Index: linux-2.6/mm/page_alloc.c
===================================================================
--- linux-2.6.orig/mm/page_alloc.c	2005-04-09 23:13:53.000000000 +1000
+++ linux-2.6/mm/page_alloc.c	2005-04-09 23:59:36.000000000 +1000
@@ -1623,6 +1623,18 @@ void __init build_percpu_pagelists(void)
 			if (batch < 1)
 				batch = 1;
 
+			/*
+			 * Clamp the batch to a 2^n - 1 value. Having a power
+			 * of 2 value was found to be more likely to have
+			 * suboptimal cache aliasing properties in some cases.
+			 *
+			 * For example if 2 tasks are alternately allocating
+			 * batches of pages, one task can end up with a lot
+			 * of pages of one half of the possible page colors
+			 * and the other with pages of the other colors.
+			 */
+			batch = (1 << fls(batch + batch/2)) - 1;
+
 			init_percpu_pageset(&zone->pageset, batch);
 			for (cpu = 0; cpu < NR_CPUS; cpu++) {
 				struct zone_pagesets *zp;