mm: vmscan: limit the range of LRU type balancing

[linux-2.6-microblaze.git] / mm / vmscan.c

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 14ffe9c..3792dd1 100644 (file)
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2237,12 +2237,11 @@ static void get_scan_count(struct lruvec *lruvec, struct scan_control *sc,
                           unsigned long *nr)
 {
        struct mem_cgroup *memcg = lruvec_memcg(lruvec);
+       unsigned long anon_cost, file_cost, total_cost;
        int swappiness = mem_cgroup_swappiness(memcg);
        u64 fraction[2];
        u64 denominator = 0;    /* gcc */
-       unsigned long anon_prio, file_prio;
        enum scan_balance scan_balance;
-       unsigned long totalcost;
        unsigned long ap, fp;
        enum lru_list lru;
 
@@ -2301,17 +2300,22 @@ static void get_scan_count(struct lruvec *lruvec, struct scan_control *sc,
         * the relative IO cost of bringing back a swapped out
         * anonymous page vs reloading a filesystem page (swappiness).
         *
+        * Although we limit that influence to ensure no list gets
+        * left behind completely: at least a third of the pressure is
+        * applied, before swappiness.
+        *
         * With swappiness at 100, anon and file have equal IO cost.
         */
-       anon_prio = swappiness;
-       file_prio = 200 - anon_prio;
+       total_cost = sc->anon_cost + sc->file_cost;
+       anon_cost = total_cost + sc->anon_cost;
+       file_cost = total_cost + sc->file_cost;
+       total_cost = anon_cost + file_cost;
 
-       totalcost = sc->anon_cost + sc->file_cost;
-       ap = anon_prio * (totalcost + 1);
-       ap /= sc->anon_cost + 1;
+       ap = swappiness * (total_cost + 1);
+       ap /= anon_cost + 1;
 
-       fp = file_prio * (totalcost + 1);
-       fp /= sc->file_cost + 1;
+       fp = (200 - swappiness) * (total_cost + 1);
+       fp /= file_cost + 1;
 
        fraction[0] = ap;
        fraction[1] = fp;