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| author | Gregory Haskins <ghaskins@novell.com> | 2008-04-23 07:13:29 -0400 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2008-05-05 23:56:18 +0200 |
| commit | 8ae121ac8666b0421aa20fd80d4597ec66fa54bc (patch) | |
| tree | 1db411965b1b12029d501ea10ab90fbc8aa4ec62 | |
| parent | 983ed7a66bcec9dc307d89dc7af47cdf209e56af (diff) | |
| download | linux-8ae121ac8666b0421aa20fd80d4597ec66fa54bc.tar.gz linux-8ae121ac8666b0421aa20fd80d4597ec66fa54bc.tar.bz2 linux-8ae121ac8666b0421aa20fd80d4597ec66fa54bc.zip | |
sched: fix RT task-wakeup logic
Dmitry Adamushko pointed out a logic error in task_wake_up_rt() where we
will always evaluate to "true". You can find the thread here:
http://lkml.org/lkml/2008/4/22/296
In reality, we only want to try to push tasks away when a wake up request is
not going to preempt the current task. So lets fix it.
Note: We introduce test_tsk_need_resched() instead of open-coding the flag
check so that the merge-conflict with -rt should help remind us that we
may need to support NEEDS_RESCHED_DELAYED in the future, too.
Signed-off-by: Gregory Haskins <ghaskins@novell.com>
CC: Dmitry Adamushko <dmitry.adamushko@gmail.com>
CC: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
| -rw-r--r-- | include/linux/sched.h | 7 | ||||
| -rw-r--r-- | kernel/sched_rt.c | 7 |
2 files changed, 11 insertions, 3 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h index 03c238088aee..698b5a4d25a7 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1977,6 +1977,11 @@ static inline void clear_tsk_need_resched(struct task_struct *tsk) clear_tsk_thread_flag(tsk,TIF_NEED_RESCHED); } +static inline int test_tsk_need_resched(struct task_struct *tsk) +{ + return unlikely(test_tsk_thread_flag(tsk,TIF_NEED_RESCHED)); +} + static inline int signal_pending(struct task_struct *p) { return unlikely(test_tsk_thread_flag(p,TIF_SIGPENDING)); @@ -1991,7 +1996,7 @@ static inline int fatal_signal_pending(struct task_struct *p) static inline int need_resched(void) { - return unlikely(test_thread_flag(TIF_NEED_RESCHED)); + return unlikely(test_tsk_need_resched(current)); } /* diff --git a/kernel/sched_rt.c b/kernel/sched_rt.c index dcd649588593..060e87b0cb1c 100644 --- a/kernel/sched_rt.c +++ b/kernel/sched_rt.c @@ -1098,11 +1098,14 @@ static void post_schedule_rt(struct rq *rq) } } - +/* + * If we are not running and we are not going to reschedule soon, we should + * try to push tasks away now + */ static void task_wake_up_rt(struct rq *rq, struct task_struct *p) { if (!task_running(rq, p) && - (p->prio >= rq->rt.highest_prio) && + !test_tsk_need_resched(rq->curr) && rq->rt.overloaded) push_rt_tasks(rq); } |