From ff3881079f8200d7a5cbe4d908777fc368e26f82 Mon Sep 17 00:00:00 2001
From: "Seth, Rohit" <rohit.seth@intel.com>
Date: Sat, 29 Oct 2005 18:15:47 -0700
Subject: [PATCH] --- yaml --- r: 11319 b: refs/heads/master c:
 ba56e91c940146e99ac694c4c7cd7f2b4aaa565d h: refs/heads/master i:   11317:
 c35e044e332caa80f956a2bfda59bf65d473352b   11315:
 6343f85af2ca19862ed10c4fbf31ab7bb5e4a29f   11311:
 ff3e0f9bef0f3a6c6f7c0c1282e91c78b599aeff v: v3

---
 [refs]                |  2 +-
 trunk/mm/page_alloc.c | 24 ++++++++++++------------
 2 files changed, 13 insertions(+), 13 deletions(-)

diff --git a/[refs] b/[refs]
index 5a56534a94ee..64a9d9f43e96 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: fcdae29aa7a5c79f245110f6680afdc1858d3626
+refs/heads/master: ba56e91c940146e99ac694c4c7cd7f2b4aaa565d
diff --git a/trunk/mm/page_alloc.c b/trunk/mm/page_alloc.c
index 94c864eac9c4..f799217dc2f3 100644
--- a/trunk/mm/page_alloc.c
+++ b/trunk/mm/page_alloc.c
@@ -1721,29 +1721,29 @@ static int __devinit zone_batchsize(struct zone *zone)
 
 	/*
 	 * The per-cpu-pages pools are set to around 1000th of the
-	 * size of the zone.  But no more than 1/4 of a meg - there's
-	 * no point in going beyond the size of L2 cache.
+	 * size of the zone.  But no more than 1/2 of a meg.
 	 *
 	 * OK, so we don't know how big the cache is.  So guess.
 	 */
 	batch = zone->present_pages / 1024;
-	if (batch * PAGE_SIZE > 256 * 1024)
-		batch = (256 * 1024) / PAGE_SIZE;
+	if (batch * PAGE_SIZE > 512 * 1024)
+		batch = (512 * 1024) / PAGE_SIZE;
 	batch /= 4;		/* We effectively *= 4 below */
 	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.
+	 * We will be trying to allcoate bigger chunks of contiguous
+	 * memory of the order of fls(batch).  This should result in
+	 * better cache coloring.
 	 *
-	 * 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.
+	 * A sanity check also to ensure that batch is still in limits.
 	 */
-	batch = (1 << fls(batch + batch/2)) - 1;
+	batch = (1 << fls(batch + batch/2));
+
+	if (fls(batch) >= (PAGE_SHIFT + MAX_ORDER - 2))
+		batch = PAGE_SHIFT + ((MAX_ORDER - 1 - PAGE_SHIFT)/2);
+
 	return batch;
 }