diff options
Diffstat (limited to 'mm/vmscan.c')
| -rw-r--r-- | mm/vmscan.c | 27 |
1 files changed, 14 insertions, 13 deletions
diff --git a/mm/vmscan.c b/mm/vmscan.c index ff2ebe9458a..5d4c4d02254 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -1503,10 +1503,6 @@ module_init(kswapd_init) * * If non-zero call zone_reclaim when the number of free pages falls below * the watermarks. - * - * In the future we may add flags to the mode. However, the page allocator - * should only have to check that zone_reclaim_mode != 0 before calling - * zone_reclaim(). */ int zone_reclaim_mode __read_mostly; @@ -1524,6 +1520,12 @@ int zone_reclaim_mode __read_mostly; #define ZONE_RECLAIM_PRIORITY 4 /* + * Percentage of pages in a zone that must be unmapped for zone_reclaim to + * occur. + */ +int sysctl_min_unmapped_ratio = 1; + +/* * Try to free up some pages from this zone through reclaim. */ static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order) @@ -1590,18 +1592,17 @@ int zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order) int node_id; /* - * Do not reclaim if there are not enough reclaimable pages in this - * zone that would satify this allocations. + * Zone reclaim reclaims unmapped file backed pages. * - * All unmapped pagecache pages are reclaimable. - * - * Both counters may be temporarily off a bit so we use - * SWAP_CLUSTER_MAX as the boundary. It may also be good to - * leave a few frequently used unmapped pagecache pages around. + * A small portion of unmapped file backed pages is needed for + * file I/O otherwise pages read by file I/O will be immediately + * thrown out if the zone is overallocated. So we do not reclaim + * 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) < SWAP_CLUSTER_MAX) - return 0; + zone_page_state(zone, NR_FILE_MAPPED) <= zone->min_unmapped_ratio) + return 0; /* * Avoid concurrent zone reclaims, do not reclaim in a zone that does |