Commit 8e950282 authored by Mel Gorman's avatar Mel Gorman Committed by Linus Torvalds
Browse files

mm: vmscan: move direct reclaim wait_iff_congested into shrink_list 



shrink_inactive_list makes decisions on whether to stall based on the
number of dirty pages encountered.  The wait_iff_congested() call in
shrink_page_list does no such thing and it's arbitrary.

This patch moves the decision on whether to set ZONE_CONGESTED and the
wait_iff_congested call into shrink_page_list.  This keeps all the
decisions on whether to stall or not in the one place.

Signed-off-by: default avatarMel Gorman <mgorman@suse.de>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Rik van Riel <riel@redhat.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Valdis Kletnieks <Valdis.Kletnieks@vt.edu>
Cc: Zlatko Calusic <zcalusic@bitsync.net>
Cc: dormando <dormando@rydia.net>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent f7ab8db7

mm/vmscan.c

+33 −29
Original line number Diff line number Diff line
@@ -695,7 +695,9 @@ static unsigned long shrink_page_list(struct list_head *page_list, 
				      struct zone *zone,

				      struct scan_control *sc,

				      enum ttu_flags ttu_flags,

				      unsigned long *ret_nr_dirty,

				      unsigned long *ret_nr_unqueued_dirty,

				      unsigned long *ret_nr_congested,

				      unsigned long *ret_nr_writeback,

				      unsigned long *ret_nr_immediate,

				      bool force_reclaim)
@@ -1017,20 +1019,13 @@ keep: 
		VM_BUG_ON(PageLRU(page) || PageUnevictable(page));

	}



	/*

	 * Tag a zone as congested if all the dirty pages encountered were

	 * backed by a congested BDI. In this case, reclaimers should just

	 * back off and wait for congestion to clear because further reclaim

	 * will encounter the same problem

	 */

	if (nr_dirty && nr_dirty == nr_congested && global_reclaim(sc))

		zone_set_flag(zone, ZONE_CONGESTED);



	free_hot_cold_page_list(&free_pages, 1);



	list_splice(&ret_pages, page_list);

	count_vm_events(PGACTIVATE, pgactivate);

	mem_cgroup_uncharge_end();

	*ret_nr_dirty += nr_dirty;

	*ret_nr_congested += nr_congested;

	*ret_nr_unqueued_dirty += nr_unqueued_dirty;

	*ret_nr_writeback += nr_writeback;

	*ret_nr_immediate += nr_immediate;
@@ -1045,7 +1040,7 @@ unsigned long reclaim_clean_pages_from_list(struct zone *zone, 
		.priority = DEF_PRIORITY,

		.may_unmap = 1,

	};

	unsigned long ret, dummy1, dummy2, dummy3;

	unsigned long ret, dummy1, dummy2, dummy3, dummy4, dummy5;

	struct page *page, *next;

	LIST_HEAD(clean_pages);
@@ -1058,7 +1053,7 @@ unsigned long reclaim_clean_pages_from_list(struct zone *zone, 


	ret = shrink_page_list(&clean_pages, zone, &sc,

			TTU_UNMAP|TTU_IGNORE_ACCESS,

				&dummy1, &dummy2, &dummy3, true);

			&dummy1, &dummy2, &dummy3, &dummy4, &dummy5, true);

	list_splice(&clean_pages, page_list);

	__mod_zone_page_state(zone, NR_ISOLATED_FILE, -ret);

	return ret;
@@ -1352,6 +1347,8 @@ shrink_inactive_list(unsigned long nr_to_scan, struct lruvec *lruvec, 
	unsigned long nr_scanned;

	unsigned long nr_reclaimed = 0;

	unsigned long nr_taken;

	unsigned long nr_dirty = 0;

	unsigned long nr_congested = 0;

	unsigned long nr_unqueued_dirty = 0;

	unsigned long nr_writeback = 0;

	unsigned long nr_immediate = 0;
@@ -1396,7 +1393,8 @@ shrink_inactive_list(unsigned long nr_to_scan, struct lruvec *lruvec, 
		return 0;



	nr_reclaimed = shrink_page_list(&page_list, zone, sc, TTU_UNMAP,

			&nr_unqueued_dirty, &nr_writeback, &nr_immediate,

				&nr_dirty, &nr_unqueued_dirty, &nr_congested,

				&nr_writeback, &nr_immediate,

				false);



	spin_lock_irq(&zone->lru_lock);
@@ -1431,7 +1429,7 @@ shrink_inactive_list(unsigned long nr_to_scan, struct lruvec *lruvec, 
	 * same way balance_dirty_pages() manages.

	 *

	 * This scales the number of dirty pages that must be under writeback

	 * before throttling depending on priority. It is a simple backoff

	 * before a zone gets flagged ZONE_WRITEBACK. It is a simple backoff

	 * function that has the most effect in the range DEF_PRIORITY to

	 * DEF_PRIORITY-2 which is the priority reclaim is considered to be

	 * in trouble and reclaim is considered to be in trouble.
@@ -1442,18 +1440,27 @@ shrink_inactive_list(unsigned long nr_to_scan, struct lruvec *lruvec, 
	 * ...

	 * DEF_PRIORITY-6 For SWAP_CLUSTER_MAX isolated pages, throttle if any

	 *                     isolated page is PageWriteback

	 *

	 * Once a zone is flagged ZONE_WRITEBACK, kswapd will count the number

	 * of pages under pages flagged for immediate reclaim and stall if any

	 * are encountered in the nr_immediate check below.

	 */

	if (nr_writeback && nr_writeback >=

			(nr_taken >> (DEF_PRIORITY - sc->priority))) {

			(nr_taken >> (DEF_PRIORITY - sc->priority)))

		zone_set_flag(zone, ZONE_WRITEBACK);

		wait_iff_congested(zone, BLK_RW_ASYNC, HZ/10);

	}



	/*

	 * memcg will stall in page writeback so only consider forcibly

	 * stalling for global reclaim

	 */

	if (global_reclaim(sc)) {

		/*

		 * Tag a zone as congested if all the dirty pages scanned were

		 * backed by a congested BDI and wait_iff_congested will stall.

		 */

		if (nr_dirty && nr_dirty == nr_congested)

			zone_set_flag(zone, ZONE_CONGESTED);



		/*

		 * If dirty pages are scanned that are not queued for IO, it

		 * implies that flushers are not keeping up. In this case, flag
@@ -1474,6 +1481,14 @@ shrink_inactive_list(unsigned long nr_to_scan, struct lruvec *lruvec, 
			congestion_wait(BLK_RW_ASYNC, HZ/10);

	}



	/*

	 * Stall direct reclaim for IO completions if underlying BDIs or zone

	 * is congested. Allow kswapd to continue until it starts encountering

	 * unqueued dirty pages or cycling through the LRU too quickly.

	 */

	if (!sc->hibernation_mode && !current_is_kswapd())

		wait_iff_congested(zone, BLK_RW_ASYNC, HZ/10);



	trace_mm_vmscan_lru_shrink_inactive(zone->zone_pgdat->node_id,

		zone_idx(zone),

		nr_scanned, nr_reclaimed,
@@ -2374,17 +2389,6 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist, 
						WB_REASON_TRY_TO_FREE_PAGES);

			sc->may_writepage = 1;

		}



		/* Take a nap, wait for some writeback to complete */

		if (!sc->hibernation_mode && sc->nr_scanned &&

		    sc->priority < DEF_PRIORITY - 2) {

			struct zone *preferred_zone;



			first_zones_zonelist(zonelist, gfp_zone(sc->gfp_mask),

						&cpuset_current_mems_allowed,

						&preferred_zone);

			wait_iff_congested(preferred_zone, BLK_RW_ASYNC, HZ/10);

		}

	} while (--sc->priority >= 0);



out:

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