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From: Alexey Dobriyan <adobriyan@gmail.com>
To: akpm@linux-foundation.org
Cc: linux-mm@kvack.org, cl@linux.com, penberg@kernel.org,
	rientjes@google.com, iamjoonsoo.kim@lge.com,
	Alexey Dobriyan <adobriyan@gmail.com>
Subject: [PATCH 06/23] slab: make size_index[] array u8
Date: Fri, 24 Nov 2017 01:16:11 +0300	[thread overview]
Message-ID: <20171123221628.8313-6-adobriyan@gmail.com> (raw)
In-Reply-To: <20171123221628.8313-1-adobriyan@gmail.com>

All those small numbers are reverse indexes into kmalloc caches array
and can't be negative.

On x86_64 "unsigned int = fls()" can drop CDQE:

	add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-2 (-2)
	Function                                     old     new   delta
	kmalloc_slab                                 101      99      -2

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
---
 mm/slab_common.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/slab_common.c b/mm/slab_common.c
index 1d46602c881e..4405af3ee8eb 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -927,7 +927,7 @@ EXPORT_SYMBOL(kmalloc_dma_caches);
  * of two cache sizes there. The size of larger slabs can be determined using
  * fls.
  */
-static s8 size_index[24] = {
+static u8 size_index[24] = {
 	3,	/* 8 */
 	4,	/* 16 */
 	5,	/* 24 */
@@ -965,7 +965,7 @@ static inline int size_index_elem(size_t bytes)
  */
 struct kmem_cache *kmalloc_slab(size_t size, gfp_t flags)
 {
-	int index;
+	unsigned int index;
 
 	if (unlikely(size > KMALLOC_MAX_SIZE)) {
 		WARN_ON_ONCE(!(flags & __GFP_NOWARN));
-- 
2.13.6

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  parent reply	other threads:[~2017-11-23 22:17 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-11-23 22:16 [PATCH 01/23] slab: make kmalloc_index() return "unsigned int" Alexey Dobriyan
2017-11-23 22:16 ` [PATCH 02/23] slab: make kmalloc_size() " Alexey Dobriyan
2017-11-23 22:16 ` [PATCH 03/23] slab: create_kmalloc_cache() works with 32-bit sizes Alexey Dobriyan
2017-11-24  1:06   ` Matthew Wilcox
2017-11-27 10:21     ` Alexey Dobriyan
2017-11-27 13:56       ` Matthew Wilcox
2017-11-23 22:16 ` [PATCH 04/23] slab: create_boot_cache() only " Alexey Dobriyan
2017-11-23 22:16 ` [PATCH 05/23] slab: kmem_cache_create() " Alexey Dobriyan
2017-11-23 22:16 ` Alexey Dobriyan [this message]
2017-11-23 22:16 ` [PATCH 07/23] slab: make size_index_elem() unsigned int Alexey Dobriyan
2017-11-23 22:16 ` [PATCH 08/23] slub: make ->remote_node_defrag_ratio " Alexey Dobriyan
2017-11-23 22:16 ` [PATCH 09/23] slub: make ->max_attr_size " Alexey Dobriyan
2017-11-23 22:16 ` [PATCH 10/23] slub: make ->red_left_pad " Alexey Dobriyan
2017-11-23 22:16 ` [PATCH 11/23] slub: make ->reserved " Alexey Dobriyan
2017-11-23 22:16 ` [PATCH 12/23] slub: make ->align " Alexey Dobriyan
2017-11-23 22:16 ` [PATCH 13/23] slub: make ->inuse " Alexey Dobriyan
2017-11-23 22:16 ` [PATCH 14/23] slub: make ->cpu_partial " Alexey Dobriyan
2017-11-23 22:16 ` [PATCH 15/23] slub: make ->offset " Alexey Dobriyan
2017-11-23 22:16 ` [PATCH 16/23] slub: make ->object_size " Alexey Dobriyan
2017-11-23 22:16 ` [PATCH 17/23] slub: make ->size " Alexey Dobriyan
2017-11-23 22:16 ` [PATCH 18/23] slab: make kmem_cache_flags accept 32-bit object size Alexey Dobriyan
2017-11-23 22:16 ` [PATCH 19/23] kasan: make kasan_cache_create() work with 32-bit slab caches Alexey Dobriyan
2017-11-24 22:29   ` kbuild test robot
2017-11-23 22:16 ` [PATCH 20/23] slub: make slab_index() return unsigned int Alexey Dobriyan
2017-11-23 22:16 ` [PATCH 21/23] slub: make struct kmem_cache_order_objects::x " Alexey Dobriyan
2017-11-24 17:31   ` Christopher Lameter
2017-11-27 10:17     ` Alexey Dobriyan
2017-11-23 22:16 ` [PATCH 22/23] slub: make size_from_object() return " Alexey Dobriyan
2017-11-23 22:16 ` [PATCH 23/23] slab: use 32-bit arithmetic in freelist_randomize() Alexey Dobriyan
2017-11-28  0:36 ` [PATCH 01/23] slab: make kmalloc_index() return "unsigned int" Andrew Morton
2017-11-28 18:46   ` Christopher Lameter

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