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authorAndy Whitcroft <apw@shadowen.org>2007-08-22 14:01:25 -0700
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-08-22 19:52:45 -0700
commite9187bdcbbc06090757d565a3077e1b0ecab23d2 (patch)
tree5393cb22c5aef33ec27fa23d633ea088a6066c13 /mm
parent0cd82ef1fb8909d6d414f36f291c2f67ca70e2be (diff)
downloadlinux-2.6.34-ux500-e9187bdcbbc06090757d565a3077e1b0ecab23d2.tar.gz
synchronous lumpy reclaim: ensure we count pages transitioning inactive via clear_active_flags
As pointed out by Mel when reclaim is applied at higher orders a significant amount of IO may be started. As this takes finite time to drain reclaim will consider more areas than ultimatly needed to satisfy the request. This leads to more reclaim than strictly required and reduced success rates. I was able to confirm Mel's test results on systems locally. These show that even under light load the success rates drop off far more than expected. Testing with a modified version of his patch (which follows) I was able to allocate almost all of ZONE_MOVABLE with a near idle system. I ran 5 test passes sequentially following system boot (the system has 29 hugepages in ZONE_MOVABLE): 2.6.23-rc1 11 8 6 7 7 sync_lumpy 28 28 29 29 26 These show that although hugely better than the near 0% success normally expected we can only allocate about a 1/4 of the zone. Using synchronous reclaim for these allocations we get close to 100% as expected. I have also run our standard high order tests and these show no regressions in allocation success rates at rest, and some significant improvements under load. This patch: We are transitioning pages from active to inactive in clear_active_flags, those need counting as PGDEACTIVATE vm events. Signed-off-by: Andy Whitcroft <apw@shadowen.org> Acked-by: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/vmscan.c1
1 files changed, 1 insertions, 0 deletions
diff --git a/mm/vmscan.c b/mm/vmscan.c
index d419e10e3da..99ec7fac33e 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -777,6 +777,7 @@ static unsigned long shrink_inactive_list(unsigned long max_scan,
(sc->order > PAGE_ALLOC_COSTLY_ORDER)?
ISOLATE_BOTH : ISOLATE_INACTIVE);
nr_active = clear_active_flags(&page_list);
+ __count_vm_events(PGDEACTIVATE, nr_active);
__mod_zone_page_state(zone, NR_ACTIVE, -nr_active);
__mod_zone_page_state(zone, NR_INACTIVE,