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Eric Dumazet 231bed2058 [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>
2006-03-25 08:22:58 -08:00
..
irq [PATCH] IRQ: prevent enabling of previously disabled interrupt 2006-03-25 08:22:55 -08:00
power [PATCH] sem2mutex: kernel/ 2006-03-23 07:38:10 -08:00
.gitignore gitignore: ignore more generated files 2006-01-03 11:35:26 +01:00
acct.c [PATCH] move capable() to capability.h 2006-01-11 18:42:13 -08:00
audit.c [PATCH] EDAC: atomic scrub operations 2006-01-18 19:20:30 -08:00
auditsc.c Merge ../powerpc-merge 2006-02-24 14:05:47 +11:00
capability.c [PATCH] refactor capable() to one implementation, add __capable() helper 2006-03-25 08:22:56 -08:00
compat.c [PATCH] remove bogus asm/bug.h includes. 2006-02-07 20:56:35 -05:00
configs.c update the email address of Randy Dunlap 2006-01-03 13:37:51 +01:00
cpu.c [PATCH] clean up lock_cpu_hotplug() in cpufreq 2005-11-28 14:42:23 -08:00
cpuset.c [PATCH] cpuset: remove useless local variable initialization 2006-03-24 07:33:24 -08:00
dma.c Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
exec_domain.c [PATCH] Fix module refcount leak in __set_personality() 2006-03-24 07:33:30 -08:00
exit.c [PATCH] sem2mutex: tty 2006-03-23 07:38:11 -08:00
extable.c Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
fork.c [PATCH] cpuset memory spread slab cache optimizations 2006-03-24 07:33:23 -08:00
futex.c [PATCH] FRV: Make futex code compilable on nommu [try #2] 2006-01-06 08:33:33 -08:00
hrtimer.c [PATCH] fix next_timer_interrupt() for hrtimer 2006-03-06 18:40:44 -08:00
intermodule.c [PATCH] missing license tag in intermodule 2006-02-05 11:06:52 -08:00
itimer.c [PATCH] Validate and sanitze itimer timeval from userspace 2006-03-25 08:22:49 -08:00
kallsyms.c [PATCH] fix missing includes 2005-10-30 17:37:32 -08:00
Kconfig.hz [PATCH] i386: Selectable Frequency of the Timer Interrupt 2005-06-23 09:45:10 -07:00
Kconfig.preempt [PATCH] sched: voluntary kernel preemption 2005-06-25 16:24:45 -07:00
kexec.c [PATCH] move capable() to capability.h 2006-01-11 18:42:13 -08:00
kfifo.c [PATCH] gfp flags annotations - part 1 2005-10-08 15:00:57 -07:00
kmod.c [PATCH] Keys: Get rid of warning in kmod.c if keys disabled 2005-10-30 17:37:23 -08:00
kprobes.c [PATCH] sem2mutex: kprobes 2006-03-23 07:38:12 -08:00
ksysfs.c [PATCH] fix build error if CONFIG_SYSFS=n 2006-03-24 07:33:31 -08:00
kthread.c [PATCH] find_task_by_pid() needs tasklist_lock 2006-03-25 08:22:57 -08:00
Makefile [PATCH] relay: migrate from relayfs to a generic relay API 2006-03-23 19:56:55 +01:00
module.c [PATCH] Remove MODULE_PARM 2006-03-25 08:22:52 -08:00
mutex-debug.c [PATCH] fix/simplify mutex debugging code 2006-01-11 08:14:16 -08:00
mutex-debug.h [PATCH] mutex subsystem, debugging code 2006-01-09 15:59:20 -08:00
mutex.c [PATCH] mutex: trivial whitespace cleanups 2006-01-10 14:27:59 -08:00
mutex.h [PATCH] mutex subsystem, core 2006-01-09 15:59:19 -08:00
panic.c [PATCH] pause_on_oops command line option 2006-03-23 07:38:16 -08:00
params.c [PATCH] kernel/params.c: make param_array() static 2006-03-25 08:22:52 -08:00
pid.c [PATCH] RCU signal handling 2006-01-08 20:13:40 -08:00
posix-cpu-timers.c [PATCH] hrtimer: switch clock_nanosleep to hrtimer nanosleep API 2006-01-10 08:01:38 -08:00
posix-timers.c [PATCH] sem2mutex: kernel/ 2006-03-23 07:38:10 -08:00
printk.c [PATCH] console_setup() depends (wrongly?) on CONFIG_PRINTK 2006-03-24 07:33:27 -08:00
profile.c [PATCH] sem2mutex: kernel/ 2006-03-23 07:38:10 -08:00
ptrace.c [PATCH] fix zap_thread's ptrace related problems 2006-02-15 11:05:43 -08:00
rcupdate.c [PATCH] rcu_process_callbacks: don't cli() while testing ->nxtlist 2006-03-24 07:33:20 -08:00
rcutorture.c [PATCH] Remove MODULE_PARM 2006-03-25 08:22:52 -08:00
relay.c [PATCH] relay: consolidate sendfile() and read() code 2006-03-23 19:58:45 +01:00
resource.c [PATCH] kernel/resource.c: __check_region(): remove pointless __deprecated 2006-01-10 08:02:02 -08:00
sched.c [PATCH] make bug messages more consistent 2006-03-23 07:38:16 -08:00
seccomp.c Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
signal.c [PATCH] sigprocmask: kill unneeded temp var 2006-03-23 07:38:15 -08:00
softirq.c [PATCH] on_each_cpu(): disable local interrupts 2006-03-22 07:53:59 -08:00
softlockup.c [PATCH] timer irq driven soft watchdog fix 2006-03-25 08:22:48 -08:00
spinlock.c [PATCH] BUILD_LOCK_OPS: cleanup preempt_disable() usage 2006-03-23 07:38:16 -08:00
stop_machine.c [PATCH] Remove set_fs() in stop_machine() 2006-01-10 08:01:25 -08:00
sys_ni.c [PATCH] Fix compile for CONFIG_SYSVIPC=n or CONFIG_SYSCTL=n 2006-02-20 20:00:11 -08:00
sys.c [PATCH] No need to protect current->group_info in sys_getgroups(), in_group_p() and in_egroup_p() 2006-03-25 08:22:58 -08:00
sysctl.c [PATCH] Range checking in do_proc_dointvec_(userhz_)jiffies_conv 2006-03-24 07:33:20 -08:00
time.c [PATCH] Normalize timespec for negative values in ns_to_timespec 2006-02-03 08:32:06 -08:00
timer.c [PATCH] sys_alarm() unsigned signed conversion fixup 2006-03-25 08:22:48 -08:00
uid16.c [PATCH] move capable() to capability.h 2006-01-11 18:42:13 -08:00
user.c [PATCH] free_uid() locking improvement 2006-03-24 07:33:20 -08:00
wait.c Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
workqueue.c [SCSI] add execute_in_process_context() API 2006-02-27 23:34:40 -06:00