[RFC 8/8] Optimize mempolicies for a single zone

[Christoph Lameter <clameter@sgi.com>]

Use SINGLE_ZONE to remove the highest zone determination

Siged-off-by: Christoph Lameter <clameter@sgi.com>

Index: linux-2.6.17-mm6/mm/mempolicy.c
===================================================================
--- linux-2.6.17-mm6.orig/mm/mempolicy.c	2006-07-07 16:50:18.790221361 -0700
+++ linux-2.6.17-mm6/mm/mempolicy.c	2006-07-07 16:53:46.057679926 -0700
@@ -103,9 +103,11 @@ static struct kmem_cache *sn_cache;
 
 #define PDprintk(fmt...)
 
+#ifndef SINGLE_ZONE
 /* Highest zone. An specific allocation for a zone below that is not
    policied. */
 int policy_zone = 0;
+#endif
 
 struct mempolicy default_policy = {
 	.refcnt = ATOMIC_INIT(1), /* never free it */
Index: linux-2.6.17-mm6/include/linux/mempolicy.h
===================================================================
--- linux-2.6.17-mm6.orig/include/linux/mempolicy.h	2006-07-03 13:47:21.727467854 -0700
+++ linux-2.6.17-mm6/include/linux/mempolicy.h	2006-07-07 16:53:46.057679926 -0700
@@ -162,12 +162,18 @@ extern struct zonelist *huge_zonelist(st
 		unsigned long addr);
 extern unsigned slab_node(struct mempolicy *policy);
 
+#ifndef SINGLE_ZONE
+#define policy_zone ZONE_NORMAL
+#else
 extern int policy_zone;
+#endif
 
 static inline void check_highest_zone(int k)
 {
+#ifndef SINGLE_ZONE
 	if (k > policy_zone)
 		policy_zone = k;
+#endif
 }
 
 int do_migrate_pages(struct mm_struct *mm,