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authorChristoph Lameter <clameter@engr.sgi.com>2006-03-22 00:08:22 -0800
committerLinus Torvalds <torvalds@g5.osdl.org>2006-03-22 07:54:00 -0800
commit7fb2d46d396b2491818f8e43b01049b3234e6c07 (patch)
treed5826a4d1c3b1853be20c6049311eb52f1a98360 /mm/vmscan.c
parent1742f19fa920cdd6905f0db5898524dde22ab2a4 (diff)
downloadlwn-7fb2d46d396b2491818f8e43b01049b3234e6c07.tar.gz
lwn-7fb2d46d396b2491818f8e43b01049b3234e6c07.zip
[PATCH] zone_reclaim: additional comments and cleanup
Add some comments to explain how zone reclaim works. And it fixes the following issues: - PF_SWAPWRITE needs to be set for RECLAIM_SWAP to be able to write out pages to swap. Currently RECLAIM_SWAP may not do that. - remove setting nr_reclaimed pages after slab reclaim since the slab shrinking code does not use that and the nr_reclaimed pages is just right for the intended follow up action. Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'mm/vmscan.c')
-rw-r--r--mm/vmscan.c18
1 files changed, 14 insertions, 4 deletions
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 2d5d4864de88..c712b946e4ff 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1887,6 +1887,7 @@ int zone_reclaim_interval __read_mostly = 30*HZ;
*/
static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
{
+ /* Minimum pages needed in order to stay on node */
const unsigned long nr_pages = 1 << order;
struct task_struct *p = current;
struct reclaim_state reclaim_state;
@@ -1924,9 +1925,12 @@ static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
if (nr_reclaimed < nr_pages && (zone_reclaim_mode & RECLAIM_SLAB)) {
/*
- * shrink_slab does not currently allow us to determine
- * how many pages were freed in the zone. So we just
- * shake the slab and then go offnode for a single allocation.
+ * shrink_slab() does not currently allow us to determine how
+ * many pages were freed in this zone. So we just shake the slab
+ * a bit and then go off node for this particular allocation
+ * despite possibly having freed enough memory to allocate in
+ * this zone. If we freed local memory then the next
+ * allocations will be local again.
*
* shrink_slab will free memory on all zones and may take
* a long time.
@@ -1937,8 +1941,14 @@ static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
p->reclaim_state = NULL;
current->flags &= ~(PF_MEMALLOC | PF_SWAPWRITE);
- if (nr_reclaimed == 0)
+ if (nr_reclaimed == 0) {
+ /*
+ * We were unable to reclaim enough pages to stay on node. We
+ * now allow off node accesses for a certain time period before
+ * trying again to reclaim pages from the local zone.
+ */
zone->last_unsuccessful_zone_reclaim = jiffies;
+ }
return nr_reclaimed >= nr_pages;
}