diff options
| author | Thomas Gleixner <tglx@linutronix.de> | 2009-07-03 08:44:44 -0500 |
|---|---|---|
| committer | Clark Williams <williams@redhat.com> | 2012-03-07 16:15:00 -0600 |
| commit | 0abfdf1e36c2d224fbe2e13584e593e8df3c513f (patch) | |
| tree | 2f05b27d9eb47b7df2687b8ba0d93124a73565d8 /kernel/posix-cpu-timers.c | |
| parent | 90de63bdd69c5de9d3da6555c1fa13a95d80e0a0 (diff) | |
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>
Diffstat (limited to 'kernel/posix-cpu-timers.c')
| -rw-r--r-- | kernel/posix-cpu-timers.c | 21 |
1 files changed, 18 insertions, 3 deletions
diff --git a/kernel/posix-cpu-timers.c b/kernel/posix-cpu-timers.c index fb350d745241..1d4c6096395a 100644 --- a/kernel/posix-cpu-timers.c +++ b/kernel/posix-cpu-timers.c @@ -1436,6 +1436,21 @@ 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(); @@ -1448,7 +1463,7 @@ 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; @@ -1460,9 +1475,9 @@ 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)); } /* |