From: Mel Gorman <mgorman@techsingularity.net>
To: 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 12/27] mm: vmscan: Do not reclaim from kswapd if there is any eligible zone
Date: Tue, 23 Feb 2016 13:45:01 +0000 [thread overview]
Message-ID: <1456235116-32385-13-git-send-email-mgorman@techsingularity.net> (raw)
In-Reply-To: <1456235116-32385-1-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>
---
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
next prev parent reply other threads:[~2016-02-23 13:48 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-23 13:44 [RFC PATCH 00/27] Move LRU page reclaim from zones to nodes v2 Mel Gorman
2016-02-23 13:44 ` [PATCH 01/27] mm, page_alloc: Use ac->classzone_idx instead of zone_idx(preferred_zone) Mel Gorman
2016-02-23 13:44 ` [PATCH 02/27] mm, vmscan: Check if cpusets are enabled during direct reclaim Mel Gorman
2016-02-23 13:44 ` [PATCH 03/27] mm, vmstat: Add infrastructure for per-node vmstats Mel Gorman
2016-02-23 13:44 ` [PATCH 04/27] mm, vmscan: Move lru_lock to the node Mel Gorman
2016-02-23 13:44 ` [PATCH 05/27] mm, vmscan: Move LRU lists to node Mel Gorman
2016-02-23 13:44 ` [PATCH 06/27] mm, vmscan: Begin reclaiming pages on a per-node basis Mel Gorman
2016-02-23 13:44 ` [PATCH 07/27] mm, vmscan: Have kswapd only scan based on the highest requested zone Mel Gorman
2016-02-23 13:44 ` [PATCH 08/27] mm, vmscan: Make kswapd reclaim in terms of nodes Mel Gorman
2016-02-23 13:44 ` [PATCH 09/27] mm, vmscan: Simplify the logic deciding whether kswapd sleeps Mel Gorman
2016-02-23 13:44 ` [PATCH 10/27] mm, vmscan: By default have direct reclaim only shrink once per node Mel Gorman
2016-02-23 13:45 ` [PATCH 11/27] mm, vmscan: Clear congestion, dirty and need for compaction on a per-node basis Mel Gorman
2016-02-23 13:45 ` Mel Gorman [this message]
2016-02-23 13:45 ` [PATCH 13/27] mm, vmscan: Make shrink_node decisions more node-centric Mel Gorman
2016-02-23 13:45 ` [PATCH 14/27] mm, memcg: Move memcg limit enforcement from zones to nodes Mel Gorman
2016-02-23 13:45 ` [PATCH 15/27] mm, workingset: Make working set detection node-aware Mel Gorman
2016-02-23 15:04 [RFC PATCH 00/27] Move LRU page reclaim from zones to nodes v2 Mel Gorman
2016-02-23 15:04 ` [PATCH 12/27] mm: vmscan: Do not reclaim from kswapd if there is any eligible zone Mel Gorman
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