mm: use two zonelist that are filtered by GFP mask

Currently a node has two sets of zonelists, one for each zone type in the
system and a second set for GFP_THISNODE allocations.  Based on the zones
allowed by a gfp mask, one of these zonelists is selected.  All of these
zonelists consume memory and occupy cache lines.

This patch replaces the multiple zonelists per-node with two zonelists.  The
first contains all populated zones in the system, ordered by distance, for
fallback allocations when the target/preferred node has no free pages.  The
second contains all populated zones in the node suitable for GFP_THISNODE
allocations.

An iterator macro is introduced called for_each_zone_zonelist() that interates
through each zone allowed by the GFP flags in the selected zonelist.

Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Acked-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Christoph Lameter <clameter@sgi.com>
Cc: Hugh Dickins <hugh@veritas.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 9 insertions, 12 deletions

diff --git a/mm/vmscan.c b/mm/vmscan.c
index ef8551e0d2d0..0515b8f44894 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1249,15 +1249,13 @@ static unsigned long shrink_zone(int priority, struct zone *zone,
 static unsigned long shrink_zones(int priority, struct zonelist *zonelist,
                                         struct scan_control *sc)
 {
+        enum zone_type high_zoneidx = gfp_zone(sc->gfp_mask);
         unsigned long nr_reclaimed = 0;
-        struct zone **zones = zonelist->zones;
-        int i;
-
+        struct zone **z;
+        struct zone *zone;
 
         sc->all_unreclaimable = 1;
-        for (i = 0; zones[i] != NULL; i++) {
-                struct zone *zone = zones[i];
-
+        for_each_zone_zonelist(zone, z, zonelist, high_zoneidx) {
                 if (!populated_zone(zone))
                         continue;
                 /*
@@ -1311,8 +1309,9 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist,
         unsigned long nr_reclaimed = 0;
         struct reclaim_state *reclaim_state = current->reclaim_state;
         unsigned long lru_pages = 0;
-        struct zone **zones = zonelist->zones;
-        int i;
+        struct zone **z;
+        struct zone *zone;
+        enum zone_type high_zoneidx = gfp_zone(gfp_mask);
 
         if (scan_global_lru(sc))
                 count_vm_event(ALLOCSTALL);
@@ -1320,8 +1319,7 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist,
          * mem_cgroup will not do shrink_slab.
          */
         if (scan_global_lru(sc)) {
-                for (i = 0; zones[i] != NULL; i++) {
-                        struct zone *zone = zones[i];
+                for_each_zone_zonelist(zone, z, zonelist, high_zoneidx) {
 
                         if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL))
                                 continue;
@@ -1385,8 +1383,7 @@ out:
                 priority = 0;
 
         if (scan_global_lru(sc)) {
-                for (i = 0; zones[i] != NULL; i++) {
-                        struct zone *zone = zones[i];
+                for_each_zone_zonelist(zone, z, zonelist, high_zoneidx) {
 
                         if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL))
                                 continue;