[PATCH] linearly index zone->node_zonelists[]

I wonder why we need this bitmask indexing into zone->node_zonelists[]?

We always start with the highest zone and then include all lower zones
if we build zonelists.

Are there really cases where we need allocation from ZONE_DMA or
ZONE_HIGHMEM but not ZONE_NORMAL? It seems that the current implementation
of highest_zone() makes that already impossible.

If we go linear on the index then gfp_zone() == highest_zone() and a lot
of definitions fall by the wayside.

We can now revert back to the use of gfp_zone() in mempolicy.c ;-)

Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 11 insertions, 16 deletions

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 9c44b9a39d30..208a6b03aa78 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1444,14 +1444,14 @@ static int __meminit find_next_best_node(int node, nodemask_t *used_node_mask)
 
 static void __meminit build_zonelists(pg_data_t *pgdat)
 {
-        int i, j, node, local_node;
+        int j, node, local_node;
+        enum zone_type i;
         int prev_node, load;
         struct zonelist *zonelist;
         nodemask_t used_mask;
-        enum zone_type k;
 
         /* initialize zonelists */
-        for (i = 0; i < GFP_ZONETYPES; i++) {
+        for (i = 0; i < MAX_NR_ZONES; i++) {
                 zonelist = pgdat->node_zonelists + i;
                 zonelist->zones[0] = NULL;
         }
@@ -1481,13 +1481,11 @@ static void __meminit build_zonelists(pg_data_t *pgdat)
                         node_load[node] += load;
                 prev_node = node;
                 load--;
-                for (i = 0; i < GFP_ZONETYPES; i++) {
+                for (i = 0; i < MAX_NR_ZONES; i++) {
                         zonelist = pgdat->node_zonelists + i;
                         for (j = 0; zonelist->zones[j] != NULL; j++);
 
-                        k = highest_zone(i);
-
-                        j = build_zonelists_node(NODE_DATA(node), zonelist, j, k);
+                        j = build_zonelists_node(NODE_DATA(node), zonelist, j, i);
                         zonelist->zones[j] = NULL;
                 }
         }
@@ -1497,19 +1495,16 @@ static void __meminit build_zonelists(pg_data_t *pgdat)
 
 static void __meminit build_zonelists(pg_data_t *pgdat)
 {
-        int i, node, local_node;
-        enum zone_type k;
-        enum zone_type j;
+        int node, local_node;
+        enum zone_type i,j;
 
         local_node = pgdat->node_id;
-        for (i = 0; i < GFP_ZONETYPES; i++) {
+        for (i = 0; i < MAX_NR_ZONES; i++) {
                 struct zonelist *zonelist;
 
                 zonelist = pgdat->node_zonelists + i;
 
-                j = 0;
-                k = highest_zone(i);
-                j = build_zonelists_node(pgdat, zonelist, j, k);
+                j = build_zonelists_node(pgdat, zonelist, 0, i);
                 /*
                  * Now we build the zonelist so that it contains the zones
                  * of all the other nodes.
@@ -1521,12 +1516,12 @@ static void __meminit build_zonelists(pg_data_t *pgdat)
                 for (node = local_node + 1; node < MAX_NUMNODES; node++) {
                         if (!node_online(node))
                                 continue;
-                        j = build_zonelists_node(NODE_DATA(node), zonelist, j, k);
+                        j = build_zonelists_node(NODE_DATA(node), zonelist, j, i);
                 }
                 for (node = 0; node < local_node; node++) {
                         if (!node_online(node))
                                 continue;
-                        j = build_zonelists_node(NODE_DATA(node), zonelist, j, k);
+                        j = build_zonelists_node(NODE_DATA(node), zonelist, j, i);
                 }
 
                 zonelist->zones[j] = NULL;