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From: Mel Gorman <mgorman@techsingularity.net>
To: Andrew Morton <akpm@linux-foundation.org>, Linux-MM <linux-mm@kvack.org>
Cc: Rik van Riel <riel@surriel.com>, Vlastimil Babka <vbabka@suse.cz>,
	Johannes Weiner <hannes@cmpxchg.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Mel Gorman <mgorman@techsingularity.net>
Subject: [PATCH 11/27] mm: vmscan: Do not reclaim from kswapd if there is any eligible zone
Date: Tue, 21 Jun 2016 15:15:50 +0100	[thread overview]
Message-ID: <1466518566-30034-12-git-send-email-mgorman@techsingularity.net> (raw)
In-Reply-To: <1466518566-30034-1-git-send-email-mgorman@techsingularity.net>

kswapd scans from highest to lowest for a zone that requires balancing.
This was necessary when reclaim was per-zone to fairly age pages on
lower zones. Now that we are reclaiming on a per-node basis, any eligible
zone can be used and pages will still be aged fairly. This patch avoids
reclaiming excessively unless buffer_heads are over the limit and it's
necessary to reclaim from a higher zone than requested by the waker of
kswapd to relieve low memory pressure.

Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
---
 mm/vmscan.c | 32 +++++++++++++++++++-------------
 1 file changed, 19 insertions(+), 13 deletions(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 8347406c75fa..d42a86e603e8 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -3132,24 +3132,30 @@ static int balance_pgdat(pg_data_t *pgdat, int order, int classzone_idx)
 
 		sc.nr_reclaimed = 0;
 
-		/* Scan from the highest requested zone to dma */
+		/*
+		 * If the number of buffer_heads in the machine exceeds the
+		 * maximum allowed level and this node has a highmem zone,
+		 * force kswapd to reclaim from it to relieve lowmem pressure.
+		 */
+		if (buffer_heads_over_limit) {
+			for (i = MAX_NR_ZONES - 1; i >= 0; i--) {
+				zone = pgdat->node_zones + i;
+				if (!populated_zone(zone))
+					continue;
+
+				if (is_highmem_idx(i))
+					classzone_idx = i;
+				break;
+			}
+		}
+
+		/* Only reclaim if there are no eligible zones */
 		for (i = classzone_idx; i >= 0; i--) {
 			zone = pgdat->node_zones + i;
 			if (!populated_zone(zone))
 				continue;
 
-			/*
-			 * If the number of buffer_heads in the machine
-			 * exceeds the maximum allowed level and this node
-			 * has a highmem zone, force kswapd to reclaim from
-			 * it to relieve lowmem pressure.
-			 */
-			if (buffer_heads_over_limit && is_highmem_idx(i)) {
-				classzone_idx = i;
-				break;
-			}
-
-			if (!zone_balanced(zone, order, 0)) {
+			if (!zone_balanced(zone, sc.order, classzone_idx)) {
 				classzone_idx = i;
 				break;
 			}
-- 
2.6.4

  parent reply	other threads:[~2016-06-21 14:18 UTC|newest]

Thread overview: 65+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-06-21 14:15 [PATCH 00/27] Move LRU page reclaim from zones to nodes v7 Mel Gorman
2016-06-21 14:15 ` [PATCH 01/27] mm, vmstat: Add infrastructure for per-node vmstats Mel Gorman
2016-06-21 14:15 ` [PATCH 02/27] mm, vmscan: Move lru_lock to the node Mel Gorman
2016-06-21 14:15 ` [PATCH 03/27] mm, vmscan: Move LRU lists to node Mel Gorman
2016-06-22 12:50   ` Vlastimil Babka
2016-06-21 14:15 ` [PATCH 04/27] mm, vmscan: Begin reclaiming pages on a per-node basis Mel Gorman
2016-06-22 14:04   ` Vlastimil Babka
2016-06-22 16:00     ` Vlastimil Babka
2016-06-23 11:07       ` Mel Gorman
2016-06-23 11:13         ` Michal Hocko
2016-06-23 10:58     ` Mel Gorman
2016-06-21 14:15 ` [PATCH 05/27] mm, vmscan: Have kswapd only scan based on the highest requested zone Mel Gorman
2016-06-21 14:15 ` [PATCH 06/27] mm, vmscan: Make kswapd reclaim in terms of nodes Mel Gorman
2016-06-21 14:15 ` [PATCH 07/27] mm, vmscan: Remove balance gap Mel Gorman
2016-06-21 14:15 ` [PATCH 08/27] mm, vmscan: Simplify the logic deciding whether kswapd sleeps Mel Gorman
2016-06-22 15:30   ` Vlastimil Babka
2016-06-21 14:15 ` [PATCH 09/27] mm, vmscan: By default have direct reclaim only shrink once per node Mel Gorman
2016-06-21 14:15 ` [PATCH 10/27] mm, vmscan: Remove duplicate logic clearing node congestion and dirty state Mel Gorman
2016-06-21 14:15 ` Mel Gorman [this message]
2016-06-21 14:15 ` [PATCH 12/27] mm, vmscan: Make shrink_node decisions more node-centric Mel Gorman
2016-06-22 13:20   ` Michal Hocko
2016-06-22 15:42   ` Vlastimil Babka
2016-06-21 14:15 ` [PATCH 13/27] mm, memcg: Move memcg limit enforcement from zones to nodes Mel Gorman
2016-06-22 13:15   ` Michal Hocko
2016-06-21 14:15 ` [PATCH 14/27] mm, workingset: Make working set detection node-aware Mel Gorman
2016-06-21 14:15 ` [PATCH 15/27] mm, page_alloc: Consider dirtyable memory in terms of nodes Mel Gorman
2016-06-22 14:15   ` Michal Hocko
2016-06-22 14:27     ` Michal Hocko
2016-06-23 12:53       ` Mel Gorman
2016-06-23 13:13         ` Michal Hocko
2016-06-21 14:15 ` [PATCH 16/27] mm: Move page mapped accounting to the node Mel Gorman
2016-06-21 22:32   ` Andrew Morton
2016-06-23  8:35     ` Mel Gorman
2016-06-22 14:35   ` Michal Hocko
2016-06-21 14:15 ` [PATCH 17/27] mm: Rename NR_ANON_PAGES to NR_ANON_MAPPED Mel Gorman
2016-06-22 14:28   ` Michal Hocko
2016-06-21 14:15 ` [PATCH 18/27] mm: Move most file-based accounting to the node Mel Gorman
2016-06-22 14:38   ` Michal Hocko
2016-06-21 14:15 ` [PATCH 19/27] mm: Move vmscan writes and file write " Mel Gorman
2016-06-22 14:40   ` Michal Hocko
2016-06-23 13:57     ` Mel Gorman
2016-06-23 14:06       ` Vlastimil Babka
2016-06-23 16:03         ` Mel Gorman
2016-06-21 14:15 ` [PATCH 20/27] mm, vmscan: Update classzone_idx if buffer_heads_over_limit Mel Gorman
2016-06-22 14:49   ` Michal Hocko
2016-06-21 14:16 ` [PATCH 21/27] mm, vmscan: Only wakeup kswapd once per node for the requested classzone Mel Gorman
2016-06-22 16:08   ` Vlastimil Babka
2016-06-21 14:16 ` [PATCH 22/27] mm: Convert zone_reclaim to node_reclaim Mel Gorman
2016-06-21 14:16 ` [PATCH 23/27] mm, vmscan: Add classzone information to tracepoints Mel Gorman
2016-06-21 14:16 ` [PATCH 24/27] mm, page_alloc: Remove fair zone allocation policy Mel Gorman
2016-06-21 14:16 ` [PATCH 25/27] mm: page_alloc: Cache the last node whose dirty limit is reached Mel Gorman
2016-06-21 14:16 ` [PATCH 26/27] mm: vmstat: Replace __count_zone_vm_events with a zone id equivalent Mel Gorman
2016-06-21 14:16 ` [PATCH 27/27] mm: vmstat: Account per-zone stalls and pages skipped during reclaim Mel Gorman
2016-06-23 10:26 ` [PATCH 00/27] Move LRU page reclaim from zones to nodes v7 Mel Gorman
2016-06-23 11:27   ` Michal Hocko
2016-06-23 12:33     ` Mel Gorman
2016-06-23 12:44       ` Michal Hocko
2016-06-23 21:45   ` Andrew Morton
2016-06-24  6:35 ` Balbir Singh
2016-06-24  7:50   ` Mel Gorman
2016-06-27 12:48     ` Balbir Singh
  -- strict thread matches above, loose matches on Subject: below --
2016-06-09 18:04 [PATCH 00/27] Move LRU page reclaim from zones to nodes v6 Mel Gorman
2016-06-09 18:04 ` [PATCH 11/27] mm: vmscan: Do not reclaim from kswapd if there is any eligible zone Mel Gorman
2016-06-16 10:08   ` Vlastimil Babka
2016-04-15  9:13 [PATCH 00/27] Move LRU page reclaim from zones to nodes v5 Mel Gorman
2016-04-15  9:13 ` [PATCH 11/27] mm: vmscan: Do not reclaim from kswapd if there is any eligible zone Mel Gorman
2016-04-06 11:19 [RFC PATCH 00/27] Move LRU page reclaim from zones to nodes v3 Mel Gorman
2016-04-06 11:20 ` [PATCH 11/27] mm: vmscan: Do not reclaim from kswapd if there is any eligible zone Mel Gorman

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