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posix-timers: Avoid wakeups when no timers are active 

Waking the thread even when no timers are scheduled is useless.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Thomas Gleixner 2009-07-03 08:44:44 -05:00 committed by Alibek Omarov
parent 6af028f471
commit e2a43807d9
1 changed files with 18 additions and 3 deletions
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21
kernel/posix-cpu-timers.c
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@ -1274,6 +1274,21 @@ wait_to_die:
return 0;
}
static inline int __fastpath_timer_check(struct task_struct *tsk)
{
/* tsk == current, ensure it is safe to use ->signal/sighand */
if (unlikely(tsk->exit_state))
return 0;
if (!task_cputime_zero(&tsk->cputime_expires))
return 1;
if (!task_cputime_zero(&tsk->signal->cputime_expires))
return 1;
return 0;
}
void run_posix_cpu_timers(struct task_struct *tsk)
{
unsigned long cpu = smp_processor_id();
@ -1286,7 +1301,7 @@ void run_posix_cpu_timers(struct task_struct *tsk)
tasklist = per_cpu(posix_timer_tasklist, cpu);
/* check to see if we're already queued */
if (!tsk->posix_timer_list) {
if (!tsk->posix_timer_list && __fastpath_timer_check(tsk)) {
get_task_struct(tsk);
if (tasklist) {
tsk->posix_timer_list = tasklist;
@ -1298,9 +1313,9 @@ void run_posix_cpu_timers(struct task_struct *tsk)
tsk->posix_timer_list = tsk;
}
per_cpu(posix_timer_tasklist, cpu) = tsk;
wake_up_process(per_cpu(posix_timer_task, cpu));
}
/* XXX signal the thread somehow */
wake_up_process(per_cpu(posix_timer_task, cpu));
}
/*