[PATCH 1/4] vmscan: change the number of the unmapped files in zone reclaim

KOSAKI Motohiro
2009-05-13T03:18:59Z

Subject: [PATCH] vmscan: change the number of the unmapped files in zone reclaim

Documentation/sysctl/vm.txt says

A percentage of the total pages in each zone. Zone reclaim will only
occur if more than this percentage of pages are file backed and unmapped.
This is to insure that a minimal amount of local pages is still available for
file I/O even if the node is overallocated.

However, zone_page_state(zone, NR_FILE_PAGES) contain some non file backed pages
(e.g. swapcache, buffer-head)

The right calculation is to use NR_{IN}ACTIVE_FILE.

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 | 21 ++++++++++++++-------
1 file changed, 14 insertions(+), 7 deletions(-)

Index: b/mm/vmscan.c
===================================================================
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2397,6 +2397,7 @@ static int __zone_reclaim(struct zone *z
.isolate_pages = isolate_pages_global,
};
unsigned long slab_reclaimable;
+ long nr_unmapped_file_pages;

disable_swap_token();
cond_resched();
@@ -2409,9 +2410,11 @@ static int __zone_reclaim(struct zone *z
reclaim_state.reclaimed_slab = 0;
p->reclaim_state = &reclaim_state;

- if (zone_page_state(zone, NR_FILE_PAGES) -
- zone_page_state(zone, NR_FILE_MAPPED) >
- zone->min_unmapped_pages) {
+ nr_unmapped_file_pages = zone_page_state(zone, NR_INACTIVE_FILE) +
+ zone_page_state(zone, NR_ACTIVE_FILE) -
+ zone_page_state(zone, NR_FILE_MAPPED);
+
+ if (nr_unmapped_file_pages > zone->min_unmapped_pages) {
/*
* Free memory by calling shrink zone with increasing
* priorities until we have enough memory freed.
@@ -2458,6 +2461,8 @@ int zone_reclaim(struct zone *zone, gfp_
{
int node_id;
int ret;
+ long nr_unmapped_file_pages;
+ long nr_slab_reclaimable;

/*
* Zone reclaim reclaims unmapped file backed pages and
@@ -2469,10 +2474,12 @@ int zone_reclaim(struct zone *zone, gfp_
* if less than a specified percentage of the zone is used by
* unmapped file backed pages.
*/
- if (zone_page_state(zone, NR_FILE_PAGES) -
- zone_page_state(zone, NR_FILE_MAPPED) <= zone->min_unmapped_pages
- && zone_page_state(zone, NR_SLAB_RECLAIMABLE)
- <= zone->min_slab_pages)
+ nr_unmapped_file_pages = zone_page_state(zone, NR_INACTIVE_FILE) +
+ zone_page_state(zone, NR_ACTIVE_FILE) -
+ zone_page_state(zone, NR_FILE_MAPPED);
+ nr_slab_reclaimable = zone_page_state(zone, NR_SLAB_RECLAIMABLE);
+ if (nr_unmapped_file_pages <= zone->min_unmapped_pages &&
+ nr_slab_reclaimable <= zone->min_slab_pages)
return 0;

if (zone_is_all_unreclaimable(zone))