diff options
author | Thomas Gleixner <tglx@linutronix.de> | 2009-07-03 08:44:44 -0500 |
---|---|---|
committer | Clark Williams <williams@redhat.com> | 2011-12-28 16:25:36 -0600 |
commit | b89376378f9a89f59f9feb940f422ce1e47cdd92 (patch) | |
tree | a89f1bf3340a9c7c3c4a8a00b1a66f7b831ec8d2 | |
parent | 2e0e6dec33cbad4c43425dee7b72448ccf4fc282 (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>
-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)); } /* |