mm: vmscan: do not apply pressure to slab if we are not applying pressure to zone

[linux-flexiantxendom0-natty.git] / mm / vmscan.c

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 648aab8..7f8e890 100644 (file)
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2261,7 +2261,7 @@ static bool sleeping_prematurely(pg_data_t *pgdat, int order, long remaining,
                return true;
 
        /* Check the watermark levels */
-       for (i = 0; i < pgdat->nr_zones; i++) {
+       for (i = 0; i <= classzone_idx; i++) {
                struct zone *zone = pgdat->node_zones + i;
 
                if (!populated_zone(zone))
@@ -2291,7 +2291,7 @@ static bool sleeping_prematurely(pg_data_t *pgdat, int order, long remaining,
         * must be balanced
         */
        if (order)
-               return pgdat_balanced(pgdat, balanced, classzone_idx);
+               return !pgdat_balanced(pgdat, balanced, classzone_idx);
        else
                return !all_zones_ok;
 }
@@ -2406,6 +2406,7 @@ 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;
@@ -2422,23 +2423,32 @@ 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,
-                                               lru_pages);
-                       sc.nr_reclaimed += reclaim_state->reclaimed_slab;
-                       total_scanned += sc.nr_scanned;
 
-                       if (zone->all_unreclaimable)
-                               continue;
-                       if (nr_slab == 0 &&
-                           !zone_reclaimable(zone))
-                               zone->all_unreclaimable = 1;
+                               reclaim_state->reclaimed_slab = 0;
+                               nr_slab = shrink_slab(sc.nr_scanned, GFP_KERNEL,
+                                                       lru_pages);
+                               sc.nr_reclaimed += reclaim_state->reclaimed_slab;
+                               total_scanned += sc.nr_scanned;
+
+                               if (nr_slab == 0 && !zone_reclaimable(zone))
+                                       zone->all_unreclaimable = 1;
+                       }
+
                        /*
                         * If we've done a decent amount of scanning and
                         * the reclaim ratio is low, start doing writepage
@@ -2448,6 +2458,9 @@ loop_again:
                            total_scanned > sc.nr_reclaimed + sc.nr_reclaimed / 2)
                                sc.may_writepage = 1;
 
+                       if (zone->all_unreclaimable)
+                               continue;
+
                        if (!zone_watermark_ok_safe(zone, order,
                                        high_wmark_pages(zone), end_zone, 0)) {
                                all_zones_ok = 0;