vmscan: Use an indexed array for LRU variables

Currently we are defining explicit variables for the inactive and active
list.  An indexed array can be more generic and avoid repeating similar
code in several places in the reclaim code.

We are saving a few bytes in terms of code size:

Before:

   text    data     bss     dec     hex filename
4097753  573120 4092484 8763357  85b7dd vmlinux

After:

   text    data     bss     dec     hex filename
4097729  573120 4092484 8763333  85b7c5 vmlinux

Having an easy way to add new lru lists may ease future work on the
reclaim code.

Signed-off-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com>
Signed-off-by: Christoph Lameter <cl@linux-foundation.org>
Signed-off-by: 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>

1 files changed, 57 insertions, 63 deletions

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 1fd4912..46fdaa5 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -819,10 +819,10 @@ static unsigned long isolate_pages_global(unsigned long nr,
 					int active)
 {
 	if (active)
-		return isolate_lru_pages(nr, &z->active_list, dst,
+		return isolate_lru_pages(nr, &z->lru[LRU_ACTIVE].list, dst,
 						scanned, order, mode);
 	else
-		return isolate_lru_pages(nr, &z->inactive_list, dst,
+		return isolate_lru_pages(nr, &z->lru[LRU_INACTIVE].list, dst,
 						scanned, order, mode);
 }
 
@@ -973,10 +973,7 @@ static unsigned long shrink_inactive_list(unsigned long max_scan,
 			VM_BUG_ON(PageLRU(page));
 			SetPageLRU(page);
 			list_del(&page->lru);
-			if (PageActive(page))
-				add_page_to_active_list(zone, page);
-			else
-				add_page_to_inactive_list(zone, page);
+			add_page_to_lru_list(zone, page, page_lru(page));
 			if (!pagevec_add(&pvec, page)) {
 				spin_unlock_irq(&zone->lru_lock);
 				__pagevec_release(&pvec);
@@ -1144,8 +1141,8 @@ static void shrink_active_list(unsigned long nr_pages, struct zone *zone,
 	int pgdeactivate = 0;
 	unsigned long pgscanned;
 	LIST_HEAD(l_hold);	/* The pages which were snipped off */
-	LIST_HEAD(l_inactive);	/* Pages to go onto the inactive_list */
-	LIST_HEAD(l_active);	/* Pages to go onto the active_list */
+	LIST_HEAD(l_active);
+	LIST_HEAD(l_inactive);
 	struct page *page;
 	struct pagevec pvec;
 	int reclaim_mapped = 0;
@@ -1194,7 +1191,7 @@ static void shrink_active_list(unsigned long nr_pages, struct zone *zone,
 		VM_BUG_ON(!PageActive(page));
 		ClearPageActive(page);
 
-		list_move(&page->lru, &zone->inactive_list);
+		list_move(&page->lru, &zone->lru[LRU_INACTIVE].list);
 		mem_cgroup_move_lists(page, false);
 		pgmoved++;
 		if (!pagevec_add(&pvec, page)) {
@@ -1224,7 +1221,7 @@ static void shrink_active_list(unsigned long nr_pages, struct zone *zone,
 		SetPageLRU(page);
 		VM_BUG_ON(!PageActive(page));
 
-		list_move(&page->lru, &zone->active_list);
+		list_move(&page->lru, &zone->lru[LRU_ACTIVE].list);
 		mem_cgroup_move_lists(page, true);
 		pgmoved++;
 		if (!pagevec_add(&pvec, page)) {
@@ -1244,65 +1241,64 @@ static void shrink_active_list(unsigned long nr_pages, struct zone *zone,
 	pagevec_release(&pvec);
 }
 
+static unsigned long shrink_list(enum lru_list l, unsigned long nr_to_scan,
+	struct zone *zone, struct scan_control *sc, int priority)
+{
+	if (l == LRU_ACTIVE) {
+		shrink_active_list(nr_to_scan, zone, sc, priority);
+		return 0;
+	}
+	return shrink_inactive_list(nr_to_scan, zone, sc);
+}
+
 /*
  * This is a basic per-zone page freer.  Used by both kswapd and direct reclaim.
  */
 static unsigned long shrink_zone(int priority, struct zone *zone,
 				struct scan_control *sc)
 {
-	unsigned long nr_active;
-	unsigned long nr_inactive;
+	unsigned long nr[NR_LRU_LISTS];
 	unsigned long nr_to_scan;
 	unsigned long nr_reclaimed = 0;
+	enum lru_list l;
 
 	if (scan_global_lru(sc)) {
 		/*
 		 * Add one to nr_to_scan just to make sure that the kernel
 		 * will slowly sift through the active list.
 		 */
-		zone->nr_scan_active +=
-			(zone_page_state(zone, NR_ACTIVE) >> priority) + 1;
-		nr_active = zone->nr_scan_active;
-		zone->nr_scan_inactive +=
-			(zone_page_state(zone, NR_INACTIVE) >> priority) + 1;
-		nr_inactive = zone->nr_scan_inactive;
-		if (nr_inactive >= sc->swap_cluster_max)
-			zone->nr_scan_inactive = 0;
-		else
-			nr_inactive = 0;
-
-		if (nr_active >= sc->swap_cluster_max)
-			zone->nr_scan_active = 0;
-		else
-			nr_active = 0;
+		for_each_lru(l) {
+			zone->lru[l].nr_scan += (zone_page_state(zone,
+					NR_LRU_BASE + l)  >> priority) + 1;
+			nr[l] = zone->lru[l].nr_scan;
+			if (nr[l] >= sc->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.
 		 * Then, don't modify zone reclaim related data.
 		 */
-		nr_active = mem_cgroup_calc_reclaim_active(sc->mem_cgroup,
-					zone, priority);
+		nr[LRU_ACTIVE] = mem_cgroup_calc_reclaim(sc->mem_cgroup,
+					zone, priority, LRU_ACTIVE);
 
-		nr_inactive = mem_cgroup_calc_reclaim_inactive(sc->mem_cgroup,
-					zone, priority);
+		nr[LRU_INACTIVE] = mem_cgroup_calc_reclaim(sc->mem_cgroup,
+					zone, priority, LRU_INACTIVE);
 	}
 
-
-	while (nr_active || nr_inactive) {
-		if (nr_active) {
-			nr_to_scan = min(nr_active,
+	while (nr[LRU_ACTIVE] || nr[LRU_INACTIVE]) {
+		for_each_lru(l) {
+			if (nr[l]) {
+				nr_to_scan = min(nr[l],
 					(unsigned long)sc->swap_cluster_max);
-			nr_active -= nr_to_scan;
-			shrink_active_list(nr_to_scan, zone, sc, priority);
-		}
+				nr[l] -= nr_to_scan;
 
-		if (nr_inactive) {
-			nr_to_scan = min(nr_inactive,
-					(unsigned long)sc->swap_cluster_max);
-			nr_inactive -= nr_to_scan;
-			nr_reclaimed += shrink_inactive_list(nr_to_scan, zone,
-								sc);
+				nr_reclaimed += shrink_list(l, nr_to_scan,
+							zone, sc, priority);
+			}
 		}
 	}
 
@@ -1819,6 +1815,7 @@ static unsigned long shrink_all_zones(unsigned long nr_pages, int prio,
 {
 	struct zone *zone;
 	unsigned long nr_to_scan, ret = 0;
+	enum lru_list l;
 
 	for_each_zone(zone) {
 
@@ -1828,28 +1825,25 @@ static unsigned long shrink_all_zones(unsigned long nr_pages, int prio,
 		if (zone_is_all_unreclaimable(zone) && prio != DEF_PRIORITY)
 			continue;
 
-		/* For pass = 0 we don't shrink the active list */
-		if (pass > 0) {
-			zone->nr_scan_active +=
-				(zone_page_state(zone, NR_ACTIVE) >> prio) + 1;
-			if (zone->nr_scan_active >= nr_pages || pass > 3) {
-				zone->nr_scan_active = 0;
+		for_each_lru(l) {
+			/* For pass = 0 we don't shrink the active list */
+			if (pass == 0 && l == LRU_ACTIVE)
+				continue;
+
+			zone->lru[l].nr_scan +=
+				(zone_page_state(zone, NR_LRU_BASE + l)
+								>> prio) + 1;
+			if (zone->lru[l].nr_scan >= nr_pages || pass > 3) {
+				zone->lru[l].nr_scan = 0;
 				nr_to_scan = min(nr_pages,
-					zone_page_state(zone, NR_ACTIVE));
-				shrink_active_list(nr_to_scan, zone, sc, prio);
+					zone_page_state(zone,
+							NR_LRU_BASE + l));
+				ret += shrink_list(l, nr_to_scan, zone,
+								sc, prio);
+				if (ret >= nr_pages)
+					return ret;
 			}
 		}
-
-		zone->nr_scan_inactive +=
-			(zone_page_state(zone, NR_INACTIVE) >> prio) + 1;
-		if (zone->nr_scan_inactive >= nr_pages || pass > 3) {
-			zone->nr_scan_inactive = 0;
-			nr_to_scan = min(nr_pages,
-				zone_page_state(zone, NR_INACTIVE));
-			ret += shrink_inactive_list(nr_to_scan, zone, sc);
-			if (ret >= nr_pages)
-				return ret;
-		}
 	}
 
 	return ret;