lkml.org 
[lkml]   [2013]   [Jun]   [5]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH v2 2/2] SELinux: Increase ebitmap_node size for 64-bit configuration
Date
Currently, the ebitmap_node structure has a fixed size of 32 bytes. On
a 32-bit system, the overhead is 8 bytes, leaving 24 bytes for being
used as bitmaps. The overhead ratio is 1/4.

On a 64-bit system, the overhead is 16 bytes. Therefore, only 16 bytes
are left for bitmap purpose and the overhead ratio is 1/2. With a
3.8.2 kernel, a boot-up operation will cause the ebitmap_get_bit()
function to be called about 9 million times. The average number of
ebitmap_node traversal is about 3.7.

This patch increases the size of the ebitmap_node structure to 64
bytes for 64-bit system to keep the overhead ratio at 1/4. This may
also improve performance a little bit by making node to node traversal
less frequent (< 2) as more bits are available in each node.

Signed-off-by: Waiman Long <Waiman.Long@hp.com>
---
security/selinux/ss/ebitmap.h | 8 +++++++-
1 files changed, 7 insertions(+), 1 deletions(-)

diff --git a/security/selinux/ss/ebitmap.h b/security/selinux/ss/ebitmap.h
index e7eb3a9..712c8a7 100644
--- a/security/selinux/ss/ebitmap.h
+++ b/security/selinux/ss/ebitmap.h
@@ -16,7 +16,13 @@

#include <net/netlabel.h>

-#define EBITMAP_UNIT_NUMS ((32 - sizeof(void *) - sizeof(u32)) \
+#ifdef CONFIG_64BIT
+#define EBITMAP_NODE_SIZE 64
+#else
+#define EBITMAP_NODE_SIZE 32
+#endif
+
+#define EBITMAP_UNIT_NUMS ((EBITMAP_NODE_SIZE-sizeof(void *)-sizeof(u32))\
/ sizeof(unsigned long))
#define EBITMAP_UNIT_SIZE BITS_PER_LONG
#define EBITMAP_SIZE (EBITMAP_UNIT_NUMS * EBITMAP_UNIT_SIZE)
--
1.7.1


\
 
 \ /
  Last update: 2013-06-06 00:41    [W:0.053 / U:1.100 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site