diff options
author | Eric Dumazet <dada1@resalehost.networksolutions.com> | 2006-03-25 12:08:00 +0100 |
---|---|---|
committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-03-25 17:22:58 +0100 |
commit | 231bed205879236357171e50bd8965e70797ecdc (patch) | |
tree | fe3bb52388510eca3fc19548abd26f4009b94db1 /include | |
parent | [PATCH] Ext2 flags shouldn't report "nogrpid" (diff) | |
download | linux-231bed205879236357171e50bd8965e70797ecdc.tar.xz linux-231bed205879236357171e50bd8965e70797ecdc.zip |
[PATCH] No need to protect current->group_info in sys_getgroups(), in_group_p() and in_egroup_p()
While doing some benchmarks of an Apache/PHP SMP server, I noticed high
oprofile numbers in in_group_p() and _atomic_dec_and_lock().
rank percent
1 4.8911 % __link_path_walk
2 4.8503 % __d_lookup
*3 4.2911 % _atomic_dec_and_lock
4 3.9307 % __copy_to_user_ll
5 4.9004 % sysenter_past_esp
*6 3.3248 % in_group_p
It appears that in_group_p() does an uncessary
get_group_info(current->group_info); /* atomic_inc() */
... /* access current->group_info */
put_group_info(current->group_info); /* _atomic_dec_and_lock */
It is not necessary to do this, because the current task holds a reference
on its own group_info, and this reference cannot change during the lookup.
This patch deletes the get_group_info()/put_group_info() pair from
sys_getgroups(), in_group_p() and in_egroup_p() functions.
Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Cc: Tim Hockin <thockin@hockin.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'include')
0 files changed, 0 insertions, 0 deletions