On Thu, Feb 20, 2014 at 02:16:00AM +0400, Kirill Tkhai wrote:
> Since deadline tasks share rt bandwidth, we must care about
> bandwidth timer set. Otherwise rt_time may grow up to infinity
> in update_curr_dl(), if there are no other available RT tasks
> on top level bandwidth.
>
> I'm going to decide the problem the way below. Almost untested
> because of I skipped almost all of recent patches which haveto be applied
> from lkml.
>
> Please say, if I skipped anything in idea. Maybe better put
> start_top_rt_bandwidth() into set_curr_task_dl()?
How about we only increment rt_time when there's an RT bandwidth timer
active?
---
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -568,6 +568,12 @@ static inline struct rt_bandwidth *sched
#endif /* CONFIG_RT_GROUP_SCHED */
+bool sched_rt_bandwidth_active(struct rt_rq *rt_rq)
+{
+ struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
+ return hrtimer_active(&rt_b->rt_period_timer);
+}
+
#ifdef CONFIG_SMP
/*
* We ran out of runtime, see if we can borrow some from our neighbours.
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -587,6 +587,8 @@ int dl_runtime_exceeded(struct rq *rq, s
return 1;
}
+extern bool sched_rt_bandwidth_active(struct rt_rq *rt_rq);
+
/*
* Update the current task's runtime statistics (provided it is still
* a -deadline task and has not been removed from the dl_rq).
@@ -650,11 +652,13 @@ static void update_curr_dl(struct rq *rq
struct rt_rq *rt_rq = &rq->rt;
raw_spin_lock(&rt_rq->rt_runtime_lock);
- rt_rq->rt_time += delta_exec;
/*
* We'll let actual RT tasks worry about the overflow here, we
- * have our own CBS to keep us inline -- see above.
+ * have our own CBS to keep us inline; only account when RT
+ * bandwidth is relevant.
*/
+ if (sched_rt_bandwidth_active(rt_rq))
+ rt_rq->rt_time += delta_exec;
raw_spin_unlock(&rt_rq->rt_runtime_lock);
}
}
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