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Groups > linux.kernel > #1340749

[PATCH 12/27] mm: vmscan: Do not reclaim from kswapd if there is any eligible zone

From Mel Gorman <mgorman@techsingularity.net>
Newsgroups linux.kernel
Subject [PATCH 12/27] mm: vmscan: Do not reclaim from kswapd if there is any eligible zone
Date 2016-02-23 16:10 +0100
Message-ID <r5mL9-7at-49@gated-at.bofh.it> (permalink)
References <r5mL7-7at-5@gated-at.bofh.it>
Organization linux.* mail to news gateway

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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>
---
 mm/vmscan.c | 32 +++++++++++++++++++-------------
 1 file changed, 19 insertions(+), 13 deletions(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 1f5d3829d35e..39ad2ab76a2b 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -3123,24 +3123,30 @@ 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, 0)) {
+			if (!zone_balanced(zone, order, 0, classzone_idx)) {
 				classzone_idx = i;
 				break;
 			}
-- 
2.6.4

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Thread

[RFC PATCH 00/27] Move LRU page reclaim from zones to nodes v2 Mel Gorman <mgorman@techsingularity.net> - 2016-02-23 16:10 +0100
  [PATCH 06/27] mm, vmscan: Begin reclaiming pages on a per-node basis Mel Gorman <mgorman@techsingularity.net> - 2016-02-23 16:10 +0100
    Re: [PATCH 06/27] mm, vmscan: Begin reclaiming pages on a per-node  basis Johannes Weiner <hannes@cmpxchg.org> - 2016-02-23 20:00 +0100
      Re: [PATCH 06/27] mm, vmscan: Begin reclaiming pages on a per-node  basis Johannes Weiner <hannes@cmpxchg.org> - 2016-02-23 20:10 +0100
      Re: [PATCH 06/27] mm, vmscan: Begin reclaiming pages on a per-node  basis Mel Gorman <mgorman@techsingularity.net> - 2016-02-24 11:30 +0100
  [PATCH 15/27] mm, workingset: Make working set detection node-aware Mel Gorman <mgorman@techsingularity.net> - 2016-02-23 16:10 +0100
    Re: [PATCH 15/27] mm, workingset: Make working set detection  node-aware Johannes Weiner <hannes@cmpxchg.org> - 2016-02-28 17:20 +0100
  [PATCH 13/27] mm, vmscan: Make shrink_node decisions more node-centric Mel Gorman <mgorman@techsingularity.net> - 2016-02-23 16:10 +0100
  [PATCH 09/27] mm, vmscan: Simplify the logic deciding whether kswapd sleeps Mel Gorman <mgorman@techsingularity.net> - 2016-02-23 16:10 +0100
    Re: [PATCH 09/27] mm, vmscan: Simplify the logic deciding whether  kswapd sleeps Johannes Weiner <hannes@cmpxchg.org> - 2016-02-28 17:20 +0100
  [PATCH 10/27] mm, vmscan: By default have direct reclaim only shrink once per node Mel Gorman <mgorman@techsingularity.net> - 2016-02-23 16:10 +0100
    Re: [PATCH 10/27] mm, vmscan: By default have direct reclaim only  shrink once per node Johannes Weiner <hannes@cmpxchg.org> - 2016-02-28 17:20 +0100
  [PATCH 12/27] mm: vmscan: Do not reclaim from kswapd if there is any eligible zone Mel Gorman <mgorman@techsingularity.net> - 2016-02-23 16:10 +0100
  [PATCH 07/27] mm, vmscan: Have kswapd only scan based on the highest requested zone Mel Gorman <mgorman@techsingularity.net> - 2016-02-23 16:20 +0100
    Re: [PATCH 07/27] mm, vmscan: Have kswapd only scan based on the  highest requested zone Johannes Weiner <hannes@cmpxchg.org> - 2016-02-25 23:20 +0100
  [PATCH 19/27] mm: Move most file-based accounting to the node Mel Gorman <mgorman@techsingularity.net> - 2016-02-23 16:20 +0100
  [PATCH 18/27] mm: Rename NR_ANON_PAGES to NR_ANON_MAPPED Mel Gorman <mgorman@techsingularity.net> - 2016-02-23 16:20 +0100
  [PATCH 01/27] mm, page_alloc: Use ac->classzone_idx instead of zone_idx(preferred_zone) Mel Gorman <mgorman@techsingularity.net> - 2016-02-23 16:20 +0100
    Re: [PATCH 01/27] mm, page_alloc: Use ac->classzone_idx instead of  zone_idx(preferred_zone) Johannes Weiner <hannes@cmpxchg.org> - 2016-02-23 19:10 +0100
    Re: [PATCH 01/27] mm, page_alloc: Use ac->classzone_idx instead of  zone_idx(preferred_zone) Vlastimil Babka <vbabka@suse.cz> - 2016-03-03 11:40 +0100
  [PATCH 04/27] mm, vmscan: Move lru_lock to the node Mel Gorman <mgorman@techsingularity.net> - 2016-02-23 16:20 +0100
    Re: [PATCH 04/27] mm, vmscan: Move lru_lock to the node Johannes Weiner <hannes@cmpxchg.org> - 2016-02-23 19:50 +0100
  [PATCH 17/27] mm: Move page mapped accounting to the node Mel Gorman <mgorman@techsingularity.net> - 2016-02-23 16:20 +0100
  [PATCH 03/27] mm, vmstat: Add infrastructure for per-node vmstats Mel Gorman <mgorman@techsingularity.net> - 2016-02-23 16:20 +0100
    Re: [PATCH 03/27] mm, vmstat: Add infrastructure for per-node vmstats Johannes Weiner <hannes@cmpxchg.org> - 2016-02-23 19:20 +0100
      Re: [PATCH 03/27] mm, vmstat: Add infrastructure for per-node vmstats Mel Gorman <mgorman@techsingularity.net> - 2016-02-24 10:20 +0100
  [PATCH 21/27] mm, vmscan: Update classzone_idx if  buffer_heads_over_limit Mel Gorman <mgorman@techsingularity.net> - 2016-02-23 16:20 +0100
  [PATCH 11/27] mm, vmscan: Clear congestion, dirty and need for compaction on a per-node basis Mel Gorman <mgorman@techsingularity.net> - 2016-02-23 16:20 +0100
  [PATCH 16/27] mm, page_alloc: Consider dirtyable memory in terms of  nodes Mel Gorman <mgorman@techsingularity.net> - 2016-02-23 16:20 +0100
    Re: [PATCH 16/27] mm, page_alloc: Consider dirtyable memory in terms  of nodes Johannes Weiner <hannes@cmpxchg.org> - 2016-02-28 17:20 +0100
  [PATCH 20/27] mm: Move vmscan writes and file write accounting to  the node Mel Gorman <mgorman@techsingularity.net> - 2016-02-23 16:20 +0100
  [PATCH 02/27] mm, vmscan: Check if cpusets are enabled during direct reclaim Mel Gorman <mgorman@techsingularity.net> - 2016-02-23 16:20 +0100
    Re: [PATCH 02/27] mm, vmscan: Check if cpusets are enabled during  direct reclaim Johannes Weiner <hannes@cmpxchg.org> - 2016-02-23 19:10 +0100
    Re: [PATCH 02/27] mm, vmscan: Check if cpusets are enabled during  direct reclaim Vlastimil Babka <vbabka@suse.cz> - 2016-03-03 12:40 +0100
  [PATCH 27/27] mm: page_alloc: Cache the last node whose dirty limit  is reached Mel Gorman <mgorman@techsingularity.net> - 2016-02-23 16:30 +0100
  [PATCH 25/27] mm, vmscan: Add classzone information to tracepoints Mel Gorman <mgorman@techsingularity.net> - 2016-02-23 16:30 +0100
  [PATCH 23/27] mm, vmscan: Account in vmstat for pages skipped during  reclaim Mel Gorman <mgorman@techsingularity.net> - 2016-02-23 16:30 +0100
  [PATCH 22/27] mm, vmscan: Only wakeup kswapd once per node for the  requested classzone Mel Gorman <mgorman@techsingularity.net> - 2016-02-23 16:30 +0100
  [PATCH 24/27] mm: Convert zone_reclaim to node_reclaim Mel Gorman <mgorman@techsingularity.net> - 2016-02-23 16:30 +0100
  [PATCH 26/27] mm, page_alloc: Remove fair zone allocation policy Mel Gorman <mgorman@techsingularity.net> - 2016-02-23 16:30 +0100
  Re: [RFC PATCH 00/27] Move LRU page reclaim from zones to nodes v2 Christoph Lameter <cl@linux.com> - 2016-02-23 18:20 +0100
  Re: [PATCH 05/27] mm, vmscan: Move LRU lists to node Johannes Weiner <hannes@cmpxchg.org> - 2016-02-23 19:50 +0100
  Re: [RFC PATCH 00/27] Move LRU page reclaim from zones to nodes v2 Johannes Weiner <hannes@cmpxchg.org> - 2016-02-23 21:10 +0100
    Re: [RFC PATCH 00/27] Move LRU page reclaim from zones to nodes v2 Mel Gorman <mgorman@techsingularity.net> - 2016-02-23 21:20 +0100
      Re: [RFC PATCH 00/27] Move LRU page reclaim from zones to nodes v2 Johannes Weiner <hannes@cmpxchg.org> - 2016-02-23 22:00 +0100
        Re: [RFC PATCH 00/27] Move LRU page reclaim from zones to nodes v2 Mel Gorman <mgorman@techsingularity.net> - 2016-02-23 23:00 +0100
          Re: [RFC PATCH 00/27] Move LRU page reclaim from zones to nodes v2 Johannes Weiner <hannes@cmpxchg.org> - 2016-02-24 01:20 +0100
            Re: [RFC PATCH 00/27] Move LRU page reclaim from zones to nodes v2 Mel Gorman <mgorman@techsingularity.net> - 2016-02-24 11:50 +0100

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