From: Yejune Deng <yejune.deng@gmail.com>
To: cl@linux.com, penberg@kernel.org, rientjes@google.com,
iamjoonsoo.kim@lge.com, akpm@linux-foundation.org,
vbabka@suse.cz
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, yejune.deng@gmail.com
Subject: [PATCH] include/linux/slab.h: use for() and left shift to calculate
Date: Tue, 2 Mar 2021 11:39:08 +0800 [thread overview]
Message-ID: <20210302033908.51706-1-yejune.deng@gmail.com> (raw)
use for() and left shift to calculate the value that compared with size.
Signed-off-by: Yejune Deng <yejune.deng@gmail.com>
---
include/linux/slab.h | 32 ++++++++------------------------
1 file changed, 8 insertions(+), 24 deletions(-)
diff --git a/include/linux/slab.h b/include/linux/slab.h
index 7ae604076767..0411f57930fb 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -347,6 +347,8 @@ static __always_inline enum kmalloc_cache_type kmalloc_type(gfp_t flags)
*/
static __always_inline unsigned int kmalloc_index(size_t size)
{
+ int i;
+
if (!size)
return 0;
@@ -357,30 +359,12 @@ static __always_inline unsigned int kmalloc_index(size_t size)
return 1;
if (KMALLOC_MIN_SIZE <= 64 && size > 128 && size <= 192)
return 2;
- if (size <= 8) return 3;
- if (size <= 16) return 4;
- if (size <= 32) return 5;
- if (size <= 64) return 6;
- if (size <= 128) return 7;
- if (size <= 256) return 8;
- if (size <= 512) return 9;
- if (size <= 1024) return 10;
- if (size <= 2 * 1024) return 11;
- if (size <= 4 * 1024) return 12;
- if (size <= 8 * 1024) return 13;
- if (size <= 16 * 1024) return 14;
- if (size <= 32 * 1024) return 15;
- if (size <= 64 * 1024) return 16;
- if (size <= 128 * 1024) return 17;
- if (size <= 256 * 1024) return 18;
- if (size <= 512 * 1024) return 19;
- if (size <= 1024 * 1024) return 20;
- if (size <= 2 * 1024 * 1024) return 21;
- if (size <= 4 * 1024 * 1024) return 22;
- if (size <= 8 * 1024 * 1024) return 23;
- if (size <= 16 * 1024 * 1024) return 24;
- if (size <= 32 * 1024 * 1024) return 25;
- if (size <= 64 * 1024 * 1024) return 26;
+
+ /* The maximum of size is 2^26 = 64 * 1024 * 1024 */
+ for (i = 3; i <= 26; i++) {
+ if (size <= (1 << i))
+ return i;
+ }
BUG();
/* Will never be reached. Needed because the compiler may complain */
--
2.29.0
next reply other threads:[~2021-03-02 8:12 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-02 3:39 Yejune Deng [this message]
2021-03-02 3:52 ` [PATCH] include/linux/slab.h: use for() and left shift to calculate Matthew Wilcox
2021-03-02 9:09 ` Christoph Lameter
2021-03-02 13:55 ` Yejune Deng
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