks's avatar Martin Hicks Committed by Linus Torvalds
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[PATCH] VM: rate limit early reclaim 



When early zone reclaim is turned on the LRU is scanned more frequently when a
zone is low on memory.  This limits when the zone reclaim can be called by
skipping the scan if another thread (either via kswapd or sync reclaim) is
already reclaiming from the zone.

Signed-off-by: default avatarMartin Hicks <mort@sgi.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 0c35bbad

include/linux/mmzone.h

+2 −0
Original line number Diff line number Diff line
@@ -149,6 +149,8 @@ struct zone { 
	 * as it fails a watermark_ok() in __alloc_pages?

	 */

	int			reclaim_pages;

	/* A count of how many reclaimers are scanning this zone */

	atomic_t		reclaim_in_progress;



	/*

	 * prev_priority holds the scanning priority for this zone.  It is

mm/page_alloc.c

+1 −0
Original line number Diff line number Diff line
@@ -1738,6 +1738,7 @@ static void __init free_area_init_core(struct pglist_data *pgdat, 
		zone->nr_scan_inactive = 0;

		zone->nr_active = 0;

		zone->nr_inactive = 0;

		atomic_set(&zone->reclaim_in_progress, -1);

		if (!size)

			continue;

mm/vmscan.c

+10 −0
Original line number Diff line number Diff line
@@ -900,7 +900,9 @@ shrink_caches(struct zone **zones, struct scan_control *sc) 
		if (zone->all_unreclaimable && sc->priority != DEF_PRIORITY)

			continue;	/* Let kswapd poll it */



		atomic_inc(&zone->reclaim_in_progress);

		shrink_zone(zone, sc);

		atomic_dec(&zone->reclaim_in_progress);

	}

}
@@ -1111,7 +1113,9 @@ scan: 
			sc.nr_reclaimed = 0;

			sc.priority = priority;

			sc.swap_cluster_max = nr_pages? nr_pages : SWAP_CLUSTER_MAX;

			atomic_inc(&zone->reclaim_in_progress);

			shrink_zone(zone, &sc);

			atomic_dec(&zone->reclaim_in_progress);

			reclaim_state->reclaimed_slab = 0;

			nr_slab = shrink_slab(sc.nr_scanned, GFP_KERNEL,

						lru_pages);
@@ -1354,9 +1358,15 @@ int zone_reclaim(struct zone *zone, unsigned int gfp_mask, unsigned int order) 
	else

		sc.swap_cluster_max = SWAP_CLUSTER_MAX;



	/* Don't reclaim the zone if there are other reclaimers active */

	if (!atomic_inc_and_test(&zone->reclaim_in_progress))

		goto out;



	shrink_zone(zone, &sc);

	total_reclaimed = sc.nr_reclaimed;



 out:

	atomic_dec(&zone->reclaim_in_progress);

	return total_reclaimed;

}

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