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-rw-r--r--mm/vmscan.c41
1 files changed, 41 insertions, 0 deletions
diff --git a/mm/vmscan.c b/mm/vmscan.c
index cb8ad3c6e48..bbd194630c5 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -932,6 +932,7 @@ static void shrink_active_list(unsigned long nr_pages, struct zone *zone,
long mapped_ratio;
long distress;
long swap_tendency;
+ long imbalance;
if (zone_is_near_oom(zone))
goto force_reclaim_mapped;
@@ -967,6 +968,46 @@ static void shrink_active_list(unsigned long nr_pages, struct zone *zone,
swap_tendency = mapped_ratio / 2 + distress + sc->swappiness;
/*
+ * If there's huge imbalance between active and inactive
+ * (think active 100 times larger than inactive) we should
+ * become more permissive, or the system will take too much
+ * cpu before it start swapping during memory pressure.
+ * Distress is about avoiding early-oom, this is about
+ * making swappiness graceful despite setting it to low
+ * values.
+ *
+ * Avoid div by zero with nr_inactive+1, and max resulting
+ * value is vm_total_pages.
+ */
+ imbalance = zone_page_state(zone, NR_ACTIVE);
+ imbalance /= zone_page_state(zone, NR_INACTIVE) + 1;
+
+ /*
+ * Reduce the effect of imbalance if swappiness is low,
+ * this means for a swappiness very low, the imbalance
+ * must be much higher than 100 for this logic to make
+ * the difference.
+ *
+ * Max temporary value is vm_total_pages*100.
+ */
+ imbalance *= (vm_swappiness + 1);
+ imbalance /= 100;
+
+ /*
+ * If not much of the ram is mapped, makes the imbalance
+ * less relevant, it's high priority we refill the inactive
+ * list with mapped pages only in presence of high ratio of
+ * mapped pages.
+ *
+ * Max temporary value is vm_total_pages*100.
+ */
+ imbalance *= mapped_ratio;
+ imbalance /= 100;
+
+ /* apply imbalance feedback to swap_tendency */
+ swap_tendency += imbalance;
+
+ /*
* Now use this metric to decide whether to start moving mapped
* memory onto the inactive list.
*/