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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 06/27] mm, vmscan: Have kswapd only scan based on the highest requested zone
Date: Wed,  6 Apr 2016 12:20:05 +0100	[thread overview]
Message-ID: <1459941626-3290-7-git-send-email-mgorman@techsingularity.net> (raw)
In-Reply-To: <1459941626-3290-1-git-send-email-mgorman@techsingularity.net>

kswapd checks all eligible zones to see if they need balancing even if it was
woken for a lower zone. This made sense when we reclaimed on a per-zone basis
because we wanted to shrink zones fairly so avoid age-inversion problems.
Ideally this is completely unnecessary when reclaiming on a per-node basis.
In theory, there may still be anomalies when all requests are for lower
zones and very old pages are preserved in higher zones but this should be
the exceptional case.

Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
---
 mm/vmscan.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 0f8dc3488f9d..f2534e8f8527 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -3208,11 +3208,8 @@ static int balance_pgdat(pg_data_t *pgdat, int order, int classzone_idx)
 
 		sc.nr_reclaimed = 0;
 
-		/*
-		 * Scan in the highmem->dma direction for the highest
-		 * zone which needs scanning
-		 */
-		for (i = pgdat->nr_zones - 1; i >= 0; i--) {
+		/* Scan from the highest requested zone to dma */
+		for (i = classzone_idx; i >= 0; i--) {
 			struct zone *zone = pgdat->node_zones + i;
 
 			if (!populated_zone(zone))
-- 
2.6.4

  parent reply	other threads:[~2016-04-06 11:21 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
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 01/27] mm, page_alloc: Use ac->classzone_idx instead of zone_idx(preferred_zone) Mel Gorman
2016-04-06 11:20 ` [PATCH 02/27] mm, vmstat: Add infrastructure for per-node vmstats Mel Gorman
2016-04-06 11:20 ` [PATCH 03/27] mm, vmscan: Move lru_lock to the node Mel Gorman
2016-04-06 11:20 ` [PATCH 04/27] mm, vmscan: Move LRU lists to node Mel Gorman
2016-04-06 11:20 ` [PATCH 05/27] mm, vmscan: Begin reclaiming pages on a per-node basis Mel Gorman
2016-04-06 11:20 ` Mel Gorman [this message]
2016-04-06 11:20 ` [PATCH 07/27] mm, vmscan: Make kswapd reclaim in terms of nodes Mel Gorman
2016-04-06 11:20 ` [PATCH 08/27] mm, vmscan: Simplify the logic deciding whether kswapd sleeps Mel Gorman
2016-04-06 11:20 ` [PATCH 09/27] mm, vmscan: By default have direct reclaim only shrink once per node Mel Gorman
2016-04-06 11:20 ` [PATCH 10/27] mm, vmscan: Clear congestion, dirty and need for compaction on a per-node basis 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
2016-04-06 11:20 ` [PATCH 12/27] mm, vmscan: Make shrink_node decisions more node-centric Mel Gorman
2016-04-06 11:20 ` [PATCH 13/27] mm, memcg: Move memcg limit enforcement from zones to nodes Mel Gorman
2016-04-06 11:20 ` [PATCH 14/27] mm, workingset: Make working set detection node-aware Mel Gorman
2016-04-06 11:20 ` [PATCH 15/27] mm, page_alloc: Consider dirtyable memory in terms of nodes Mel Gorman
2016-04-06 11:20 ` [PATCH 16/27] mm: Move page mapped accounting to the node Mel Gorman
2016-04-06 11:20 ` [PATCH 17/27] mm: Rename NR_ANON_PAGES to NR_ANON_MAPPED Mel Gorman
2016-04-06 11:20 ` [PATCH 18/27] mm: Move most file-based accounting to the node Mel Gorman
2016-04-06 11:20 ` [PATCH 19/27] mm: Move vmscan writes and file write " Mel Gorman
2016-04-06 11:20 ` [PATCH 20/27] mm, vmscan: Update classzone_idx if buffer_heads_over_limit Mel Gorman
2016-04-06 11:20 ` [PATCH 21/27] mm, vmscan: Only wakeup kswapd once per node for the requested classzone Mel Gorman

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