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authorMel Gorman <mel@csn.ul.ie>2010-05-24 17:32:27 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2010-05-25 11:06:59 -0400
commit748446bb6b5a9390b546af38ec899c868a9dbcf0 (patch)
tree4c27d0805a5e094b39ff938ad60dd270b953a79f /mm/migrate.c
parentc175a0ce7584e5b498fff8cbdb9aa7912aa9fbba (diff)
mm: compaction: memory compaction core
This patch is the core of a mechanism which compacts memory in a zone by relocating movable pages towards the end of the zone. A single compaction run involves a migration scanner and a free scanner. Both scanners operate on pageblock-sized areas in the zone. The migration scanner starts at the bottom of the zone and searches for all movable pages within each area, isolating them onto a private list called migratelist. The free scanner starts at the top of the zone and searches for suitable areas and consumes the free pages within making them available for the migration scanner. The pages isolated for migration are then migrated to the newly isolated free pages. [aarcange@redhat.com: Fix unsafe optimisation] [mel@csn.ul.ie: do not schedule work on other CPUs for compaction] Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Rik van Riel <riel@redhat.com> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Christoph Lameter <cl@linux-foundation.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/migrate.c')
-rw-r--r--mm/migrate.c11
1 files changed, 10 insertions, 1 deletions
diff --git a/mm/migrate.c b/mm/migrate.c
index 4afd6fe3c074..09e2471afa0f 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -40,7 +40,8 @@
40 40
41/* 41/*
42 * migrate_prep() needs to be called before we start compiling a list of pages 42 * migrate_prep() needs to be called before we start compiling a list of pages
43 * to be migrated using isolate_lru_page(). 43 * to be migrated using isolate_lru_page(). If scheduling work on other CPUs is
44 * undesirable, use migrate_prep_local()
44 */ 45 */
45int migrate_prep(void) 46int migrate_prep(void)
46{ 47{
@@ -55,6 +56,14 @@ int migrate_prep(void)
55 return 0; 56 return 0;
56} 57}
57 58
59/* Do the necessary work of migrate_prep but not if it involves other CPUs */
60int migrate_prep_local(void)
61{
62 lru_add_drain();
63
64 return 0;
65}
66
58/* 67/*
59 * Add isolated pages on the list back to the LRU under page lock 68 * Add isolated pages on the list back to the LRU under page lock
60 * to avoid leaking evictable pages back onto unevictable list. 69 * to avoid leaking evictable pages back onto unevictable list.