rt.c 47.1 KB
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/*
 * Real-Time Scheduling Class (mapped to the SCHED_FIFO and SCHED_RR
 * policies)
 */

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#include "sched.h"

#include <linux/slab.h>

static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun);

struct rt_bandwidth def_rt_bandwidth;

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;

	for (;;) {
		now = hrtimer_cb_get_time(timer);
		overrun = hrtimer_forward(timer, now, rt_b->rt_period);

		if (!overrun)
			break;

		idle = do_sched_rt_period_timer(rt_b, overrun);
	}

	return idle ? HRTIMER_NORESTART : HRTIMER_RESTART;
}

void init_rt_bandwidth(struct rt_bandwidth *rt_b, u64 period, u64 runtime)
{
	rt_b->rt_period = ns_to_ktime(period);
	rt_b->rt_runtime = runtime;

	raw_spin_lock_init(&rt_b->rt_runtime_lock);

	hrtimer_init(&rt_b->rt_period_timer,
			CLOCK_MONOTONIC, HRTIMER_MODE_REL);
	rt_b->rt_period_timer.function = sched_rt_period_timer;
}

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);
	raw_spin_unlock(&rt_b->rt_runtime_lock);
}

void init_rt_rq(struct rt_rq *rt_rq, struct rq *rq)
{
	struct rt_prio_array *array;
	int i;

	array = &rt_rq->active;
	for (i = 0; i < MAX_RT_PRIO; i++) {
		INIT_LIST_HEAD(array->queue + i);
		__clear_bit(i, array->bitmap);
	}
	/* delimiter for bitsearch: */
	__set_bit(MAX_RT_PRIO, array->bitmap);

#if defined CONFIG_SMP
	rt_rq->highest_prio.curr = MAX_RT_PRIO;
	rt_rq->highest_prio.next = MAX_RT_PRIO;
	rt_rq->rt_nr_migratory = 0;
	rt_rq->overloaded = 0;
	plist_head_init(&rt_rq->pushable_tasks);
#endif

	rt_rq->rt_time = 0;
	rt_rq->rt_throttled = 0;
	rt_rq->rt_runtime = 0;
	raw_spin_lock_init(&rt_rq->rt_runtime_lock);
}

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#ifdef CONFIG_RT_GROUP_SCHED
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static void destroy_rt_bandwidth(struct rt_bandwidth *rt_b)
{
	hrtimer_cancel(&rt_b->rt_period_timer);
}
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#define rt_entity_is_task(rt_se) (!(rt_se)->my_q)

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static inline struct task_struct *rt_task_of(struct sched_rt_entity *rt_se)
{
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#ifdef CONFIG_SCHED_DEBUG
	WARN_ON_ONCE(!rt_entity_is_task(rt_se));
#endif
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	return container_of(rt_se, struct task_struct, rt);
}

static inline struct rq *rq_of_rt_rq(struct rt_rq *rt_rq)
{
	return rt_rq->rq;
}

static inline struct rt_rq *rt_rq_of_se(struct sched_rt_entity *rt_se)
{
	return rt_se->rt_rq;
}

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void free_rt_sched_group(struct task_group *tg)
{
	int i;

	if (tg->rt_se)
		destroy_rt_bandwidth(&tg->rt_bandwidth);

	for_each_possible_cpu(i) {
		if (tg->rt_rq)
			kfree(tg->rt_rq[i]);
		if (tg->rt_se)
			kfree(tg->rt_se[i]);
	}

	kfree(tg->rt_rq);
	kfree(tg->rt_se);
}

void init_tg_rt_entry(struct task_group *tg, struct rt_rq *rt_rq,
		struct sched_rt_entity *rt_se, int cpu,
		struct sched_rt_entity *parent)
{
	struct rq *rq = cpu_rq(cpu);

	rt_rq->highest_prio.curr = MAX_RT_PRIO;
	rt_rq->rt_nr_boosted = 0;
	rt_rq->rq = rq;
	rt_rq->tg = tg;

	tg->rt_rq[cpu] = rt_rq;
	tg->rt_se[cpu] = rt_se;

	if (!rt_se)
		return;

	if (!parent)
		rt_se->rt_rq = &rq->rt;
	else
		rt_se->rt_rq = parent->my_q;

	rt_se->my_q = rt_rq;
	rt_se->parent = parent;
	INIT_LIST_HEAD(&rt_se->run_list);
}

int alloc_rt_sched_group(struct task_group *tg, struct task_group *parent)
{
	struct rt_rq *rt_rq;
	struct sched_rt_entity *rt_se;
	int i;

	tg->rt_rq = kzalloc(sizeof(rt_rq) * nr_cpu_ids, GFP_KERNEL);
	if (!tg->rt_rq)
		goto err;
	tg->rt_se = kzalloc(sizeof(rt_se) * nr_cpu_ids, GFP_KERNEL);
	if (!tg->rt_se)
		goto err;

	init_rt_bandwidth(&tg->rt_bandwidth,
			ktime_to_ns(def_rt_bandwidth.rt_period), 0);

	for_each_possible_cpu(i) {
		rt_rq = kzalloc_node(sizeof(struct rt_rq),
				     GFP_KERNEL, cpu_to_node(i));
		if (!rt_rq)
			goto err;

		rt_se = kzalloc_node(sizeof(struct sched_rt_entity),
				     GFP_KERNEL, cpu_to_node(i));
		if (!rt_se)
			goto err_free_rq;

		init_rt_rq(rt_rq, cpu_rq(i));
		rt_rq->rt_runtime = tg->rt_bandwidth.rt_runtime;
		init_tg_rt_entry(tg, rt_rq, rt_se, i, parent->rt_se[i]);
	}

	return 1;

err_free_rq:
	kfree(rt_rq);
err:
	return 0;
}

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#else /* CONFIG_RT_GROUP_SCHED */

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#define rt_entity_is_task(rt_se) (1)

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static inline struct task_struct *rt_task_of(struct sched_rt_entity *rt_se)
{
	return container_of(rt_se, struct task_struct, rt);
}

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static inline struct rq *rq_of_rt_rq(struct rt_rq *rt_rq)
{
	return container_of(rt_rq, struct rq, rt);
}

static inline struct rt_rq *rt_rq_of_se(struct sched_rt_entity *rt_se)
{
	struct task_struct *p = rt_task_of(rt_se);
	struct rq *rq = task_rq(p);

	return &rq->rt;
}

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void free_rt_sched_group(struct task_group *tg) { }

int alloc_rt_sched_group(struct task_group *tg, struct task_group *parent)
{
	return 1;
}
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#endif /* CONFIG_RT_GROUP_SCHED */

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#ifdef CONFIG_SMP
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static inline int rt_overloaded(struct rq *rq)
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{
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	return atomic_read(&rq->rd->rto_count);
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}
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static inline void rt_set_overload(struct rq *rq)
{
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	if (!rq->online)
		return;

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	cpumask_set_cpu(rq->cpu, rq->rd->rto_mask);
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	/*
	 * Make sure the mask is visible before we set
	 * the overload count. That is checked to determine
	 * if we should look at the mask. It would be a shame
	 * if we looked at the mask, but the mask was not
	 * updated yet.
	 */
	wmb();
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	atomic_inc(&rq->rd->rto_count);
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}
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static inline void rt_clear_overload(struct rq *rq)
{
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	if (!rq->online)
		return;

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	/* the order here really doesn't matter */
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	atomic_dec(&rq->rd->rto_count);
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	cpumask_clear_cpu(rq->cpu, rq->rd->rto_mask);
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}
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static void update_rt_migration(struct rt_rq *rt_rq)
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{
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	if (rt_rq->rt_nr_migratory && rt_rq->rt_nr_total > 1) {
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		if (!rt_rq->overloaded) {
			rt_set_overload(rq_of_rt_rq(rt_rq));
			rt_rq->overloaded = 1;
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		}
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	} else if (rt_rq->overloaded) {
		rt_clear_overload(rq_of_rt_rq(rt_rq));
		rt_rq->overloaded = 0;
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	}
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}
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static void inc_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
{
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	struct task_struct *p;

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	if (!rt_entity_is_task(rt_se))
		return;

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	p = rt_task_of(rt_se);
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	rt_rq = &rq_of_rt_rq(rt_rq)->rt;

	rt_rq->rt_nr_total++;
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	if (p->nr_cpus_allowed > 1)
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		rt_rq->rt_nr_migratory++;

	update_rt_migration(rt_rq);
}

static void dec_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
{
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	struct task_struct *p;

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	if (!rt_entity_is_task(rt_se))
		return;

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	p = rt_task_of(rt_se);
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	rt_rq = &rq_of_rt_rq(rt_rq)->rt;

	rt_rq->rt_nr_total--;
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	if (p->nr_cpus_allowed > 1)
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		rt_rq->rt_nr_migratory--;

	update_rt_migration(rt_rq);
}

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static inline int has_pushable_tasks(struct rq *rq)
{
	return !plist_head_empty(&rq->rt.pushable_tasks);
}

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static void enqueue_pushable_task(struct rq *rq, struct task_struct *p)
{
	plist_del(&p->pushable_tasks, &rq->rt.pushable_tasks);
	plist_node_init(&p->pushable_tasks, p->prio);
	plist_add(&p->pushable_tasks, &rq->rt.pushable_tasks);
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	/* Update the highest prio pushable task */
	if (p->prio < rq->rt.highest_prio.next)
		rq->rt.highest_prio.next = p->prio;
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}

static void dequeue_pushable_task(struct rq *rq, struct task_struct *p)
{
	plist_del(&p->pushable_tasks, &rq->rt.pushable_tasks);

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	/* Update the new highest prio pushable task */
	if (has_pushable_tasks(rq)) {
		p = plist_first_entry(&rq->rt.pushable_tasks,
				      struct task_struct, pushable_tasks);
		rq->rt.highest_prio.next = p->prio;
	} else
		rq->rt.highest_prio.next = MAX_RT_PRIO;
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}

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#else

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static inline void enqueue_pushable_task(struct rq *rq, struct task_struct *p)
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{
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}

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static inline void dequeue_pushable_task(struct rq *rq, struct task_struct *p)
{
}

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static inline
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void inc_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
{
}

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static inline
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void dec_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
{
}
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#endif /* CONFIG_SMP */

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static inline int on_rt_rq(struct sched_rt_entity *rt_se)
{
	return !list_empty(&rt_se->run_list);
}

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#ifdef CONFIG_RT_GROUP_SCHED
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static inline u64 sched_rt_runtime(struct rt_rq *rt_rq)
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{
	if (!rt_rq->tg)
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		return RUNTIME_INF;
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	return rt_rq->rt_runtime;
}

static inline u64 sched_rt_period(struct rt_rq *rt_rq)
{
	return ktime_to_ns(rt_rq->tg->rt_bandwidth.rt_period);
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}

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typedef struct task_group *rt_rq_iter_t;

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static inline struct task_group *next_task_group(struct task_group *tg)
{
	do {
		tg = list_entry_rcu(tg->list.next,
			typeof(struct task_group), list);
	} while (&tg->list != &task_groups && task_group_is_autogroup(tg));

	if (&tg->list == &task_groups)
		tg = NULL;

	return tg;
}

#define for_each_rt_rq(rt_rq, iter, rq)					\
	for (iter = container_of(&task_groups, typeof(*iter), list);	\
		(iter = next_task_group(iter)) &&			\
		(rt_rq = iter->rt_rq[cpu_of(rq)]);)
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static inline void list_add_leaf_rt_rq(struct rt_rq *rt_rq)
{
	list_add_rcu(&rt_rq->leaf_rt_rq_list,
			&rq_of_rt_rq(rt_rq)->leaf_rt_rq_list);
}

static inline void list_del_leaf_rt_rq(struct rt_rq *rt_rq)
{
	list_del_rcu(&rt_rq->leaf_rt_rq_list);
}

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#define for_each_leaf_rt_rq(rt_rq, rq) \
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	list_for_each_entry_rcu(rt_rq, &rq->leaf_rt_rq_list, leaf_rt_rq_list)
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#define for_each_sched_rt_entity(rt_se) \
	for (; rt_se; rt_se = rt_se->parent)

static inline struct rt_rq *group_rt_rq(struct sched_rt_entity *rt_se)
{
	return rt_se->my_q;
}

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static void enqueue_rt_entity(struct sched_rt_entity *rt_se, bool head);
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static void dequeue_rt_entity(struct sched_rt_entity *rt_se);

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static void sched_rt_rq_enqueue(struct rt_rq *rt_rq)
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{
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	struct task_struct *curr = rq_of_rt_rq(rt_rq)->curr;
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	struct sched_rt_entity *rt_se;

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	int cpu = cpu_of(rq_of_rt_rq(rt_rq));

	rt_se = rt_rq->tg->rt_se[cpu];
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	if (rt_rq->rt_nr_running) {
		if (rt_se && !on_rt_rq(rt_se))
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			enqueue_rt_entity(rt_se, false);
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		if (rt_rq->highest_prio.curr < curr->prio)
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			resched_task(curr);
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	}
}

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static void sched_rt_rq_dequeue(struct rt_rq *rt_rq)
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{
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	struct sched_rt_entity *rt_se;
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	int cpu = cpu_of(rq_of_rt_rq(rt_rq));
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	rt_se = rt_rq->tg->rt_se[cpu];
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	if (rt_se && on_rt_rq(rt_se))
		dequeue_rt_entity(rt_se);
}

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static inline int rt_rq_throttled(struct rt_rq *rt_rq)
{
	return rt_rq->rt_throttled && !rt_rq->rt_nr_boosted;
}

static int rt_se_boosted(struct sched_rt_entity *rt_se)
{
	struct rt_rq *rt_rq = group_rt_rq(rt_se);
	struct task_struct *p;

	if (rt_rq)
		return !!rt_rq->rt_nr_boosted;

	p = rt_task_of(rt_se);
	return p->prio != p->normal_prio;
}

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#ifdef CONFIG_SMP
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static inline const struct cpumask *sched_rt_period_mask(void)
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{
	return cpu_rq(smp_processor_id())->rd->span;
}
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#else
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static inline const struct cpumask *sched_rt_period_mask(void)
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{
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	return cpu_online_mask;
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}
#endif
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static inline
struct rt_rq *sched_rt_period_rt_rq(struct rt_bandwidth *rt_b, int cpu)
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{
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	return container_of(rt_b, struct task_group, rt_bandwidth)->rt_rq[cpu];
}
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static inline struct rt_bandwidth *sched_rt_bandwidth(struct rt_rq *rt_rq)
{
	return &rt_rq->tg->rt_bandwidth;
}

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#else /* !CONFIG_RT_GROUP_SCHED */
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static inline u64 sched_rt_runtime(struct rt_rq *rt_rq)
{
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	return rt_rq->rt_runtime;
}

static inline u64 sched_rt_period(struct rt_rq *rt_rq)
{
	return ktime_to_ns(def_rt_bandwidth.rt_period);
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}

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typedef struct rt_rq *rt_rq_iter_t;

#define for_each_rt_rq(rt_rq, iter, rq) \
	for ((void) iter, rt_rq = &rq->rt; rt_rq; rt_rq = NULL)

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static inline void list_add_leaf_rt_rq(struct rt_rq *rt_rq)
{
}

static inline void list_del_leaf_rt_rq(struct rt_rq *rt_rq)
{
}

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#define for_each_leaf_rt_rq(rt_rq, rq) \
	for (rt_rq = &rq->rt; rt_rq; rt_rq = NULL)

#define for_each_sched_rt_entity(rt_se) \
	for (; rt_se; rt_se = NULL)

static inline struct rt_rq *group_rt_rq(struct sched_rt_entity *rt_se)
{
	return NULL;
}

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static inline void sched_rt_rq_enqueue(struct rt_rq *rt_rq)
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{
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	if (rt_rq->rt_nr_running)
		resched_task(rq_of_rt_rq(rt_rq)->curr);
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}

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static inline void sched_rt_rq_dequeue(struct rt_rq *rt_rq)
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{
}

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static inline int rt_rq_throttled(struct rt_rq *rt_rq)
{
	return rt_rq->rt_throttled;
}
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static inline const struct cpumask *sched_rt_period_mask(void)
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{
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	return cpu_online_mask;
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}

static inline
struct rt_rq *sched_rt_period_rt_rq(struct rt_bandwidth *rt_b, int cpu)
{
	return &cpu_rq(cpu)->rt;
}

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static inline struct rt_bandwidth *sched_rt_bandwidth(struct rt_rq *rt_rq)
{
	return &def_rt_bandwidth;
}

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#endif /* CONFIG_RT_GROUP_SCHED */
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#ifdef CONFIG_SMP
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/*
 * We ran out of runtime, see if we can borrow some from our neighbours.
 */
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static int do_balance_runtime(struct rt_rq *rt_rq)
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{
	struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
	struct root_domain *rd = cpu_rq(smp_processor_id())->rd;
	int i, weight, more = 0;
	u64 rt_period;

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	weight = cpumask_weight(rd->span);
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	raw_spin_lock(&rt_b->rt_runtime_lock);
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	rt_period = ktime_to_ns(rt_b->rt_period);
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	for_each_cpu(i, rd->span) {
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		struct rt_rq *iter = sched_rt_period_rt_rq(rt_b, i);
		s64 diff;

		if (iter == rt_rq)
			continue;

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		raw_spin_lock(&iter->rt_runtime_lock);
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		/*
		 * Either all rqs have inf runtime and there's nothing to steal
		 * or __disable_runtime() below sets a specific rq to inf to
		 * indicate its been disabled and disalow stealing.
		 */
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		if (iter->rt_runtime == RUNTIME_INF)
			goto next;

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		/*
		 * From runqueues with spare time, take 1/n part of their
		 * spare time, but no more than our period.
		 */
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		diff = iter->rt_runtime - iter->rt_time;
		if (diff > 0) {
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			diff = div_u64((u64)diff, weight);
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			if (rt_rq->rt_runtime + diff > rt_period)
				diff = rt_period - rt_rq->rt_runtime;
			iter->rt_runtime -= diff;
			rt_rq->rt_runtime += diff;
			more = 1;
			if (rt_rq->rt_runtime == rt_period) {
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				raw_spin_unlock(&iter->rt_runtime_lock);
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				break;
			}
		}
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next:
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		raw_spin_unlock(&iter->rt_runtime_lock);
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	}
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	raw_spin_unlock(&rt_b->rt_runtime_lock);
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614 615 616

	return more;
}
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617

618 619 620
/*
 * Ensure this RQ takes back all the runtime it lend to its neighbours.
 */
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621 622 623
static void __disable_runtime(struct rq *rq)
{
	struct root_domain *rd = rq->rd;
C
Cheng Xu 已提交
624
	rt_rq_iter_t iter;
P
Peter Zijlstra 已提交
625 626 627 628 629
	struct rt_rq *rt_rq;

	if (unlikely(!scheduler_running))
		return;

C
Cheng Xu 已提交
630
	for_each_rt_rq(rt_rq, iter, rq) {
P
Peter Zijlstra 已提交
631 632 633 634
		struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
		s64 want;
		int i;

635 636
		raw_spin_lock(&rt_b->rt_runtime_lock);
		raw_spin_lock(&rt_rq->rt_runtime_lock);
637 638 639 640 641
		/*
		 * Either we're all inf and nobody needs to borrow, or we're
		 * already disabled and thus have nothing to do, or we have
		 * exactly the right amount of runtime to take out.
		 */
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Peter Zijlstra 已提交
642 643 644
		if (rt_rq->rt_runtime == RUNTIME_INF ||
				rt_rq->rt_runtime == rt_b->rt_runtime)
			goto balanced;
645
		raw_spin_unlock(&rt_rq->rt_runtime_lock);
P
Peter Zijlstra 已提交
646

647 648 649 650 651
		/*
		 * Calculate the difference between what we started out with
		 * and what we current have, that's the amount of runtime
		 * we lend and now have to reclaim.
		 */
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Peter Zijlstra 已提交
652 653
		want = rt_b->rt_runtime - rt_rq->rt_runtime;

654 655 656
		/*
		 * Greedy reclaim, take back as much as we can.
		 */
657
		for_each_cpu(i, rd->span) {
P
Peter Zijlstra 已提交
658 659 660
			struct rt_rq *iter = sched_rt_period_rt_rq(rt_b, i);
			s64 diff;

661 662 663
			/*
			 * Can't reclaim from ourselves or disabled runqueues.
			 */
664
			if (iter == rt_rq || iter->rt_runtime == RUNTIME_INF)
P
Peter Zijlstra 已提交
665 666
				continue;

667
			raw_spin_lock(&iter->rt_runtime_lock);
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Peter Zijlstra 已提交
668 669 670 671 672 673 674 675
			if (want > 0) {
				diff = min_t(s64, iter->rt_runtime, want);
				iter->rt_runtime -= diff;
				want -= diff;
			} else {
				iter->rt_runtime -= want;
				want -= want;
			}
676
			raw_spin_unlock(&iter->rt_runtime_lock);
P
Peter Zijlstra 已提交
677 678 679 680 681

			if (!want)
				break;
		}

682
		raw_spin_lock(&rt_rq->rt_runtime_lock);
683 684 685 686
		/*
		 * We cannot be left wanting - that would mean some runtime
		 * leaked out of the system.
		 */
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Peter Zijlstra 已提交
687 688
		BUG_ON(want);
balanced:
689 690 691 692
		/*
		 * Disable all the borrow logic by pretending we have inf
		 * runtime - in which case borrowing doesn't make sense.
		 */
P
Peter Zijlstra 已提交
693
		rt_rq->rt_runtime = RUNTIME_INF;
694 695
		raw_spin_unlock(&rt_rq->rt_runtime_lock);
		raw_spin_unlock(&rt_b->rt_runtime_lock);
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Peter Zijlstra 已提交
696 697 698 699 700 701 702
	}
}

static void disable_runtime(struct rq *rq)
{
	unsigned long flags;

703
	raw_spin_lock_irqsave(&rq->lock, flags);
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Peter Zijlstra 已提交
704
	__disable_runtime(rq);
705
	raw_spin_unlock_irqrestore(&rq->lock, flags);
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706 707 708 709
}

static void __enable_runtime(struct rq *rq)
{
C
Cheng Xu 已提交
710
	rt_rq_iter_t iter;
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711 712 713 714 715
	struct rt_rq *rt_rq;

	if (unlikely(!scheduler_running))
		return;

716 717 718
	/*
	 * Reset each runqueue's bandwidth settings
	 */
C
Cheng Xu 已提交
719
	for_each_rt_rq(rt_rq, iter, rq) {
P
Peter Zijlstra 已提交
720 721
		struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);

722 723
		raw_spin_lock(&rt_b->rt_runtime_lock);
		raw_spin_lock(&rt_rq->rt_runtime_lock);
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Peter Zijlstra 已提交
724 725
		rt_rq->rt_runtime = rt_b->rt_runtime;
		rt_rq->rt_time = 0;
726
		rt_rq->rt_throttled = 0;
727 728
		raw_spin_unlock(&rt_rq->rt_runtime_lock);
		raw_spin_unlock(&rt_b->rt_runtime_lock);
P
Peter Zijlstra 已提交
729 730 731 732 733 734 735
	}
}

static void enable_runtime(struct rq *rq)
{
	unsigned long flags;

736
	raw_spin_lock_irqsave(&rq->lock, flags);
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Peter Zijlstra 已提交
737
	__enable_runtime(rq);
738
	raw_spin_unlock_irqrestore(&rq->lock, flags);
P
Peter Zijlstra 已提交
739 740
}

741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762
int update_runtime(struct notifier_block *nfb, unsigned long action, void *hcpu)
{
	int cpu = (int)(long)hcpu;

	switch (action) {
	case CPU_DOWN_PREPARE:
	case CPU_DOWN_PREPARE_FROZEN:
		disable_runtime(cpu_rq(cpu));
		return NOTIFY_OK;

	case CPU_DOWN_FAILED:
	case CPU_DOWN_FAILED_FROZEN:
	case CPU_ONLINE:
	case CPU_ONLINE_FROZEN:
		enable_runtime(cpu_rq(cpu));
		return NOTIFY_OK;

	default:
		return NOTIFY_DONE;
	}
}

763 764 765 766
static int balance_runtime(struct rt_rq *rt_rq)
{
	int more = 0;

767 768 769
	if (!sched_feat(RT_RUNTIME_SHARE))
		return more;

770
	if (rt_rq->rt_time > rt_rq->rt_runtime) {
771
		raw_spin_unlock(&rt_rq->rt_runtime_lock);
772
		more = do_balance_runtime(rt_rq);
773
		raw_spin_lock(&rt_rq->rt_runtime_lock);
774 775 776 777
	}

	return more;
}
778
#else /* !CONFIG_SMP */
779 780 781 782
static inline int balance_runtime(struct rt_rq *rt_rq)
{
	return 0;
}
783
#endif /* CONFIG_SMP */
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Peter Zijlstra 已提交
784

785 786
static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun)
{
787
	int i, idle = 1, throttled = 0;
788
	const struct cpumask *span;
789 790

	span = sched_rt_period_mask();
791 792 793 794 795 796 797 798 799 800 801 802 803
#ifdef CONFIG_RT_GROUP_SCHED
	/*
	 * FIXME: isolated CPUs should really leave the root task group,
	 * whether they are isolcpus or were isolated via cpusets, lest
	 * the timer run on a CPU which does not service all runqueues,
	 * potentially leaving other CPUs indefinitely throttled.  If
	 * isolation is really required, the user will turn the throttle
	 * off to kill the perturbations it causes anyway.  Meanwhile,
	 * this maintains functionality for boot and/or troubleshooting.
	 */
	if (rt_b == &root_task_group.rt_bandwidth)
		span = cpu_online_mask;
#endif
804
	for_each_cpu(i, span) {
805 806 807 808
		int enqueue = 0;
		struct rt_rq *rt_rq = sched_rt_period_rt_rq(rt_b, i);
		struct rq *rq = rq_of_rt_rq(rt_rq);

809
		raw_spin_lock(&rq->lock);
810 811 812
		if (rt_rq->rt_time) {
			u64 runtime;

813
			raw_spin_lock(&rt_rq->rt_runtime_lock);
814 815 816 817 818 819 820
			if (rt_rq->rt_throttled)
				balance_runtime(rt_rq);
			runtime = rt_rq->rt_runtime;
			rt_rq->rt_time -= min(rt_rq->rt_time, overrun*runtime);
			if (rt_rq->rt_throttled && rt_rq->rt_time < runtime) {
				rt_rq->rt_throttled = 0;
				enqueue = 1;
821 822 823 824 825 826 827

				/*
				 * Force a clock update if the CPU was idle,
				 * lest wakeup -> unthrottle time accumulate.
				 */
				if (rt_rq->rt_nr_running && rq->curr == rq->idle)
					rq->skip_clock_update = -1;
828 829 830
			}
			if (rt_rq->rt_time || rt_rq->rt_nr_running)
				idle = 0;
831
			raw_spin_unlock(&rt_rq->rt_runtime_lock);
832
		} else if (rt_rq->rt_nr_running) {
833
			idle = 0;
834 835 836
			if (!rt_rq_throttled(rt_rq))
				enqueue = 1;
		}
837 838
		if (rt_rq->rt_throttled)
			throttled = 1;
839 840 841

		if (enqueue)
			sched_rt_rq_enqueue(rt_rq);
842
		raw_spin_unlock(&rq->lock);
843 844
	}

845 846 847
	if (!throttled && (!rt_bandwidth_enabled() || rt_b->rt_runtime == RUNTIME_INF))
		return 1;

848 849
	return idle;
}
P
Peter Zijlstra 已提交
850

P
Peter Zijlstra 已提交
851 852
static inline int rt_se_prio(struct sched_rt_entity *rt_se)
{
853
#ifdef CONFIG_RT_GROUP_SCHED
P
Peter Zijlstra 已提交
854 855 856
	struct rt_rq *rt_rq = group_rt_rq(rt_se);

	if (rt_rq)
857
		return rt_rq->highest_prio.curr;
P
Peter Zijlstra 已提交
858 859 860 861 862
#endif

	return rt_task_of(rt_se)->prio;
}

P
Peter Zijlstra 已提交
863
static int sched_rt_runtime_exceeded(struct rt_rq *rt_rq)
P
Peter Zijlstra 已提交
864
{
P
Peter Zijlstra 已提交
865
	u64 runtime = sched_rt_runtime(rt_rq);
P
Peter Zijlstra 已提交
866 867

	if (rt_rq->rt_throttled)
P
Peter Zijlstra 已提交
868
		return rt_rq_throttled(rt_rq);
P
Peter Zijlstra 已提交
869

870
	if (runtime >= sched_rt_period(rt_rq))
P
Peter Zijlstra 已提交
871 872
		return 0;

873 874 875 876
	balance_runtime(rt_rq);
	runtime = sched_rt_runtime(rt_rq);
	if (runtime == RUNTIME_INF)
		return 0;
P
Peter Zijlstra 已提交
877

P
Peter Zijlstra 已提交
878
	if (rt_rq->rt_time > runtime) {
879 880 881 882 883 884 885
		struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);

		/*
		 * Don't actually throttle groups that have no runtime assigned
		 * but accrue some time due to boosting.
		 */
		if (likely(rt_b->rt_runtime)) {
886 887
			static bool once = false;

888
			rt_rq->rt_throttled = 1;
889 890 891 892 893

			if (!once) {
				once = true;
				printk_sched("sched: RT throttling activated\n");
			}
894 895 896 897 898 899 900 901 902
		} else {
			/*
			 * In case we did anyway, make it go away,
			 * replenishment is a joke, since it will replenish us
			 * with exactly 0 ns.
			 */
			rt_rq->rt_time = 0;
		}

P
Peter Zijlstra 已提交
903
		if (rt_rq_throttled(rt_rq)) {
P
Peter Zijlstra 已提交
904
			sched_rt_rq_dequeue(rt_rq);
P
Peter Zijlstra 已提交
905 906
			return 1;
		}
P
Peter Zijlstra 已提交
907 908 909 910 911
	}

	return 0;
}

I
Ingo Molnar 已提交
912 913 914 915
/*
 * Update the current task's runtime statistics. Skip current tasks that
 * are not in our scheduling class.
 */
A
Alexey Dobriyan 已提交
916
static void update_curr_rt(struct rq *rq)
I
Ingo Molnar 已提交
917 918
{
	struct task_struct *curr = rq->curr;
P
Peter Zijlstra 已提交
919 920
	struct sched_rt_entity *rt_se = &curr->rt;
	struct rt_rq *rt_rq = rt_rq_of_se(rt_se);
I
Ingo Molnar 已提交
921 922
	u64 delta_exec;

P
Peter Zijlstra 已提交
923
	if (curr->sched_class != &rt_sched_class)
I
Ingo Molnar 已提交
924 925
		return;

926
	delta_exec = rq->clock_task - curr->se.exec_start;
I
Ingo Molnar 已提交
927 928
	if (unlikely((s64)delta_exec < 0))
		delta_exec = 0;
I
Ingo Molnar 已提交
929

930 931
	schedstat_set(curr->se.statistics.exec_max,
		      max(curr->se.statistics.exec_max, delta_exec));
I
Ingo Molnar 已提交
932 933

	curr->se.sum_exec_runtime += delta_exec;
934 935
	account_group_exec_runtime(curr, delta_exec);

936
	curr->se.exec_start = rq->clock_task;
937
	cpuacct_charge(curr, delta_exec);
P
Peter Zijlstra 已提交
938

939 940
	sched_rt_avg_update(rq, delta_exec);

941 942 943
	if (!rt_bandwidth_enabled())
		return;

D
Dhaval Giani 已提交
944 945 946
	for_each_sched_rt_entity(rt_se) {
		rt_rq = rt_rq_of_se(rt_se);

947
		if (sched_rt_runtime(rt_rq) != RUNTIME_INF) {
948
			raw_spin_lock(&rt_rq->rt_runtime_lock);
949 950 951
			rt_rq->rt_time += delta_exec;
			if (sched_rt_runtime_exceeded(rt_rq))
				resched_task(curr);
952
			raw_spin_unlock(&rt_rq->rt_runtime_lock);
953
		}
D
Dhaval Giani 已提交
954
	}
I
Ingo Molnar 已提交
955 956
}

957
#if defined CONFIG_SMP
958

959 960
static void
inc_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio)
961
{
G
Gregory Haskins 已提交
962
	struct rq *rq = rq_of_rt_rq(rt_rq);
963

964 965
	if (rq->online && prio < prev_prio)
		cpupri_set(&rq->rd->cpupri, rq->cpu, prio);
966
}
967

968 969 970 971
static void
dec_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio)
{
	struct rq *rq = rq_of_rt_rq(rt_rq);
972

973 974
	if (rq->online && rt_rq->highest_prio.curr != prev_prio)
		cpupri_set(&rq->rd->cpupri, rq->cpu, rt_rq->highest_prio.curr);
975 976
}

977 978
#else /* CONFIG_SMP */

P
Peter Zijlstra 已提交
979
static inline
980 981 982 983 984
void inc_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio) {}
static inline
void dec_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio) {}

#endif /* CONFIG_SMP */
985

986
#if defined CONFIG_SMP || defined CONFIG_RT_GROUP_SCHED
987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002
static void
inc_rt_prio(struct rt_rq *rt_rq, int prio)
{
	int prev_prio = rt_rq->highest_prio.curr;

	if (prio < prev_prio)
		rt_rq->highest_prio.curr = prio;

	inc_rt_prio_smp(rt_rq, prio, prev_prio);
}

static void
dec_rt_prio(struct rt_rq *rt_rq, int prio)
{
	int prev_prio = rt_rq->highest_prio.curr;

P
Peter Zijlstra 已提交
1003
	if (rt_rq->rt_nr_running) {
1004

1005
		WARN_ON(prio < prev_prio);
1006

1007
		/*
1008 1009
		 * This may have been our highest task, and therefore
		 * we may have some recomputation to do
1010
		 */
1011
		if (prio == prev_prio) {
1012 1013 1014
			struct rt_prio_array *array = &rt_rq->active;

			rt_rq->highest_prio.curr =
1015
				sched_find_first_bit(array->bitmap);
1016 1017
		}

1018
	} else
1019
		rt_rq->highest_prio.curr = MAX_RT_PRIO;
1020

1021 1022
	dec_rt_prio_smp(rt_rq, prio, prev_prio);
}
1023

1024 1025 1026 1027 1028 1029
#else

static inline void inc_rt_prio(struct rt_rq *rt_rq, int prio) {}
static inline void dec_rt_prio(struct rt_rq *rt_rq, int prio) {}

#endif /* CONFIG_SMP || CONFIG_RT_GROUP_SCHED */
1030

1031
#ifdef CONFIG_RT_GROUP_SCHED
1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045

static void
inc_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
{
	if (rt_se_boosted(rt_se))
		rt_rq->rt_nr_boosted++;

	if (rt_rq->tg)
		start_rt_bandwidth(&rt_rq->tg->rt_bandwidth);
}

static void
dec_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
{
P
Peter Zijlstra 已提交
1046 1047 1048 1049
	if (rt_se_boosted(rt_se))
		rt_rq->rt_nr_boosted--;

	WARN_ON(!rt_rq->rt_nr_running && rt_rq->rt_nr_boosted);
1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087
}

#else /* CONFIG_RT_GROUP_SCHED */

static void
inc_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
{
	start_rt_bandwidth(&def_rt_bandwidth);
}

static inline
void dec_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq) {}

#endif /* CONFIG_RT_GROUP_SCHED */

static inline
void inc_rt_tasks(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
{
	int prio = rt_se_prio(rt_se);

	WARN_ON(!rt_prio(prio));
	rt_rq->rt_nr_running++;

	inc_rt_prio(rt_rq, prio);
	inc_rt_migration(rt_se, rt_rq);
	inc_rt_group(rt_se, rt_rq);
}

static inline
void dec_rt_tasks(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
{
	WARN_ON(!rt_prio(rt_se_prio(rt_se)));
	WARN_ON(!rt_rq->rt_nr_running);
	rt_rq->rt_nr_running--;

	dec_rt_prio(rt_rq, rt_se_prio(rt_se));
	dec_rt_migration(rt_se, rt_rq);
	dec_rt_group(rt_se, rt_rq);
1088 1089
}

1090
static void __enqueue_rt_entity(struct sched_rt_entity *rt_se, bool head)
I
Ingo Molnar 已提交
1091
{
P
Peter Zijlstra 已提交
1092 1093 1094
	struct rt_rq *rt_rq = rt_rq_of_se(rt_se);
	struct rt_prio_array *array = &rt_rq->active;
	struct rt_rq *group_rq = group_rt_rq(rt_se);
1095
	struct list_head *queue = array->queue + rt_se_prio(rt_se);
I
Ingo Molnar 已提交
1096

1097 1098 1099 1100 1101 1102 1103
	/*
	 * Don't enqueue the group if its throttled, or when empty.
	 * The latter is a consequence of the former when a child group
	 * get throttled and the current group doesn't have any other
	 * active members.
	 */
	if (group_rq && (rt_rq_throttled(group_rq) || !group_rq->rt_nr_running))
P
Peter Zijlstra 已提交
1104
		return;
1105

1106 1107 1108
	if (!rt_rq->rt_nr_running)
		list_add_leaf_rt_rq(rt_rq);

1109 1110 1111 1112
	if (head)
		list_add(&rt_se->run_list, queue);
	else
		list_add_tail(&rt_se->run_list, queue);
P
Peter Zijlstra 已提交
1113
	__set_bit(rt_se_prio(rt_se), array->bitmap);
1114

P
Peter Zijlstra 已提交
1115 1116 1117
	inc_rt_tasks(rt_se, rt_rq);
}

1118
static void __dequeue_rt_entity(struct sched_rt_entity *rt_se)
P
Peter Zijlstra 已提交
1119 1120 1121 1122 1123 1124 1125 1126 1127
{
	struct rt_rq *rt_rq = rt_rq_of_se(rt_se);
	struct rt_prio_array *array = &rt_rq->active;

	list_del_init(&rt_se->run_list);
	if (list_empty(array->queue + rt_se_prio(rt_se)))
		__clear_bit(rt_se_prio(rt_se), array->bitmap);

	dec_rt_tasks(rt_se, rt_rq);
1128 1129
	if (!rt_rq->rt_nr_running)
		list_del_leaf_rt_rq(rt_rq);
P
Peter Zijlstra 已提交
1130 1131 1132 1133 1134 1135
}

/*
 * Because the prio of an upper entry depends on the lower
 * entries, we must remove entries top - down.
 */
1136
static void dequeue_rt_stack(struct sched_rt_entity *rt_se)
P
Peter Zijlstra 已提交
1137
{
1138
	struct sched_rt_entity *back = NULL;
P
Peter Zijlstra 已提交
1139

1140 1141 1142 1143 1144 1145 1146
	for_each_sched_rt_entity(rt_se) {
		rt_se->back = back;
		back = rt_se;
	}

	for (rt_se = back; rt_se; rt_se = rt_se->back) {
		if (on_rt_rq(rt_se))
1147 1148 1149 1150
			__dequeue_rt_entity(rt_se);
	}
}

1151
static void enqueue_rt_entity(struct sched_rt_entity *rt_se, bool head)
1152 1153 1154
{
	dequeue_rt_stack(rt_se);
	for_each_sched_rt_entity(rt_se)
1155
		__enqueue_rt_entity(rt_se, head);
1156 1157 1158 1159 1160 1161 1162 1163 1164 1165
}

static void dequeue_rt_entity(struct sched_rt_entity *rt_se)
{
	dequeue_rt_stack(rt_se);

	for_each_sched_rt_entity(rt_se) {
		struct rt_rq *rt_rq = group_rt_rq(rt_se);

		if (rt_rq && rt_rq->rt_nr_running)
1166
			__enqueue_rt_entity(rt_se, false);
1167
	}
I
Ingo Molnar 已提交
1168 1169 1170 1171 1172
}

/*
 * Adding/removing a task to/from a priority array:
 */
1173
static void
1174
enqueue_task_rt(struct rq *rq, struct task_struct *p, int flags)
P
Peter Zijlstra 已提交
1175 1176 1177
{
	struct sched_rt_entity *rt_se = &p->rt;

1178
	if (flags & ENQUEUE_WAKEUP)
P
Peter Zijlstra 已提交
1179 1180
		rt_se->timeout = 0;

1181
	enqueue_rt_entity(rt_se, flags & ENQUEUE_HEAD);
1182

1183
	if (!task_current(rq, p) && p->nr_cpus_allowed > 1)
1184
		enqueue_pushable_task(rq, p);
1185 1186

	inc_nr_running(rq);
P
Peter Zijlstra 已提交
1187 1188
}

1189
static void dequeue_task_rt(struct rq *rq, struct task_struct *p, int flags)
I
Ingo Molnar 已提交
1190
{
P
Peter Zijlstra 已提交
1191
	struct sched_rt_entity *rt_se = &p->rt;
I
Ingo Molnar 已提交
1192

1193
	update_curr_rt(rq);
1194
	dequeue_rt_entity(rt_se);
1195

1196
	dequeue_pushable_task(rq, p);
1197 1198

	dec_nr_running(rq);
I
Ingo Molnar 已提交
1199 1200 1201
}

/*
1202 1203
 * Put task to the head or the end of the run list without the overhead of
 * dequeue followed by enqueue.
I
Ingo Molnar 已提交
1204
 */
1205 1206
static void
requeue_rt_entity(struct rt_rq *rt_rq, struct sched_rt_entity *rt_se, int head)
P
Peter Zijlstra 已提交
1207
{
1208
	if (on_rt_rq(rt_se)) {
1209 1210 1211 1212 1213 1214 1215
		struct rt_prio_array *array = &rt_rq->active;
		struct list_head *queue = array->queue + rt_se_prio(rt_se);

		if (head)
			list_move(&rt_se->run_list, queue);
		else
			list_move_tail(&rt_se->run_list, queue);
1216
	}
P
Peter Zijlstra 已提交
1217 1218
}

1219
static void requeue_task_rt(struct rq *rq, struct task_struct *p, int head)
I
Ingo Molnar 已提交
1220
{
P
Peter Zijlstra 已提交
1221 1222
	struct sched_rt_entity *rt_se = &p->rt;
	struct rt_rq *rt_rq;
I
Ingo Molnar 已提交
1223

P
Peter Zijlstra 已提交
1224 1225
	for_each_sched_rt_entity(rt_se) {
		rt_rq = rt_rq_of_se(rt_se);
1226
		requeue_rt_entity(rt_rq, rt_se, head);
P
Peter Zijlstra 已提交
1227
	}
I
Ingo Molnar 已提交
1228 1229
}

P
Peter Zijlstra 已提交
1230
static void yield_task_rt(struct rq *rq)
I
Ingo Molnar 已提交
1231
{
1232
	requeue_task_rt(rq, rq->curr, 0);
I
Ingo Molnar 已提交
1233 1234
}

1235
#ifdef CONFIG_SMP
1236 1237
static int find_lowest_rq(struct task_struct *task);

1238
static int
1239
select_task_rq_rt(struct task_struct *p, int sd_flag, int flags)
1240
{
1241 1242 1243 1244 1245
	struct task_struct *curr;
	struct rq *rq;
	int cpu;

	cpu = task_cpu(p);
1246

1247
	if (p->nr_cpus_allowed == 1)
1248 1249
		goto out;

1250 1251 1252 1253
	/* For anything but wake ups, just return the task_cpu */
	if (sd_flag != SD_BALANCE_WAKE && sd_flag != SD_BALANCE_FORK)
		goto out;

1254 1255 1256 1257 1258
	rq = cpu_rq(cpu);

	rcu_read_lock();
	curr = ACCESS_ONCE(rq->curr); /* unlocked access */

1259
	/*
1260
	 * If the current task on @p's runqueue is an RT task, then
1261 1262 1263 1264
	 * try to see if we can wake this RT task up on another
	 * runqueue. Otherwise simply start this RT task
	 * on its current runqueue.
	 *
1265 1266 1267 1268 1269 1270 1271 1272 1273
	 * We want to avoid overloading runqueues. If the woken
	 * task is a higher priority, then it will stay on this CPU
	 * and the lower prio task should be moved to another CPU.
	 * Even though this will probably make the lower prio task
	 * lose its cache, we do not want to bounce a higher task
	 * around just because it gave up its CPU, perhaps for a
	 * lock?
	 *
	 * For equal prio tasks, we just let the scheduler sort it out.
1274 1275 1276 1277 1278 1279
	 *
	 * Otherwise, just let it ride on the affined RQ and the
	 * post-schedule router will push the preempted task away
	 *
	 * This test is optimistic, if we get it wrong the load-balancer
	 * will have to sort it out.
1280
	 */
1281
	if (curr && unlikely(rt_task(curr)) &&
1282
	    (curr->nr_cpus_allowed < 2 ||
1283
	     curr->prio <= p->prio) &&
1284
	    (p->nr_cpus_allowed > 1)) {
1285
		int target = find_lowest_rq(p);
1286

1287 1288
		if (target != -1)
			cpu = target;
1289
	}
1290
	rcu_read_unlock();
1291

1292
out:
1293
	return cpu;
1294
}
1295 1296 1297

static void check_preempt_equal_prio(struct rq *rq, struct task_struct *p)
{
1298
	if (rq->curr->nr_cpus_allowed == 1)
1299 1300
		return;

1301
	if (p->nr_cpus_allowed != 1
1302 1303
	    && cpupri_find(&rq->rd->cpupri, p, NULL))
		return;
1304

1305 1306
	if (!cpupri_find(&rq->rd->cpupri, rq->curr, NULL))
		return;
1307 1308 1309 1310 1311 1312 1313 1314 1315 1316

	/*
	 * There appears to be other cpus that can accept
	 * current and none to run 'p', so lets reschedule
	 * to try and push current away:
	 */
	requeue_task_rt(rq, p, 1);
	resched_task(rq->curr);
}

1317 1318
#endif /* CONFIG_SMP */

I
Ingo Molnar 已提交
1319 1320 1321
/*
 * Preempt the current task with a newly woken task if needed:
 */
P
Peter Zijlstra 已提交
1322
static void check_preempt_curr_rt(struct rq *rq, struct task_struct *p, int flags)
I
Ingo Molnar 已提交
1323
{
1324
	if (p->prio < rq->curr->prio) {
I
Ingo Molnar 已提交
1325
		resched_task(rq->curr);
1326 1327 1328 1329 1330 1331 1332 1333 1334 1335 1336 1337 1338 1339 1340 1341
		return;
	}

#ifdef CONFIG_SMP
	/*
	 * If:
	 *
	 * - the newly woken task is of equal priority to the current task
	 * - the newly woken task is non-migratable while current is migratable
	 * - current will be preempted on the next reschedule
	 *
	 * we should check to see if current can readily move to a different
	 * cpu.  If so, we will reschedule to allow the push logic to try
	 * to move current somewhere else, making room for our non-migratable
	 * task.
	 */
1342
	if (p->prio == rq->curr->prio && !test_tsk_need_resched(rq->curr))
1343
		check_preempt_equal_prio(rq, p);
1344
#endif
I
Ingo Molnar 已提交
1345 1346
}

P
Peter Zijlstra 已提交
1347 1348
static struct sched_rt_entity *pick_next_rt_entity(struct rq *rq,
						   struct rt_rq *rt_rq)
I
Ingo Molnar 已提交
1349
{
P
Peter Zijlstra 已提交
1350 1351
	struct rt_prio_array *array = &rt_rq->active;
	struct sched_rt_entity *next = NULL;
I
Ingo Molnar 已提交
1352 1353 1354 1355
	struct list_head *queue;
	int idx;

	idx = sched_find_first_bit(array->bitmap);
P
Peter Zijlstra 已提交
1356
	BUG_ON(idx >= MAX_RT_PRIO);
I
Ingo Molnar 已提交
1357 1358

	queue = array->queue + idx;
P
Peter Zijlstra 已提交
1359
	next = list_entry(queue->next, struct sched_rt_entity, run_list);
1360

P
Peter Zijlstra 已提交
1361 1362
	return next;
}
I
Ingo Molnar 已提交
1363

1364
static struct task_struct *_pick_next_task_rt(struct rq *rq)
P
Peter Zijlstra 已提交
1365 1366 1367 1368
{
	struct sched_rt_entity *rt_se;
	struct task_struct *p;
	struct rt_rq *rt_rq;
I
Ingo Molnar 已提交
1369

P
Peter Zijlstra 已提交
1370 1371
	rt_rq = &rq->rt;

1372
	if (!rt_rq->rt_nr_running)
P
Peter Zijlstra 已提交
1373 1374
		return NULL;

P
Peter Zijlstra 已提交
1375
	if (rt_rq_throttled(rt_rq))
P
Peter Zijlstra 已提交
1376 1377 1378 1379
		return NULL;

	do {
		rt_se = pick_next_rt_entity(rq, rt_rq);
1380
		BUG_ON(!rt_se);
P
Peter Zijlstra 已提交
1381 1382 1383 1384
		rt_rq = group_rt_rq(rt_se);
	} while (rt_rq);

	p = rt_task_of(rt_se);
1385
	p->se.exec_start = rq->clock_task;
1386 1387 1388 1389 1390 1391 1392 1393 1394 1395 1396 1397

	return p;
}

static struct task_struct *pick_next_task_rt(struct rq *rq)
{
	struct task_struct *p = _pick_next_task_rt(rq);

	/* The running task is never eligible for pushing */
	if (p)
		dequeue_pushable_task(rq, p);

1398
#ifdef CONFIG_SMP
1399 1400 1401 1402 1403
	/*
	 * 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);
1404
#endif
1405

P
Peter Zijlstra 已提交
1406
	return p;
I
Ingo Molnar 已提交
1407 1408
}

1409
static void put_prev_task_rt(struct rq *rq, struct task_struct *p)
I
Ingo Molnar 已提交
1410
{
1411
	update_curr_rt(rq);
1412 1413 1414 1415 1416

	/*
	 * The previous task needs to be made eligible for pushing
	 * if it is still active
	 */
1417
	if (on_rt_rq(&p->rt) && p->nr_cpus_allowed > 1)
1418
		enqueue_pushable_task(rq, p);
I
Ingo Molnar 已提交
1419 1420
}

1421
#ifdef CONFIG_SMP
P
Peter Zijlstra 已提交
1422

S
Steven Rostedt 已提交
1423 1424 1425
/* Only try algorithms three times */
#define RT_MAX_TRIES 3

1426 1427 1428
static int pick_rt_task(struct rq *rq, struct task_struct *p, int cpu)
{
	if (!task_running(rq, p) &&
1429
	    (cpu < 0 || cpumask_test_cpu(cpu, tsk_cpus_allowed(p))) &&
1430
	    (p->nr_cpus_allowed > 1))
1431 1432 1433 1434
		return 1;
	return 0;
}

S
Steven Rostedt 已提交
1435
/* Return the second highest RT task, NULL otherwise */
1436
static struct task_struct *pick_next_highest_task_rt(struct rq *rq, int cpu)
S
Steven Rostedt 已提交
1437
{
P
Peter Zijlstra 已提交
1438 1439 1440 1441
	struct task_struct *next = NULL;
	struct sched_rt_entity *rt_se;
	struct rt_prio_array *array;
	struct rt_rq *rt_rq;
S
Steven Rostedt 已提交
1442 1443
	int idx;

P
Peter Zijlstra 已提交
1444 1445 1446
	for_each_leaf_rt_rq(rt_rq, rq) {
		array = &rt_rq->active;
		idx = sched_find_first_bit(array->bitmap);
P
Peter Zijlstra 已提交
1447
next_idx:
P
Peter Zijlstra 已提交
1448 1449
		if (idx >= MAX_RT_PRIO)
			continue;
1450
		if (next && next->prio <= idx)
P
Peter Zijlstra 已提交
1451 1452
			continue;
		list_for_each_entry(rt_se, array->queue + idx, run_list) {
1453 1454 1455 1456 1457 1458
			struct task_struct *p;

			if (!rt_entity_is_task(rt_se))
				continue;

			p = rt_task_of(rt_se);
P
Peter Zijlstra 已提交
1459 1460 1461 1462 1463 1464 1465 1466 1467
			if (pick_rt_task(rq, p, cpu)) {
				next = p;
				break;
			}
		}
		if (!next) {
			idx = find_next_bit(array->bitmap, MAX_RT_PRIO, idx+1);
			goto next_idx;
		}
1468 1469
	}

S
Steven Rostedt 已提交
1470 1471 1472
	return next;
}

1473
static DEFINE_PER_CPU(cpumask_var_t, local_cpu_mask);
S
Steven Rostedt 已提交
1474

G
Gregory Haskins 已提交
1475 1476 1477
static int find_lowest_rq(struct task_struct *task)
{
	struct sched_domain *sd;
1478
	struct cpumask *lowest_mask = __get_cpu_var(local_cpu_mask);
G
Gregory Haskins 已提交
1479 1480
	int this_cpu = smp_processor_id();
	int cpu      = task_cpu(task);
G
Gregory Haskins 已提交
1481

1482 1483 1484 1485
	/* Make sure the mask is initialized first */
	if (unlikely(!lowest_mask))
		return -1;

1486
	if (task->nr_cpus_allowed == 1)
1487
		return -1; /* No other targets possible */
G
Gregory Haskins 已提交
1488

1489 1490
	if (!cpupri_find(&task_rq(task)->rd->cpupri, task, lowest_mask))
		return -1; /* No targets found */
G
Gregory Haskins 已提交
1491 1492 1493 1494 1495 1496 1497 1498 1499

	/*
	 * At this point we have built a mask of cpus representing the
	 * lowest priority tasks in the system.  Now we want to elect
	 * the best one based on our affinity and topology.
	 *
	 * We prioritize the last cpu that the task executed on since
	 * it is most likely cache-hot in that location.
	 */
1500
	if (cpumask_test_cpu(cpu, lowest_mask))
G
Gregory Haskins 已提交
1501 1502 1503 1504 1505 1506
		return cpu;

	/*
	 * Otherwise, we consult the sched_domains span maps to figure
	 * out which cpu is logically closest to our hot cache data.
	 */
R
Rusty Russell 已提交
1507 1508
	if (!cpumask_test_cpu(this_cpu, lowest_mask))
		this_cpu = -1; /* Skip this_cpu opt if not among lowest */
G
Gregory Haskins 已提交
1509

1510
	rcu_read_lock();
R
Rusty Russell 已提交
1511 1512 1513
	for_each_domain(cpu, sd) {
		if (sd->flags & SD_WAKE_AFFINE) {
			int best_cpu;
G
Gregory Haskins 已提交
1514

R
Rusty Russell 已提交
1515 1516 1517 1518 1519
			/*
			 * "this_cpu" is cheaper to preempt than a
			 * remote processor.
			 */
			if (this_cpu != -1 &&
1520 1521
			    cpumask_test_cpu(this_cpu, sched_domain_span(sd))) {
				rcu_read_unlock();
R
Rusty Russell 已提交
1522
				return this_cpu;
1523
			}
R
Rusty Russell 已提交
1524 1525 1526

			best_cpu = cpumask_first_and(lowest_mask,
						     sched_domain_span(sd));
1527 1528
			if (best_cpu < nr_cpu_ids) {
				rcu_read_unlock();
R
Rusty Russell 已提交
1529
				return best_cpu;
1530
			}
G
Gregory Haskins 已提交
1531 1532
		}
	}
1533
	rcu_read_unlock();
G
Gregory Haskins 已提交
1534 1535 1536 1537 1538 1539

	/*
	 * And finally, if there were no matches within the domains
	 * just give the caller *something* to work with from the compatible
	 * locations.
	 */
R
Rusty Russell 已提交
1540 1541 1542 1543 1544 1545 1546
	if (this_cpu != -1)
		return this_cpu;

	cpu = cpumask_any(lowest_mask);
	if (cpu < nr_cpu_ids)
		return cpu;
	return -1;
1547 1548 1549
}

/* Will lock the rq it finds */
1550
static struct rq *find_lock_lowest_rq(struct task_struct *task, struct rq *rq)
1551 1552 1553
{
	struct rq *lowest_rq = NULL;
	int tries;
1554
	int cpu;
S
Steven Rostedt 已提交
1555

1556 1557 1558
	for (tries = 0; tries < RT_MAX_TRIES; tries++) {
		cpu = find_lowest_rq(task);

1559
		if ((cpu == -1) || (cpu == rq->cpu))
S
Steven Rostedt 已提交
1560 1561
			break;

1562 1563
		lowest_rq = cpu_rq(cpu);

S
Steven Rostedt 已提交
1564
		/* if the prio of this runqueue changed, try again */
1565
		if (double_lock_balance(rq, lowest_rq)) {
S
Steven Rostedt 已提交
1566 1567 1568 1569 1570 1571
			/*
			 * We had to unlock the run queue. In
			 * the mean time, task could have
			 * migrated already or had its affinity changed.
			 * Also make sure that it wasn't scheduled on its rq.
			 */
1572
			if (unlikely(task_rq(task) != rq ||
1573
				     !cpumask_test_cpu(lowest_rq->cpu,
1574
						       tsk_cpus_allowed(task)) ||
1575
				     task_running(rq, task) ||
P
Peter Zijlstra 已提交
1576
				     !task->on_rq)) {
1577

1578
				double_unlock_balance(rq, lowest_rq);
S
Steven Rostedt 已提交
1579 1580 1581 1582 1583 1584
				lowest_rq = NULL;
				break;
			}
		}

		/* If this rq is still suitable use it. */
1585
		if (lowest_rq->rt.highest_prio.curr > task->prio)
S
Steven Rostedt 已提交
1586 1587 1588
			break;

		/* try again */
1589
		double_unlock_balance(rq, lowest_rq);
S
Steven Rostedt 已提交
1590 1591 1592 1593 1594 1595
		lowest_rq = NULL;
	}

	return lowest_rq;
}

1596 1597 1598 1599 1600 1601 1602 1603 1604 1605 1606 1607
static struct task_struct *pick_next_pushable_task(struct rq *rq)
{
	struct task_struct *p;

	if (!has_pushable_tasks(rq))
		return NULL;

	p = plist_first_entry(&rq->rt.pushable_tasks,
			      struct task_struct, pushable_tasks);

	BUG_ON(rq->cpu != task_cpu(p));
	BUG_ON(task_current(rq, p));
1608
	BUG_ON(p->nr_cpus_allowed <= 1);
1609

P
Peter Zijlstra 已提交
1610
	BUG_ON(!p->on_rq);
1611 1612 1613 1614 1615
	BUG_ON(!rt_task(p));

	return p;
}

S
Steven Rostedt 已提交
1616 1617 1618 1619 1620
/*
 * If the current CPU has more than one RT task, see if the non
 * running task can migrate over to a CPU that is running a task
 * of lesser priority.
 */
1621
static int push_rt_task(struct rq *rq)
S
Steven Rostedt 已提交
1622 1623 1624
{
	struct task_struct *next_task;
	struct rq *lowest_rq;
1625
	int ret = 0;
S
Steven Rostedt 已提交
1626

G
Gregory Haskins 已提交
1627 1628 1629
	if (!rq->rt.overloaded)
		return 0;

1630
	next_task = pick_next_pushable_task(rq);
S
Steven Rostedt 已提交
1631 1632 1633
	if (!next_task)
		return 0;

1634 1635 1636 1637 1638
#ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
       if (unlikely(task_running(rq, next_task)))
               return 0;
#endif

P
Peter Zijlstra 已提交
1639
retry:
1640
	if (unlikely(next_task == rq->curr)) {
1641
		WARN_ON(1);
S
Steven Rostedt 已提交
1642
		return 0;
1643
	}
S
Steven Rostedt 已提交
1644 1645 1646 1647 1648 1649

	/*
	 * It's possible that the next_task slipped in of
	 * higher priority than current. If that's the case
	 * just reschedule current.
	 */
1650 1651
	if (unlikely(next_task->prio < rq->curr->prio)) {
		resched_task(rq->curr);
S
Steven Rostedt 已提交
1652 1653 1654
		return 0;
	}

1655
	/* We might release rq lock */
S
Steven Rostedt 已提交
1656 1657 1658
	get_task_struct(next_task);

	/* find_lock_lowest_rq locks the rq if found */
1659
	lowest_rq = find_lock_lowest_rq(next_task, rq);
S
Steven Rostedt 已提交
1660 1661 1662
	if (!lowest_rq) {
		struct task_struct *task;
		/*
1663
		 * find_lock_lowest_rq releases rq->lock
1664 1665 1666 1667 1668
		 * so it is possible that next_task has migrated.
		 *
		 * We need to make sure that the task is still on the same
		 * run-queue and is also still the next task eligible for
		 * pushing.
S
Steven Rostedt 已提交
1669
		 */
1670
		task = pick_next_pushable_task(rq);
1671 1672
		if (task_cpu(next_task) == rq->cpu && task == next_task) {
			/*
1673 1674 1675 1676
			 * The task hasn't migrated, and is still the next
			 * eligible task, but we failed to find a run-queue
			 * to push it to.  Do not retry in this case, since
			 * other cpus will pull from us when ready.
1677 1678
			 */
			goto out;
S
Steven Rostedt 已提交
1679
		}
1680

1681 1682 1683 1684
		if (!task)
			/* No more tasks, just exit */
			goto out;

1685
		/*
1686
		 * Something has shifted, try again.
1687
		 */
1688 1689 1690
		put_task_struct(next_task);
		next_task = task;
		goto retry;
S
Steven Rostedt 已提交
1691 1692
	}

1693
	deactivate_task(rq, next_task, 0);
S
Steven Rostedt 已提交
1694 1695
	set_task_cpu(next_task, lowest_rq->cpu);
	activate_task(lowest_rq, next_task, 0);
1696
	ret = 1;
S
Steven Rostedt 已提交
1697 1698 1699

	resched_task(lowest_rq->curr);

1700
	double_unlock_balance(rq, lowest_rq);
S
Steven Rostedt 已提交
1701 1702 1703 1704

out:
	put_task_struct(next_task);

1705
	return ret;
S
Steven Rostedt 已提交
1706 1707 1708 1709 1710 1711 1712 1713 1714
}

static void push_rt_tasks(struct rq *rq)
{
	/* push_rt_task will return true if it moved an RT */
	while (push_rt_task(rq))
		;
}

1715 1716
static int pull_rt_task(struct rq *this_rq)
{
I
Ingo Molnar 已提交
1717
	int this_cpu = this_rq->cpu, ret = 0, cpu;
1718
	struct task_struct *p;
1719 1720
	struct rq *src_rq;

1721
	if (likely(!rt_overloaded(this_rq)))
1722 1723
		return 0;

1724
	for_each_cpu(cpu, this_rq->rd->rto_mask) {
1725 1726 1727 1728
		if (this_cpu == cpu)
			continue;

		src_rq = cpu_rq(cpu);
1729 1730 1731 1732 1733 1734 1735 1736 1737 1738 1739 1740

		/*
		 * Don't bother taking the src_rq->lock if the next highest
		 * task is known to be lower-priority than our current task.
		 * This may look racy, but if this value is about to go
		 * logically higher, the src_rq will push this task away.
		 * And if its going logically lower, we do not care
		 */
		if (src_rq->rt.highest_prio.next >=
		    this_rq->rt.highest_prio.curr)
			continue;

1741 1742 1743
		/*
		 * We can potentially drop this_rq's lock in
		 * double_lock_balance, and another CPU could
1744
		 * alter this_rq
1745
		 */
1746
		double_lock_balance(this_rq, src_rq);
1747 1748 1749 1750

		/*
		 * Are there still pullable RT tasks?
		 */
M
Mike Galbraith 已提交
1751 1752
		if (src_rq->rt.rt_nr_running <= 1)
			goto skip;
1753 1754 1755 1756 1757 1758 1759

		p = pick_next_highest_task_rt(src_rq, this_cpu);

		/*
		 * Do we have an RT task that preempts
		 * the to-be-scheduled task?
		 */
1760
		if (p && (p->prio < this_rq->rt.highest_prio.curr)) {
1761
			WARN_ON(p == src_rq->curr);
P
Peter Zijlstra 已提交
1762
			WARN_ON(!p->on_rq);
1763 1764 1765 1766 1767 1768 1769

			/*
			 * There's a chance that p is higher in priority
			 * than what's currently running on its cpu.
			 * This is just that p is wakeing up and hasn't
			 * had a chance to schedule. We only pull
			 * p if it is lower in priority than the
1770
			 * current task on the run queue
1771
			 */
1772
			if (p->prio < src_rq->curr->prio)
M
Mike Galbraith 已提交
1773
				goto skip;
1774 1775 1776 1777 1778 1779 1780 1781 1782

			ret = 1;

			deactivate_task(src_rq, p, 0);
			set_task_cpu(p, this_cpu);
			activate_task(this_rq, p, 0);
			/*
			 * We continue with the search, just in
			 * case there's an even higher prio task
L
Lucas De Marchi 已提交
1783
			 * in another runqueue. (low likelihood
1784 1785 1786
			 * but possible)
			 */
		}
P
Peter Zijlstra 已提交
1787
skip:
1788
		double_unlock_balance(this_rq, src_rq);
1789 1790 1791 1792 1793
	}

	return ret;
}

1794
static void pre_schedule_rt(struct rq *rq, struct task_struct *prev)
1795 1796
{
	/* Try to pull RT tasks here if we lower this rq's prio */
Y
Yong Zhang 已提交
1797
	if (rq->rt.highest_prio.curr > prev->prio)
1798 1799 1800
		pull_rt_task(rq);
}

1801
static void post_schedule_rt(struct rq *rq)
S
Steven Rostedt 已提交
1802
{
1803
	push_rt_tasks(rq);
S
Steven Rostedt 已提交
1804 1805
}

1806 1807 1808 1809
/*
 * If we are not running and we are not going to reschedule soon, we should
 * try to push tasks away now
 */
1810
static void task_woken_rt(struct rq *rq, struct task_struct *p)
1811
{
1812
	if (!task_running(rq, p) &&
1813
	    !test_tsk_need_resched(rq->curr) &&
1814
	    has_pushable_tasks(rq) &&
1815
	    p->nr_cpus_allowed > 1 &&
1816
	    rt_task(rq->curr) &&
1817
	    (rq->curr->nr_cpus_allowed < 2 ||
1818
	     rq->curr->prio <= p->prio))
1819 1820 1821
		push_rt_tasks(rq);
}

1822
static void set_cpus_allowed_rt(struct task_struct *p,
1823
				const struct cpumask *new_mask)
1824
{
1825 1826
	struct rq *rq;
	int weight;
1827 1828 1829

	BUG_ON(!rt_task(p));

1830 1831
	if (!p->on_rq)
		return;
1832

1833
	weight = cpumask_weight(new_mask);
1834

1835 1836 1837 1838
	/*
	 * Only update if the process changes its state from whether it
	 * can migrate or not.
	 */
1839
	if ((p->nr_cpus_allowed > 1) == (weight > 1))
1840
		return;
1841

1842
	rq = task_rq(p);
1843

1844 1845 1846 1847 1848 1849 1850 1851 1852 1853 1854 1855
	/*
	 * The process used to be able to migrate OR it can now migrate
	 */
	if (weight <= 1) {
		if (!task_current(rq, p))
			dequeue_pushable_task(rq, p);
		BUG_ON(!rq->rt.rt_nr_migratory);
		rq->rt.rt_nr_migratory--;
	} else {
		if (!task_current(rq, p))
			enqueue_pushable_task(rq, p);
		rq->rt.rt_nr_migratory++;
1856
	}
1857 1858

	update_rt_migration(&rq->rt);
1859
}
1860

1861
/* Assumes rq->lock is held */
1862
static void rq_online_rt(struct rq *rq)
1863 1864 1865
{
	if (rq->rt.overloaded)
		rt_set_overload(rq);
1866

P
Peter Zijlstra 已提交
1867 1868
	__enable_runtime(rq);

1869
	cpupri_set(&rq->rd->cpupri, rq->cpu, rq->rt.highest_prio.curr);
1870 1871 1872
}

/* Assumes rq->lock is held */
1873
static void rq_offline_rt(struct rq *rq)
1874 1875 1876
{
	if (rq->rt.overloaded)
		rt_clear_overload(rq);
1877

P
Peter Zijlstra 已提交
1878 1879
	__disable_runtime(rq);

1880
	cpupri_set(&rq->rd->cpupri, rq->cpu, CPUPRI_INVALID);
1881
}
1882 1883 1884 1885 1886

/*
 * When switch from the rt queue, we bring ourselves to a position
 * that we might want to pull RT tasks from other runqueues.
 */
P
Peter Zijlstra 已提交
1887
static void switched_from_rt(struct rq *rq, struct task_struct *p)
1888 1889 1890 1891 1892 1893 1894 1895
{
	/*
	 * If there are other RT tasks then we will reschedule
	 * and the scheduling of the other RT tasks will handle
	 * the balancing. But if we are the last RT task
	 * we may need to handle the pulling of RT tasks
	 * now.
	 */
P
Peter Zijlstra 已提交
1896
	if (p->on_rq && !rq->rt.rt_nr_running)
1897 1898
		pull_rt_task(rq);
}
1899

1900
void init_sched_rt_class(void)
1901 1902 1903
{
	unsigned int i;

1904
	for_each_possible_cpu(i) {
1905
		zalloc_cpumask_var_node(&per_cpu(local_cpu_mask, i),
1906
					GFP_KERNEL, cpu_to_node(i));
1907
	}
1908
}
1909 1910 1911 1912 1913 1914 1915
#endif /* CONFIG_SMP */

/*
 * When switching a task to RT, we may overload the runqueue
 * with RT tasks. In this case we try to push them off to
 * other runqueues.
 */
P
Peter Zijlstra 已提交
1916
static void switched_to_rt(struct rq *rq, struct task_struct *p)
1917 1918 1919 1920 1921 1922 1923 1924 1925 1926
{
	int check_resched = 1;

	/*
	 * If we are already running, then there's nothing
	 * that needs to be done. But if we are not running
	 * we may need to preempt the current running task.
	 * If that current running task is also an RT task
	 * then see if we can move to another run queue.
	 */
P
Peter Zijlstra 已提交
1927
	if (p->on_rq && rq->curr != p) {
1928 1929 1930 1931 1932 1933 1934 1935 1936 1937 1938 1939 1940 1941 1942
#ifdef CONFIG_SMP
		if (rq->rt.overloaded && push_rt_task(rq) &&
		    /* Don't resched if we changed runqueues */
		    rq != task_rq(p))
			check_resched = 0;
#endif /* CONFIG_SMP */
		if (check_resched && p->prio < rq->curr->prio)
			resched_task(rq->curr);
	}
}

/*
 * Priority of the task has changed. This may cause
 * us to initiate a push or pull.
 */
P
Peter Zijlstra 已提交
1943 1944
static void
prio_changed_rt(struct rq *rq, struct task_struct *p, int oldprio)
1945
{
P
Peter Zijlstra 已提交
1946
	if (!p->on_rq)
P
Peter Zijlstra 已提交
1947 1948 1949
		return;

	if (rq->curr == p) {
1950 1951 1952 1953 1954 1955 1956 1957 1958
#ifdef CONFIG_SMP
		/*
		 * If our priority decreases while running, we
		 * may need to pull tasks to this runqueue.
		 */
		if (oldprio < p->prio)
			pull_rt_task(rq);
		/*
		 * If there's a higher priority task waiting to run
1959 1960 1961
		 * 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.
1962
		 */
1963
		if (p->prio > rq->rt.highest_prio.curr && rq->curr == p)
1964 1965 1966 1967 1968
			resched_task(p);
#else
		/* For UP simply resched on drop of prio */
		if (oldprio < p->prio)
			resched_task(p);
S
Steven Rostedt 已提交
1969
#endif /* CONFIG_SMP */
1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980
	} else {
		/*
		 * This task is not running, but if it is
		 * greater than the current running task
		 * then reschedule.
		 */
		if (p->prio < rq->curr->prio)
			resched_task(rq->curr);
	}
}

1981 1982 1983 1984
static void watchdog(struct rq *rq, struct task_struct *p)
{
	unsigned long soft, hard;

1985 1986 1987
	/* max may change after cur was read, this will be fixed next tick */
	soft = task_rlimit(p, RLIMIT_RTTIME);
	hard = task_rlimit_max(p, RLIMIT_RTTIME);
1988 1989 1990 1991 1992 1993

	if (soft != RLIM_INFINITY) {
		unsigned long next;

		p->rt.timeout++;
		next = DIV_ROUND_UP(min(soft, hard), USEC_PER_SEC/HZ);
1994
		if (p->rt.timeout > next)
1995
			p->cputime_expires.sched_exp = p->se.sum_exec_runtime;
1996 1997
	}
}
I
Ingo Molnar 已提交
1998

P
Peter Zijlstra 已提交
1999
static void task_tick_rt(struct rq *rq, struct task_struct *p, int queued)
I
Ingo Molnar 已提交
2000
{
2001 2002
	struct sched_rt_entity *rt_se = &p->rt;

2003 2004
	update_curr_rt(rq);

2005 2006
	watchdog(rq, p);

I
Ingo Molnar 已提交
2007 2008 2009 2010 2011 2012 2013
	/*
	 * RR tasks need a special form of timeslice management.
	 * FIFO tasks have no timeslices.
	 */
	if (p->policy != SCHED_RR)
		return;

P
Peter Zijlstra 已提交
2014
	if (--p->rt.time_slice)
I
Ingo Molnar 已提交
2015 2016
		return;

2017
	p->rt.time_slice = RR_TIMESLICE;
I
Ingo Molnar 已提交
2018

2019
	/*
2020 2021
	 * Requeue to the end of queue if we (and all of our ancestors) are the
	 * only element on the queue
2022
	 */
2023 2024 2025 2026 2027 2028
	for_each_sched_rt_entity(rt_se) {
		if (rt_se->run_list.prev != rt_se->run_list.next) {
			requeue_task_rt(rq, p, 0);
			set_tsk_need_resched(p);
			return;
		}
2029
	}
I
Ingo Molnar 已提交
2030 2031
}

2032 2033 2034 2035
static void set_curr_task_rt(struct rq *rq)
{
	struct task_struct *p = rq->curr;

2036
	p->se.exec_start = rq->clock_task;
2037 2038 2039

	/* The running task is never eligible for pushing */
	dequeue_pushable_task(rq, p);
2040 2041
}

2042
static unsigned int get_rr_interval_rt(struct rq *rq, struct task_struct *task)
2043 2044 2045 2046 2047
{
	/*
	 * Time slice is 0 for SCHED_FIFO tasks
	 */
	if (task->policy == SCHED_RR)
2048
		return RR_TIMESLICE;
2049 2050 2051 2052
	else
		return 0;
}

2053
const struct sched_class rt_sched_class = {
2054
	.next			= &fair_sched_class,
I
Ingo Molnar 已提交
2055 2056 2057 2058 2059 2060 2061 2062 2063
	.enqueue_task		= enqueue_task_rt,
	.dequeue_task		= dequeue_task_rt,
	.yield_task		= yield_task_rt,

	.check_preempt_curr	= check_preempt_curr_rt,

	.pick_next_task		= pick_next_task_rt,
	.put_prev_task		= put_prev_task_rt,

2064
#ifdef CONFIG_SMP
L
Li Zefan 已提交
2065 2066
	.select_task_rq		= select_task_rq_rt,

2067
	.set_cpus_allowed       = set_cpus_allowed_rt,
2068 2069
	.rq_online              = rq_online_rt,
	.rq_offline             = rq_offline_rt,
2070 2071
	.pre_schedule		= pre_schedule_rt,
	.post_schedule		= post_schedule_rt,
2072
	.task_woken		= task_woken_rt,
2073
	.switched_from		= switched_from_rt,
2074
#endif
I
Ingo Molnar 已提交
2075

2076
	.set_curr_task          = set_curr_task_rt,
I
Ingo Molnar 已提交
2077
	.task_tick		= task_tick_rt,
2078

2079 2080
	.get_rr_interval	= get_rr_interval_rt,

2081 2082
	.prio_changed		= prio_changed_rt,
	.switched_to		= switched_to_rt,
I
Ingo Molnar 已提交
2083
};
2084 2085 2086 2087

#ifdef CONFIG_SCHED_DEBUG
extern void print_rt_rq(struct seq_file *m, int cpu, struct rt_rq *rt_rq);

2088
void print_rt_stats(struct seq_file *m, int cpu)
2089
{
C
Cheng Xu 已提交
2090
	rt_rq_iter_t iter;
2091 2092 2093
	struct rt_rq *rt_rq;

	rcu_read_lock();
C
Cheng Xu 已提交
2094
	for_each_rt_rq(rt_rq, iter, cpu_rq(cpu))
2095 2096 2097
		print_rt_rq(m, cpu, rt_rq);
	rcu_read_unlock();
}
2098
#endif /* CONFIG_SCHED_DEBUG */