memcg: remove mem_cgroup_cal_reclaim()

Now, get_scan_ratio() return correct value although memcg reclaim.  Then,
mem_cgroup_calc_reclaim() can be removed.

So, memcg reclaim get the same capability of anon/file reclaim balancing
as global reclaim now.
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@redhat.com>
Acked-by: Rik van Riel <riel@redhat.com>
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: Hugh Dickins <hugh@veritas.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/memcontrol.h

@@ -97,9 +97,6 @@ extern void mem_cgroup_note_reclaim_priority(struct mem_cgroup *mem,
 							int priority);
 extern void mem_cgroup_record_reclaim_priority(struct mem_cgroup *mem,
 							int priority);
-
-extern long mem_cgroup_calc_reclaim(struct mem_cgroup *mem, struct zone *zone,
-					int priority, enum lru_list lru);
 int mem_cgroup_inactive_anon_is_low(struct mem_cgroup *memcg,
 				    struct zone *zone);
 unsigned long mem_cgroup_zone_nr_pages(struct mem_cgroup *memcg,
@@ -244,13 +241,6 @@ static inline void mem_cgroup_record_reclaim_priority(struct mem_cgroup *mem,
 {
 }
 
-static inline long mem_cgroup_calc_reclaim(struct mem_cgroup *mem,
-					struct zone *zone, int priority,
-					enum lru_list lru)
-{
-	return 0;
-}
-
 static inline bool mem_cgroup_disabled(void)
 {
 	return true;

mm/memcontrol.c

@@ -414,27 +414,6 @@ void mem_cgroup_record_reclaim_priority(struct mem_cgroup *mem, int priority)
 	mem->prev_priority = priority;
 }
 
-/*
- * Calculate # of pages to be scanned in this priority/zone.
- * See also vmscan.c
- *
- * priority starts from "DEF_PRIORITY" and decremented in each loop.
- * (see include/linux/mmzone.h)
- */
-
-long mem_cgroup_calc_reclaim(struct mem_cgroup *mem, struct zone *zone,
-					int priority, enum lru_list lru)
-{
-	long nr_pages;
-	int nid = zone->zone_pgdat->node_id;
-	int zid = zone_idx(zone);
-	struct mem_cgroup_per_zone *mz = mem_cgroup_zoneinfo(mem, nid, zid);
-
-	nr_pages = MEM_CGROUP_ZSTAT(mz, lru);
-
-	return (nr_pages >> priority);
-}
-
 int mem_cgroup_inactive_anon_is_low(struct mem_cgroup *memcg, struct zone *zone)
 {
 	unsigned long active;

mm/vmscan.c

@@ -1466,7 +1466,6 @@ static void shrink_zone(int priority, struct zone *zone,
 	get_scan_ratio(zone, sc, percent);
 
 	for_each_evictable_lru(l) {
-		if (scan_global_lru(sc)) {
 		int file = is_file_lru(l);
 		int scan;
 
@@ -1475,21 +1474,15 @@ static void shrink_zone(int priority, struct zone *zone,
 			scan >>= priority;
 			scan = (scan * percent[file]) / 100;
 		}
+		if (scan_global_lru(sc)) {
 			zone->lru[l].nr_scan += scan;
 			nr[l] = zone->lru[l].nr_scan;
 			if (nr[l] >= swap_cluster_max)
 				zone->lru[l].nr_scan = 0;
 			else
 				nr[l] = 0;
-		} else {
-			/*
-			 * This reclaim occurs not because zone memory shortage
-			 * but because memory controller hits its limit.
-			 * Don't modify zone reclaim related data.
-			 */
-			nr[l] = mem_cgroup_calc_reclaim(sc->mem_cgroup, zone,
-								priority, l);
-		}
+		} else
+			nr[l] = scan;
 	}
 
 	while (nr[LRU_INACTIVE_ANON] || nr[LRU_ACTIVE_FILE] ||