From 210fe530305ee50cd889fe9250168228b2994f32 Mon Sep 17 00:00:00 2001
From: Andrew Morton <akpm@osdl.org>
Date: Fri, 6 Jan 2006 00:11:14 -0800
Subject: [PATCH] vmscan: balancing fix
Revert a patch which went into 2.6.8-rc1. The changelog for that patch was:
The shrink_zone() logic can, under some circumstances, cause far too many
pages to be reclaimed. Say, we're scanning at high priority and suddenly
hit a large number of reclaimable pages on the LRU.
Change things so we bale out when SWAP_CLUSTER_MAX pages have been
reclaimed.
Problem is, this change caused significant imbalance in inter-zone scan
balancing by truncating scans of larger zones.
Suppose, for example, ZONE_HIGHMEM is 10x the size of ZONE_NORMAL. The zone
balancing algorithm would require that if we're scanning 100 pages of
ZONE_HIGHMEM, we should scan 10 pages of ZONE_NORMAL. But this logic will
cause the scanning of ZONE_HIGHMEM to bale out after only 32 pages are
reclaimed. Thus effectively causing smaller zones to be scanned relatively
harder than large ones.
Now I need to remember what the workload was which caused me to write this
patch originally, then fix it up in a different way...
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
---
mm/vmscan.c | 8 --------
1 file changed, 8 deletions(-)
(limited to 'mm')
diff --git a/mm/vmscan.c b/mm/vmscan.c
index b2baca7645d7..5c8a412b43f4 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -63,9 +63,6 @@ struct scan_control {
unsigned long nr_mapped; /* From page_state */
- /* How many pages shrink_cache() should reclaim */
- int nr_to_reclaim;
-
/* Ask shrink_caches, or shrink_zone to scan at this priority */
unsigned int priority;
@@ -656,7 +653,6 @@ static void shrink_cache(struct zone *zone, struct scan_control *sc)
if (current_is_kswapd())
mod_page_state(kswapd_steal, nr_freed);
mod_page_state_zone(zone, pgsteal, nr_freed);
- sc->nr_to_reclaim -= nr_freed;
spin_lock_irq(&zone->lru_lock);
/*
@@ -856,8 +852,6 @@ shrink_zone(struct zone *zone, struct scan_control *sc)
else
nr_inactive = 0;
- sc->nr_to_reclaim = sc->swap_cluster_max;
-
while (nr_active || nr_inactive) {
if (nr_active) {
sc->nr_to_scan = min(nr_active,
@@ -871,8 +865,6 @@ shrink_zone(struct zone *zone, struct scan_control *sc)
(unsigned long)sc->swap_cluster_max);
nr_inactive -= sc->nr_to_scan;
shrink_cache(zone, sc);
- if (sc->nr_to_reclaim <= 0)
- break;
}
}
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