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Message-Id: <230991392848160@web13m.yandex.ru>
Date: Thu, 20 Feb 2014 02:16:00 +0400
From: Kirill Tkhai <tkhai@...dex.ru>
To: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Cc: Juri Lelli <juri.lelli@...il.com>,
Peter Zijlstra <peterz@...radead.org>,
Steven Rostedt <rostedt@...dmis.org>,
Ingo Molnar <mingo@...hat.com>
Subject: [RFC] sched/deadline: Prevent rt_time growth to infinity
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()?
---
kernel/sched/deadline.c | 1 +
kernel/sched/rt.c | 16 +++++++++++++++-
kernel/sched/sched.h | 1 +
3 files changed, 17 insertions(+), 1 deletion(-)
diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index ed31ef6..f1d2304 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -720,6 +720,7 @@ void inc_dl_tasks(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
inc_dl_deadline(dl_rq, deadline);
inc_dl_migration(dl_se, dl_rq);
+ start_top_rt_bandwidth(rq_of_dl_rq(dl_rq));
}
static inline
diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index 72f9ec7..a187eb8 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -726,7 +726,7 @@ static inline int balance_runtime(struct rt_rq *rt_rq)
static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun)
{
- int i, idle = 1, throttled = 0;
+ int i, idle = 1, throttled = 0, has_dl_tasks = 0;
const struct cpumask *span;
span = sched_rt_period_mask();
@@ -781,9 +781,15 @@ static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun)
if (enqueue)
sched_rt_rq_enqueue(rt_rq);
+
+ if (rt_rq == &rq->rt && rq->dl.dl_nr_running)
+ has_dl_tasks = 1;
raw_spin_unlock(&rq->lock);
}
+ if (has_dl_tasks)
+ return 0;
+
if (!throttled && (!rt_bandwidth_enabled() || rt_b->rt_runtime == RUNTIME_INF))
return 1;
@@ -1005,6 +1011,10 @@ dec_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
WARN_ON(!rt_rq->rt_nr_running && rt_rq->rt_nr_boosted);
}
+void start_top_rt_bandwidth(struct rq *rq)
+{
+ start_rt_bandwidth(&rq->rt.tg->rt_bandwidth);
+}
#else /* CONFIG_RT_GROUP_SCHED */
static void
@@ -1016,6 +1026,10 @@ inc_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
static inline
void dec_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq) {}
+void start_top_rt_bandwidth(struct rq *rq)
+{
+ start_rt_bandwidth(&def_rt_bandwidth);
+}
#endif /* CONFIG_RT_GROUP_SCHED */
static inline
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 1bf34c2..a20f8f7 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -1294,6 +1294,7 @@ static inline void sched_avg_update(struct rq *rq) { }
#endif
extern void start_bandwidth_timer(struct hrtimer *period_timer, ktime_t period);
+extern void start_top_rt_bandwidth(struct rq *rq);
#ifdef CONFIG_SMP
#ifdef CONFIG_PREEMPT
--
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