mm, vmscan: only wakeup kswapd once per node for the requested classzone (e1a55637) · Commits · 戴 / test

kswapd is woken when zones are below the low watermark but the wakeup decision is not taking the classzone into account. Now that reclaim is node-based, it is only required to wake kswapd once per node and only if all zones are unbalanced for the requested classzone. Note that one node might be checked multiple times if the zonelist is ordered by node because there is no cheap way of tracking what nodes have already been visited. For zone-ordering, each node should be checked only once. Link: http://lkml.kernel.org/r/1467970510-21195-22-git-send-email-mgorman@techsingularity.net Signed-off-by:

Mel Gorman <mgorman@techsingularity.net> Acked-by:

Vlastimil Babka <vbabka@suse.cz> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by:

Johannes Weiner <hannes@cmpxchg.org> 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:

Andrew Morton <akpm@linux-foundation.org> Signed-off-by:

Linus Torvalds <torvalds@linux-foundation.org>

mm/page_alloc.c

+6 −2

Original line number	Diff line number	Diff line
		@@ -3367,10 +3367,14 @@ static void wake_all_kswapds(unsigned int order, const struct alloc_context *ac)
		{
		struct zoneref *z;
		struct zone *zone;
		pg_data_t *last_pgdat = NULL;

		for_each_zone_zonelist_nodemask(zone, z, ac->zonelist,
		ac->high_zoneidx, ac->nodemask)
		ac->high_zoneidx, ac->nodemask) {
		if (last_pgdat != zone->zone_pgdat)
		wakeup_kswapd(zone, order, ac_classzone_idx(ac));
		last_pgdat = zone->zone_pgdat;
		}
		}

		static inline unsigned int

mm/vmscan.c

+11 −2

Original line number	Diff line number	Diff line
		@@ -3421,6 +3421,7 @@ kswapd_try_sleep:
		void wakeup_kswapd(struct zone *zone, int order, enum zone_type classzone_idx)
		{
		pg_data_t *pgdat;
		int z;

		if (!populated_zone(zone))
		return;
		@@ -3432,8 +3433,16 @@ void wakeup_kswapd(struct zone *zone, int order, enum zone_type classzone_idx)
		pgdat->kswapd_order = max(pgdat->kswapd_order, order);
		if (!waitqueue_active(&pgdat->kswapd_wait))
		return;
		if (zone_balanced(zone, order, 0))

		/* Only wake kswapd if all zones are unbalanced */
		for (z = 0; z <= classzone_idx; z++) {
		zone = pgdat->node_zones + z;
		if (!populated_zone(zone))
		continue;

		if (zone_balanced(zone, order, classzone_idx))
		return;
		}

		trace_mm_vmscan_wakeup_kswapd(pgdat->node_id, zone_idx(zone), order);
		wake_up_interruptible(&pgdat->kswapd_wait);

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