From: Wei Yang <weiyang@linux.vnet.ibm.com>
Date: Fri, 6 Nov 2015 02:45:51 +0000 (-0800)
Subject: mm/slub: calculate start order with reserved in consideration
X-Git-Tag: firefly_0821_release~176^2~776^2~117
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=9f835703ea67633617ca82bc150f6ee70831b40a;p=firefly-linux-kernel-4.4.55.git

mm/slub: calculate start order with reserved in consideration

In slub_order(), the order starts from max(min_order,
get_order(min_objects * size)).  When (min_objects * size) has different
order from (min_objects * size + reserved), it will skip this order via a
check in the loop.

This patch optimizes this a little by calculating the start order with
`reserved' in consideration and removing the check in loop.

Signed-off-by: Wei Yang <weiyang@linux.vnet.ibm.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

diff --git a/mm/slub.c b/mm/slub.c
index e309ed140fd1..e1bb147827ef 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -2912,19 +2912,15 @@ static inline int slab_order(int size, int min_objects,
 	if (order_objects(min_order, size, reserved) > MAX_OBJS_PER_PAGE)
 		return get_order(size * MAX_OBJS_PER_PAGE) - 1;
 
-	for (order = max(min_order, get_order(min_objects * size));
+	for (order = max(min_order, get_order(min_objects * size + reserved));
 			order <= max_order; order++) {
 
 		unsigned long slab_size = PAGE_SIZE << order;
 
-		if (slab_size < min_objects * size + reserved)
-			continue;
-
 		rem = (slab_size - reserved) % size;
 
 		if (rem <= slab_size / fract_leftover)
 			break;
-
 	}
 
 	return order;