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| author |   Waiman Long <Waiman.Long@hp.com> | 2013-07-23 17:38:41 -0400 |
|---|---|---|
| committer |   Eric Paris <eparis@redhat.com> | 2013-07-25 13:02:31 -0400 |
| commit | a767f680e34bf14a36fefbbb6d85783eef99fd57 (patch) | |
| tree | 283889d4951dcb42a4de713e144f2d556552c27c /security/selinux/ss/ebitmap.h | |
| parent | SELinux: Reduce overhead of mls_level_isvalid() function call (diff) | |
| download | linux-dev-a767f680e34bf14a36fefbbb6d85783eef99fd57.tar.xz linux-dev-a767f680e34bf14a36fefbbb6d85783eef99fd57.zip | |
SELinux: Increase ebitmap_node size for 64-bit configuration
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>
Acked-by: Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: Paul Moore <pmoore@redhat.com>
Signed-off-by: Eric Paris <eparis@redhat.com>
Diffstat (limited to 'security/selinux/ss/ebitmap.h')
| -rw-r--r-- | 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 e7eb3a9c5ab7..712c8a7b8e8b 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) |