[PATCH 3/4] vmscan: zone_reclaim use may_swap

KOSAKI Motohiro
2009-05-13T03:19:43Z

Subject: [PATCH] vmscan: zone_reclaim use may_swap

Documentation/sysctl/vm.txt says

zone_reclaim_mode:

Zone_reclaim_mode allows someone to set more or less aggressive approaches to
reclaim memory when a zone runs out of memory. If it is set to zero then no
zone reclaim occurs. Allocations will be satisfied from other zones / nodes
in the system.

This is value ORed together of

1 = Zone reclaim on
2 = Zone reclaim writes dirty pages out
4 = Zone reclaim swaps pages

So, "(zone_reclaim_mode & RECLAIM_SWAP) == 0" mean we don't want to reclaim
swap-backed pages. not mapped file.

Thus, may_swap is better than may_unmap.

Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Rik van Riel <riel@redhat.com>
---
mm/vmscan.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

Index: b/mm/vmscan.c
===================================================================
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2387,8 +2387,8 @@ static int __zone_reclaim(struct zone *z
int priority;
struct scan_control sc = {
.may_writepage = !!(zone_reclaim_mode & RECLAIM_WRITE),
- .may_unmap = !!(zone_reclaim_mode & RECLAIM_SWAP),
- .may_swap = 1,
+ .may_unmap = 1,
+ .may_swap = !!(zone_reclaim_mode & RECLAIM_SWAP),
.swap_cluster_max = max_t(unsigned long, nr_pages,
SWAP_CLUSTER_MAX),
.gfp_mask = gfp_mask,