diff options
Diffstat (limited to 'kernel/sched/rt.c')
| -rw-r--r-- | kernel/sched/rt.c | 108 |
1 files changed, 60 insertions, 48 deletions
diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c index 575da76a3..0d193a243 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 |