From 73de519c41972b48fd3c4c5c35075bd48056495d Mon Sep 17 00:00:00 2001
From: Nick Piggin <nickpiggin@yahoo.com.au>
Date: Sun, 1 May 2005 08:58:36 -0700
Subject: [PATCH] --- yaml --- r: 625 b: refs/heads/master c:
 8e30f272a93ec9c1d5c305c5040dfaebc880499d h: refs/heads/master i:   623:
 4506dffb98eb06d74e5975313a35c080f732880b v: v3

---
 [refs]                |  2 +-
 trunk/mm/page_alloc.c | 12 ++++++++++++
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/[refs] b/[refs]
index 30c275a81fdf..9bd499099ae5 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 81b4082dc7666e2bc5ec229d8e837f3bafb96883
+refs/heads/master: 8e30f272a93ec9c1d5c305c5040dfaebc880499d
diff --git a/trunk/mm/page_alloc.c b/trunk/mm/page_alloc.c
index c73dbbc1cd8f..08e8627361a0 100644
--- a/trunk/mm/page_alloc.c
+++ b/trunk/mm/page_alloc.c
@@ -1671,6 +1671,18 @@ static void __init free_area_init_core(struct pglist_data *pgdat,
 		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;
+
 		for (cpu = 0; cpu < NR_CPUS; cpu++) {
 			struct per_cpu_pages *pcp;