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-rw-r--r--include/linux/swap.h9
-rw-r--r--mm/vmscan.c16
2 files changed, 22 insertions, 3 deletions
diff --git a/include/linux/swap.h b/include/linux/swap.h
index c335055c4253..ed6ebe690f4a 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -155,6 +155,15 @@ enum {
#define SWAP_CLUSTER_MAX 32
#define COMPACT_CLUSTER_MAX SWAP_CLUSTER_MAX
+/*
+ * Ratio between the present memory in the zone and the "gap" that
+ * we're allowing kswapd to shrink in addition to the per-zone high
+ * wmark, even for zones that already have the high wmark satisfied,
+ * in order to provide better per-zone lru behavior. We are ok to
+ * spend not more than 1% of the memory for this zone balancing "gap".
+ */
+#define KSWAPD_ZONE_BALANCE_GAP_RATIO 100
+
#define SWAP_MAP_MAX 0x3e /* Max duplication count, in first swap_map */
#define SWAP_MAP_BAD 0x3f /* Note pageblock is bad, in first swap_map */
#define SWAP_HAS_CACHE 0x40 /* Flag page is cached, in first swap_map */
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 665b090b6c72..060e4c191403 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2399,6 +2399,7 @@ loop_again:
for (i = 0; i <= end_zone; i++) {
struct zone *zone = pgdat->node_zones + i;
int nr_slab;
+ unsigned long balance_gap;
if (!populated_zone(zone))
continue;
@@ -2415,11 +2416,20 @@ loop_again:
mem_cgroup_soft_limit_reclaim(zone, order, sc.gfp_mask);
/*
- * We put equal pressure on every zone, unless one
- * zone has way too many pages free already.
+ * We put equal pressure on every zone, unless
+ * one zone has way too many pages free
+ * already. The "too many pages" is defined
+ * as the high wmark plus a "gap" where the
+ * gap is either the low watermark or 1%
+ * of the zone, whichever is smaller.
*/
+ balance_gap = min(low_wmark_pages(zone),
+ (zone->present_pages +
+ KSWAPD_ZONE_BALANCE_GAP_RATIO-1) /
+ KSWAPD_ZONE_BALANCE_GAP_RATIO);
if (!zone_watermark_ok_safe(zone, order,
- 8*high_wmark_pages(zone), end_zone, 0))
+ high_wmark_pages(zone) + balance_gap,
+ end_zone, 0))
shrink_zone(priority, zone, &sc);
reclaim_state->reclaimed_slab = 0;
nr_slab = shrink_slab(sc.nr_scanned, GFP_KERNEL,