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-rw-r--r--kernel/sched/rt.c108
1 files changed, 60 insertions, 48 deletions
diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index 575da76a3874..0d193a243e96 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -18,19 +18,22 @@ static enum hrtimer_restart sched_rt_period_timer(struct hrtimer *timer)
{
struct rt_bandwidth *rt_b =
container_of(timer, struct rt_bandwidth, rt_period_timer);
- ktime_t now;
- int overrun;
int idle = 0;
+ int overrun;
+ raw_spin_lock(&rt_b->rt_runtime_lock);
for (;;) {
- now = hrtimer_cb_get_time(timer);
- overrun = hrtimer_forward(timer, now, rt_b->rt_period);
-
+ overrun = hrtimer_forward_now(timer, rt_b->rt_period);
if (!overrun)
break;
+ raw_spin_unlock(&rt_b->rt_runtime_lock);
idle = do_sched_rt_period_timer(rt_b, overrun);
+ raw_spin_lock(&rt_b->rt_runtime_lock);
}
+ if (idle)
+ rt_b->rt_period_active = 0;
+ raw_spin_unlock(&rt_b->rt_runtime_lock);
return idle ? HRTIMER_NORESTART : HRTIMER_RESTART;
}
@@ -52,11 +55,12 @@ static void start_rt_bandwidth(struct rt_bandwidth *rt_b)
if (!rt_bandwidth_enabled() || rt_b->rt_runtime == RUNTIME_INF)
return;
- if (hrtimer_active(&rt_b->rt_period_timer))
- return;
-
raw_spin_lock(&rt_b->rt_runtime_lock);
- start_bandwidth_timer(&rt_b->rt_period_timer, rt_b->rt_period);
+ if (!rt_b->rt_period_active) {
+ rt_b->rt_period_active = 1;
+ hrtimer_forward_now(&rt_b->rt_period_timer, rt_b->rt_period);
+ hrtimer_start_expires(&rt_b->rt_period_timer, HRTIMER_MODE_ABS_PINNED);
+ }
raw_spin_unlock(&rt_b->rt_runtime_lock);
}
@@ -256,7 +260,7 @@ int alloc_rt_sched_group(struct task_group *tg, struct task_group *parent)
#ifdef CONFIG_SMP
-static int pull_rt_task(struct rq *this_rq);
+static void pull_rt_task(struct rq *this_rq);
static inline bool need_pull_rt_task(struct rq *rq, struct task_struct *prev)
{
@@ -350,13 +354,23 @@ static inline int has_pushable_tasks(struct rq *rq)
return !plist_head_empty(&rq->rt.pushable_tasks);
}
-static inline void set_post_schedule(struct rq *rq)
+static DEFINE_PER_CPU(struct callback_head, rt_push_head);
+static DEFINE_PER_CPU(struct callback_head, rt_pull_head);
+
+static void push_rt_tasks(struct rq *);
+static void pull_rt_task(struct rq *);
+
+static inline void queue_push_tasks(struct rq *rq)
{
- /*
- * We detect this state here so that we can avoid taking the RQ
- * lock again later if there is no need to push
- */
- rq->post_schedule = has_pushable_tasks(rq);
+ if (!has_pushable_tasks(rq))
+ return;
+
+ queue_balance_callback(rq, &per_cpu(rt_push_head, rq->cpu), push_rt_tasks);
+}
+
+static inline void queue_pull_task(struct rq *rq)
+{
+ queue_balance_callback(rq, &per_cpu(rt_pull_head, rq->cpu), pull_rt_task);
}
static void enqueue_pushable_task(struct rq *rq, struct task_struct *p)
@@ -408,12 +422,11 @@ static inline bool need_pull_rt_task(struct rq *rq, struct task_struct *prev)
return false;
}
-static inline int pull_rt_task(struct rq *this_rq)
+static inline void pull_rt_task(struct rq *this_rq)
{
- return 0;
}
-static inline void set_post_schedule(struct rq *rq)
+static inline void queue_push_tasks(struct rq *rq)
{
}
#endif /* CONFIG_SMP */
@@ -1323,7 +1336,7 @@ select_task_rq_rt(struct task_struct *p, int cpu, int sd_flag, int flags)
rq = cpu_rq(cpu);
rcu_read_lock();
- curr = ACCESS_ONCE(rq->curr); /* unlocked access */
+ curr = READ_ONCE(rq->curr); /* unlocked access */
/*
* If the current task on @p's runqueue is an RT task, then
@@ -1465,7 +1478,15 @@ pick_next_task_rt(struct rq *rq, struct task_struct *prev)
struct rt_rq *rt_rq = &rq->rt;
if (need_pull_rt_task(rq, prev)) {
+ /*
+ * This is OK, because current is on_cpu, which avoids it being
+ * picked for load-balance and preemption/IRQs are still
+ * disabled avoiding further scheduler activity on it and we're
+ * being very careful to re-start the picking loop.
+ */
+ lockdep_unpin_lock(&rq->lock);
pull_rt_task(rq);
+ lockdep_pin_lock(&rq->lock);
/*
* pull_rt_task() can drop (and re-acquire) rq->lock; this
* means a dl or stop task can slip in, in which case we need
@@ -1493,7 +1514,7 @@ pick_next_task_rt(struct rq *rq, struct task_struct *prev)
/* The running task is never eligible for pushing */
dequeue_pushable_task(rq, p);
- set_post_schedule(rq);
+ queue_push_tasks(rq);
return p;
}
@@ -1948,14 +1969,15 @@ static void push_irq_work_func(struct irq_work *work)
}
#endif /* HAVE_RT_PUSH_IPI */
-static int pull_rt_task(struct rq *this_rq)
+static void pull_rt_task(struct rq *this_rq)
{
- int this_cpu = this_rq->cpu, ret = 0, cpu;
+ int this_cpu = this_rq->cpu, cpu;
+ bool resched = false;
struct task_struct *p;
struct rq *src_rq;
if (likely(!rt_overloaded(this_rq)))
- return 0;
+ return;
/*
* Match the barrier from rt_set_overloaded; this guarantees that if we
@@ -1966,7 +1988,7 @@ static int pull_rt_task(struct rq *this_rq)
#ifdef HAVE_RT_PUSH_IPI
if (sched_feat(RT_PUSH_IPI)) {
tell_cpu_to_push(this_rq);
- return 0;
+ return;
}
#endif
@@ -2019,7 +2041,7 @@ static int pull_rt_task(struct rq *this_rq)
if (p->prio < src_rq->curr->prio)
goto skip;
- ret = 1;
+ resched = true;
deactivate_task(src_rq, p, 0);
set_task_cpu(p, this_cpu);
@@ -2035,12 +2057,8 @@ skip:
double_unlock_balance(this_rq, src_rq);
}
- return ret;
-}
-
-static void post_schedule_rt(struct rq *rq)
-{
- push_rt_tasks(rq);
+ if (resched)
+ resched_curr(this_rq);
}
/*
@@ -2136,8 +2154,7 @@ static void switched_from_rt(struct rq *rq, struct task_struct *p)
if (!task_on_rq_queued(p) || rq->rt.rt_nr_running)
return;
- if (pull_rt_task(rq))
- resched_curr(rq);
+ queue_pull_task(rq);
}
void __init init_sched_rt_class(void)
@@ -2158,8 +2175,6 @@ void __init init_sched_rt_class(void)
*/
static void switched_to_rt(struct rq *rq, struct task_struct *p)
{
- int check_resched = 1;
-
/*
* If we are already running, then there's nothing
* that needs to be done. But if we are not running
@@ -2169,13 +2184,12 @@ static void switched_to_rt(struct rq *rq, struct task_struct *p)
*/
if (task_on_rq_queued(p) && rq->curr != p) {
#ifdef CONFIG_SMP
- if (p->nr_cpus_allowed > 1 && rq->rt.overloaded &&
- /* Don't resched if we changed runqueues */
- push_rt_task(rq) && rq != task_rq(p))
- check_resched = 0;
-#endif /* CONFIG_SMP */
- if (check_resched && p->prio < rq->curr->prio)
+ if (p->nr_cpus_allowed > 1 && rq->rt.overloaded)
+ queue_push_tasks(rq);
+#else
+ if (p->prio < rq->curr->prio)
resched_curr(rq);
+#endif /* CONFIG_SMP */
}
}
@@ -2196,14 +2210,13 @@ prio_changed_rt(struct rq *rq, struct task_struct *p, int oldprio)
* may need to pull tasks to this runqueue.
*/
if (oldprio < p->prio)
- pull_rt_task(rq);
+ queue_pull_task(rq);
+
/*
* If there's a higher priority task waiting to run
- * then reschedule. Note, the above pull_rt_task
- * can release the rq lock and p could migrate.
- * Only reschedule if p is still on the same runqueue.
+ * then reschedule.
*/
- if (p->prio > rq->rt.highest_prio.curr && rq->curr == p)
+ if (p->prio > rq->rt.highest_prio.curr)
resched_curr(rq);
#else
/* For UP simply resched on drop of prio */
@@ -2314,7 +2327,6 @@ const struct sched_class rt_sched_class = {
.set_cpus_allowed = set_cpus_allowed_rt,
.rq_online = rq_online_rt,
.rq_offline = rq_offline_rt,
- .post_schedule = post_schedule_rt,
.task_woken = task_woken_rt,
.switched_from = switched_from_rt,
#endif