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synced 2024-08-27 03:10:12 +00:00
![Rafael J. Wysocki](/assets/img/avatar_default.png)
All of the callers of cpufreq_update_util() pass rq_clock(rq) to it as the time argument and some of them check whether or not cpu_of(rq) is equal to smp_processor_id() before calling it, so rework it to take a runqueue pointer as the argument and move the rq_clock(rq) evaluation into it. Additionally, provide a wrapper checking cpu_of(rq) against smp_processor_id() for the cpufreq_update_util() callers that need it. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
2370 lines
54 KiB
C
2370 lines
54 KiB
C
/*
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* Real-Time Scheduling Class (mapped to the SCHED_FIFO and SCHED_RR
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* policies)
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*/
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#include "sched.h"
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#include <linux/slab.h>
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#include <linux/irq_work.h>
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int sched_rr_timeslice = RR_TIMESLICE;
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static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun);
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struct rt_bandwidth def_rt_bandwidth;
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static enum hrtimer_restart sched_rt_period_timer(struct hrtimer *timer)
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{
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struct rt_bandwidth *rt_b =
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container_of(timer, struct rt_bandwidth, rt_period_timer);
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int idle = 0;
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int overrun;
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raw_spin_lock(&rt_b->rt_runtime_lock);
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for (;;) {
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overrun = hrtimer_forward_now(timer, rt_b->rt_period);
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if (!overrun)
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break;
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raw_spin_unlock(&rt_b->rt_runtime_lock);
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idle = do_sched_rt_period_timer(rt_b, overrun);
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raw_spin_lock(&rt_b->rt_runtime_lock);
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}
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if (idle)
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rt_b->rt_period_active = 0;
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raw_spin_unlock(&rt_b->rt_runtime_lock);
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return idle ? HRTIMER_NORESTART : HRTIMER_RESTART;
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}
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void init_rt_bandwidth(struct rt_bandwidth *rt_b, u64 period, u64 runtime)
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{
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rt_b->rt_period = ns_to_ktime(period);
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rt_b->rt_runtime = runtime;
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raw_spin_lock_init(&rt_b->rt_runtime_lock);
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hrtimer_init(&rt_b->rt_period_timer,
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CLOCK_MONOTONIC, HRTIMER_MODE_REL);
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rt_b->rt_period_timer.function = sched_rt_period_timer;
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}
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static void start_rt_bandwidth(struct rt_bandwidth *rt_b)
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{
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if (!rt_bandwidth_enabled() || rt_b->rt_runtime == RUNTIME_INF)
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return;
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raw_spin_lock(&rt_b->rt_runtime_lock);
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if (!rt_b->rt_period_active) {
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rt_b->rt_period_active = 1;
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/*
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* SCHED_DEADLINE updates the bandwidth, as a run away
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* RT task with a DL task could hog a CPU. But DL does
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* not reset the period. If a deadline task was running
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* without an RT task running, it can cause RT tasks to
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* throttle when they start up. Kick the timer right away
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* to update the period.
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*/
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hrtimer_forward_now(&rt_b->rt_period_timer, ns_to_ktime(0));
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hrtimer_start_expires(&rt_b->rt_period_timer, HRTIMER_MODE_ABS_PINNED);
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}
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raw_spin_unlock(&rt_b->rt_runtime_lock);
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}
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#if defined(CONFIG_SMP) && defined(HAVE_RT_PUSH_IPI)
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static void push_irq_work_func(struct irq_work *work);
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#endif
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void init_rt_rq(struct rt_rq *rt_rq)
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{
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struct rt_prio_array *array;
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int i;
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array = &rt_rq->active;
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for (i = 0; i < MAX_RT_PRIO; i++) {
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INIT_LIST_HEAD(array->queue + i);
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__clear_bit(i, array->bitmap);
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}
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/* delimiter for bitsearch: */
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__set_bit(MAX_RT_PRIO, array->bitmap);
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#if defined CONFIG_SMP
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rt_rq->highest_prio.curr = MAX_RT_PRIO;
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rt_rq->highest_prio.next = MAX_RT_PRIO;
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rt_rq->rt_nr_migratory = 0;
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rt_rq->overloaded = 0;
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plist_head_init(&rt_rq->pushable_tasks);
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#ifdef HAVE_RT_PUSH_IPI
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rt_rq->push_flags = 0;
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rt_rq->push_cpu = nr_cpu_ids;
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raw_spin_lock_init(&rt_rq->push_lock);
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init_irq_work(&rt_rq->push_work, push_irq_work_func);
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#endif
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#endif /* CONFIG_SMP */
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/* We start is dequeued state, because no RT tasks are queued */
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rt_rq->rt_queued = 0;
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rt_rq->rt_time = 0;
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rt_rq->rt_throttled = 0;
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rt_rq->rt_runtime = 0;
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raw_spin_lock_init(&rt_rq->rt_runtime_lock);
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}
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#ifdef CONFIG_RT_GROUP_SCHED
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static void destroy_rt_bandwidth(struct rt_bandwidth *rt_b)
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{
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hrtimer_cancel(&rt_b->rt_period_timer);
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}
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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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{
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#ifdef CONFIG_SCHED_DEBUG
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WARN_ON_ONCE(!rt_entity_is_task(rt_se));
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#endif
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return container_of(rt_se, struct task_struct, rt);
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}
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static inline struct rq *rq_of_rt_rq(struct rt_rq *rt_rq)
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{
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return rt_rq->rq;
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}
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static inline struct rt_rq *rt_rq_of_se(struct sched_rt_entity *rt_se)
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{
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return rt_se->rt_rq;
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}
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static inline struct rq *rq_of_rt_se(struct sched_rt_entity *rt_se)
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{
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struct rt_rq *rt_rq = rt_se->rt_rq;
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return rt_rq->rq;
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}
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void free_rt_sched_group(struct task_group *tg)
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{
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int i;
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if (tg->rt_se)
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destroy_rt_bandwidth(&tg->rt_bandwidth);
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for_each_possible_cpu(i) {
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if (tg->rt_rq)
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kfree(tg->rt_rq[i]);
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if (tg->rt_se)
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kfree(tg->rt_se[i]);
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}
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kfree(tg->rt_rq);
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kfree(tg->rt_se);
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}
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void init_tg_rt_entry(struct task_group *tg, struct rt_rq *rt_rq,
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struct sched_rt_entity *rt_se, int cpu,
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struct sched_rt_entity *parent)
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{
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struct rq *rq = cpu_rq(cpu);
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rt_rq->highest_prio.curr = MAX_RT_PRIO;
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rt_rq->rt_nr_boosted = 0;
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rt_rq->rq = rq;
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rt_rq->tg = tg;
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tg->rt_rq[cpu] = rt_rq;
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tg->rt_se[cpu] = rt_se;
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if (!rt_se)
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return;
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if (!parent)
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rt_se->rt_rq = &rq->rt;
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else
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rt_se->rt_rq = parent->my_q;
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rt_se->my_q = rt_rq;
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rt_se->parent = parent;
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INIT_LIST_HEAD(&rt_se->run_list);
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}
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int alloc_rt_sched_group(struct task_group *tg, struct task_group *parent)
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{
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struct rt_rq *rt_rq;
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struct sched_rt_entity *rt_se;
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int i;
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tg->rt_rq = kzalloc(sizeof(rt_rq) * nr_cpu_ids, GFP_KERNEL);
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if (!tg->rt_rq)
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goto err;
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tg->rt_se = kzalloc(sizeof(rt_se) * nr_cpu_ids, GFP_KERNEL);
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if (!tg->rt_se)
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goto err;
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init_rt_bandwidth(&tg->rt_bandwidth,
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ktime_to_ns(def_rt_bandwidth.rt_period), 0);
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for_each_possible_cpu(i) {
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rt_rq = kzalloc_node(sizeof(struct rt_rq),
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GFP_KERNEL, cpu_to_node(i));
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if (!rt_rq)
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goto err;
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rt_se = kzalloc_node(sizeof(struct sched_rt_entity),
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GFP_KERNEL, cpu_to_node(i));
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if (!rt_se)
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goto err_free_rq;
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init_rt_rq(rt_rq);
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rt_rq->rt_runtime = tg->rt_bandwidth.rt_runtime;
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init_tg_rt_entry(tg, rt_rq, rt_se, i, parent->rt_se[i]);
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}
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return 1;
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err_free_rq:
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kfree(rt_rq);
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err:
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return 0;
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}
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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)
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{
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return container_of(rt_se, struct task_struct, rt);
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}
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static inline struct rq *rq_of_rt_rq(struct rt_rq *rt_rq)
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{
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return container_of(rt_rq, struct rq, rt);
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}
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static inline struct rq *rq_of_rt_se(struct sched_rt_entity *rt_se)
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{
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struct task_struct *p = rt_task_of(rt_se);
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return task_rq(p);
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}
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static inline struct rt_rq *rt_rq_of_se(struct sched_rt_entity *rt_se)
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{
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struct rq *rq = rq_of_rt_se(rt_se);
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return &rq->rt;
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}
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void free_rt_sched_group(struct task_group *tg) { }
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int alloc_rt_sched_group(struct task_group *tg, struct task_group *parent)
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{
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return 1;
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}
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#endif /* CONFIG_RT_GROUP_SCHED */
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#ifdef CONFIG_SMP
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static void pull_rt_task(struct rq *this_rq);
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static inline bool need_pull_rt_task(struct rq *rq, struct task_struct *prev)
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{
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/* Try to pull RT tasks here if we lower this rq's prio */
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return rq->rt.highest_prio.curr > prev->prio;
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}
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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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{
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if (!rq->online)
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return;
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cpumask_set_cpu(rq->cpu, rq->rd->rto_mask);
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/*
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* Make sure the mask is visible before we set
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* the overload count. That is checked to determine
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* if we should look at the mask. It would be a shame
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* if we looked at the mask, but the mask was not
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* updated yet.
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*
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* Matched by the barrier in pull_rt_task().
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*/
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smp_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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{
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if (!rq->online)
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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) {
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rt_set_overload(rq_of_rt_rq(rt_rq));
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rt_rq->overloaded = 1;
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}
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} else if (rt_rq->overloaded) {
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rt_clear_overload(rq_of_rt_rq(rt_rq));
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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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{
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struct task_struct *p;
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if (!rt_entity_is_task(rt_se))
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return;
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p = rt_task_of(rt_se);
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rt_rq = &rq_of_rt_rq(rt_rq)->rt;
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rt_rq->rt_nr_total++;
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if (tsk_nr_cpus_allowed(p) > 1)
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rt_rq->rt_nr_migratory++;
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update_rt_migration(rt_rq);
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}
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static void dec_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
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{
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struct task_struct *p;
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if (!rt_entity_is_task(rt_se))
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return;
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p = rt_task_of(rt_se);
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rt_rq = &rq_of_rt_rq(rt_rq)->rt;
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rt_rq->rt_nr_total--;
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if (tsk_nr_cpus_allowed(p) > 1)
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rt_rq->rt_nr_migratory--;
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update_rt_migration(rt_rq);
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}
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static inline int has_pushable_tasks(struct rq *rq)
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{
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return !plist_head_empty(&rq->rt.pushable_tasks);
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}
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static DEFINE_PER_CPU(struct callback_head, rt_push_head);
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static DEFINE_PER_CPU(struct callback_head, rt_pull_head);
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static void push_rt_tasks(struct rq *);
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static void pull_rt_task(struct rq *);
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static inline void queue_push_tasks(struct rq *rq)
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{
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if (!has_pushable_tasks(rq))
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return;
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queue_balance_callback(rq, &per_cpu(rt_push_head, rq->cpu), push_rt_tasks);
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}
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static inline void queue_pull_task(struct rq *rq)
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{
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queue_balance_callback(rq, &per_cpu(rt_pull_head, rq->cpu), pull_rt_task);
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}
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static void enqueue_pushable_task(struct rq *rq, struct task_struct *p)
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{
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plist_del(&p->pushable_tasks, &rq->rt.pushable_tasks);
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plist_node_init(&p->pushable_tasks, p->prio);
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plist_add(&p->pushable_tasks, &rq->rt.pushable_tasks);
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/* Update the highest prio pushable task */
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if (p->prio < rq->rt.highest_prio.next)
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rq->rt.highest_prio.next = p->prio;
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}
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static void dequeue_pushable_task(struct rq *rq, struct task_struct *p)
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{
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plist_del(&p->pushable_tasks, &rq->rt.pushable_tasks);
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/* Update the new highest prio pushable task */
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if (has_pushable_tasks(rq)) {
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p = plist_first_entry(&rq->rt.pushable_tasks,
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struct task_struct, pushable_tasks);
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rq->rt.highest_prio.next = p->prio;
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} else
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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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{
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}
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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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{
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}
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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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{
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}
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static inline bool need_pull_rt_task(struct rq *rq, struct task_struct *prev)
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{
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return false;
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}
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static inline void pull_rt_task(struct rq *this_rq)
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{
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}
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static inline void queue_push_tasks(struct rq *rq)
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{
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}
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#endif /* CONFIG_SMP */
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static void enqueue_top_rt_rq(struct rt_rq *rt_rq);
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static void dequeue_top_rt_rq(struct rt_rq *rt_rq);
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static inline int on_rt_rq(struct sched_rt_entity *rt_se)
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{
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return rt_se->on_rq;
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}
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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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{
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if (!rt_rq->tg)
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return RUNTIME_INF;
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return rt_rq->rt_runtime;
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}
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|
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static inline u64 sched_rt_period(struct rt_rq *rt_rq)
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{
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return ktime_to_ns(rt_rq->tg->rt_bandwidth.rt_period);
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}
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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)
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|
{
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do {
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tg = list_entry_rcu(tg->list.next,
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typeof(struct task_group), list);
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} while (&tg->list != &task_groups && task_group_is_autogroup(tg));
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|
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if (&tg->list == &task_groups)
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tg = NULL;
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return tg;
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}
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|
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#define for_each_rt_rq(rt_rq, iter, rq) \
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for (iter = container_of(&task_groups, typeof(*iter), list); \
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(iter = next_task_group(iter)) && \
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(rt_rq = iter->rt_rq[cpu_of(rq)]);)
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|
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#define for_each_sched_rt_entity(rt_se) \
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for (; rt_se; rt_se = rt_se->parent)
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static inline struct rt_rq *group_rt_rq(struct sched_rt_entity *rt_se)
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{
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return rt_se->my_q;
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}
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static void enqueue_rt_entity(struct sched_rt_entity *rt_se, unsigned int flags);
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static void dequeue_rt_entity(struct sched_rt_entity *rt_se, unsigned int flags);
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static void sched_rt_rq_enqueue(struct rt_rq *rt_rq)
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{
|
|
struct task_struct *curr = rq_of_rt_rq(rt_rq)->curr;
|
|
struct rq *rq = rq_of_rt_rq(rt_rq);
|
|
struct sched_rt_entity *rt_se;
|
|
|
|
int cpu = cpu_of(rq);
|
|
|
|
rt_se = rt_rq->tg->rt_se[cpu];
|
|
|
|
if (rt_rq->rt_nr_running) {
|
|
if (!rt_se)
|
|
enqueue_top_rt_rq(rt_rq);
|
|
else if (!on_rt_rq(rt_se))
|
|
enqueue_rt_entity(rt_se, 0);
|
|
|
|
if (rt_rq->highest_prio.curr < curr->prio)
|
|
resched_curr(rq);
|
|
}
|
|
}
|
|
|
|
static void sched_rt_rq_dequeue(struct rt_rq *rt_rq)
|
|
{
|
|
struct sched_rt_entity *rt_se;
|
|
int cpu = cpu_of(rq_of_rt_rq(rt_rq));
|
|
|
|
rt_se = rt_rq->tg->rt_se[cpu];
|
|
|
|
if (!rt_se)
|
|
dequeue_top_rt_rq(rt_rq);
|
|
else if (on_rt_rq(rt_se))
|
|
dequeue_rt_entity(rt_se, 0);
|
|
}
|
|
|
|
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;
|
|
}
|
|
|
|
#ifdef CONFIG_SMP
|
|
static inline const struct cpumask *sched_rt_period_mask(void)
|
|
{
|
|
return this_rq()->rd->span;
|
|
}
|
|
#else
|
|
static inline const struct cpumask *sched_rt_period_mask(void)
|
|
{
|
|
return cpu_online_mask;
|
|
}
|
|
#endif
|
|
|
|
static inline
|
|
struct rt_rq *sched_rt_period_rt_rq(struct rt_bandwidth *rt_b, int cpu)
|
|
{
|
|
return container_of(rt_b, struct task_group, rt_bandwidth)->rt_rq[cpu];
|
|
}
|
|
|
|
static inline struct rt_bandwidth *sched_rt_bandwidth(struct rt_rq *rt_rq)
|
|
{
|
|
return &rt_rq->tg->rt_bandwidth;
|
|
}
|
|
|
|
#else /* !CONFIG_RT_GROUP_SCHED */
|
|
|
|
static inline u64 sched_rt_runtime(struct rt_rq *rt_rq)
|
|
{
|
|
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);
|
|
}
|
|
|
|
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)
|
|
|
|
#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;
|
|
}
|
|
|
|
static inline void sched_rt_rq_enqueue(struct rt_rq *rt_rq)
|
|
{
|
|
struct rq *rq = rq_of_rt_rq(rt_rq);
|
|
|
|
if (!rt_rq->rt_nr_running)
|
|
return;
|
|
|
|
enqueue_top_rt_rq(rt_rq);
|
|
resched_curr(rq);
|
|
}
|
|
|
|
static inline void sched_rt_rq_dequeue(struct rt_rq *rt_rq)
|
|
{
|
|
dequeue_top_rt_rq(rt_rq);
|
|
}
|
|
|
|
static inline int rt_rq_throttled(struct rt_rq *rt_rq)
|
|
{
|
|
return rt_rq->rt_throttled;
|
|
}
|
|
|
|
static inline const struct cpumask *sched_rt_period_mask(void)
|
|
{
|
|
return cpu_online_mask;
|
|
}
|
|
|
|
static inline
|
|
struct rt_rq *sched_rt_period_rt_rq(struct rt_bandwidth *rt_b, int cpu)
|
|
{
|
|
return &cpu_rq(cpu)->rt;
|
|
}
|
|
|
|
static inline struct rt_bandwidth *sched_rt_bandwidth(struct rt_rq *rt_rq)
|
|
{
|
|
return &def_rt_bandwidth;
|
|
}
|
|
|
|
#endif /* CONFIG_RT_GROUP_SCHED */
|
|
|
|
bool sched_rt_bandwidth_account(struct rt_rq *rt_rq)
|
|
{
|
|
struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
|
|
|
|
return (hrtimer_active(&rt_b->rt_period_timer) ||
|
|
rt_rq->rt_time < rt_b->rt_runtime);
|
|
}
|
|
|
|
#ifdef CONFIG_SMP
|
|
/*
|
|
* We ran out of runtime, see if we can borrow some from our neighbours.
|
|
*/
|
|
static void do_balance_runtime(struct rt_rq *rt_rq)
|
|
{
|
|
struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
|
|
struct root_domain *rd = rq_of_rt_rq(rt_rq)->rd;
|
|
int i, weight;
|
|
u64 rt_period;
|
|
|
|
weight = cpumask_weight(rd->span);
|
|
|
|
raw_spin_lock(&rt_b->rt_runtime_lock);
|
|
rt_period = ktime_to_ns(rt_b->rt_period);
|
|
for_each_cpu(i, rd->span) {
|
|
struct rt_rq *iter = sched_rt_period_rt_rq(rt_b, i);
|
|
s64 diff;
|
|
|
|
if (iter == rt_rq)
|
|
continue;
|
|
|
|
raw_spin_lock(&iter->rt_runtime_lock);
|
|
/*
|
|
* 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.
|
|
*/
|
|
if (iter->rt_runtime == RUNTIME_INF)
|
|
goto next;
|
|
|
|
/*
|
|
* From runqueues with spare time, take 1/n part of their
|
|
* spare time, but no more than our period.
|
|
*/
|
|
diff = iter->rt_runtime - iter->rt_time;
|
|
if (diff > 0) {
|
|
diff = div_u64((u64)diff, weight);
|
|
if (rt_rq->rt_runtime + diff > rt_period)
|
|
diff = rt_period - rt_rq->rt_runtime;
|
|
iter->rt_runtime -= diff;
|
|
rt_rq->rt_runtime += diff;
|
|
if (rt_rq->rt_runtime == rt_period) {
|
|
raw_spin_unlock(&iter->rt_runtime_lock);
|
|
break;
|
|
}
|
|
}
|
|
next:
|
|
raw_spin_unlock(&iter->rt_runtime_lock);
|
|
}
|
|
raw_spin_unlock(&rt_b->rt_runtime_lock);
|
|
}
|
|
|
|
/*
|
|
* Ensure this RQ takes back all the runtime it lend to its neighbours.
|
|
*/
|
|
static void __disable_runtime(struct rq *rq)
|
|
{
|
|
struct root_domain *rd = rq->rd;
|
|
rt_rq_iter_t iter;
|
|
struct rt_rq *rt_rq;
|
|
|
|
if (unlikely(!scheduler_running))
|
|
return;
|
|
|
|
for_each_rt_rq(rt_rq, iter, rq) {
|
|
struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
|
|
s64 want;
|
|
int i;
|
|
|
|
raw_spin_lock(&rt_b->rt_runtime_lock);
|
|
raw_spin_lock(&rt_rq->rt_runtime_lock);
|
|
/*
|
|
* 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.
|
|
*/
|
|
if (rt_rq->rt_runtime == RUNTIME_INF ||
|
|
rt_rq->rt_runtime == rt_b->rt_runtime)
|
|
goto balanced;
|
|
raw_spin_unlock(&rt_rq->rt_runtime_lock);
|
|
|
|
/*
|
|
* 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.
|
|
*/
|
|
want = rt_b->rt_runtime - rt_rq->rt_runtime;
|
|
|
|
/*
|
|
* Greedy reclaim, take back as much as we can.
|
|
*/
|
|
for_each_cpu(i, rd->span) {
|
|
struct rt_rq *iter = sched_rt_period_rt_rq(rt_b, i);
|
|
s64 diff;
|
|
|
|
/*
|
|
* Can't reclaim from ourselves or disabled runqueues.
|
|
*/
|
|
if (iter == rt_rq || iter->rt_runtime == RUNTIME_INF)
|
|
continue;
|
|
|
|
raw_spin_lock(&iter->rt_runtime_lock);
|
|
if (want > 0) {
|
|
diff = min_t(s64, iter->rt_runtime, want);
|
|
iter->rt_runtime -= diff;
|
|
want -= diff;
|
|
} else {
|
|
iter->rt_runtime -= want;
|
|
want -= want;
|
|
}
|
|
raw_spin_unlock(&iter->rt_runtime_lock);
|
|
|
|
if (!want)
|
|
break;
|
|
}
|
|
|
|
raw_spin_lock(&rt_rq->rt_runtime_lock);
|
|
/*
|
|
* We cannot be left wanting - that would mean some runtime
|
|
* leaked out of the system.
|
|
*/
|
|
BUG_ON(want);
|
|
balanced:
|
|
/*
|
|
* Disable all the borrow logic by pretending we have inf
|
|
* runtime - in which case borrowing doesn't make sense.
|
|
*/
|
|
rt_rq->rt_runtime = RUNTIME_INF;
|
|
rt_rq->rt_throttled = 0;
|
|
raw_spin_unlock(&rt_rq->rt_runtime_lock);
|
|
raw_spin_unlock(&rt_b->rt_runtime_lock);
|
|
|
|
/* Make rt_rq available for pick_next_task() */
|
|
sched_rt_rq_enqueue(rt_rq);
|
|
}
|
|
}
|
|
|
|
static void __enable_runtime(struct rq *rq)
|
|
{
|
|
rt_rq_iter_t iter;
|
|
struct rt_rq *rt_rq;
|
|
|
|
if (unlikely(!scheduler_running))
|
|
return;
|
|
|
|
/*
|
|
* Reset each runqueue's bandwidth settings
|
|
*/
|
|
for_each_rt_rq(rt_rq, iter, rq) {
|
|
struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
|
|
|
|
raw_spin_lock(&rt_b->rt_runtime_lock);
|
|
raw_spin_lock(&rt_rq->rt_runtime_lock);
|
|
rt_rq->rt_runtime = rt_b->rt_runtime;
|
|
rt_rq->rt_time = 0;
|
|
rt_rq->rt_throttled = 0;
|
|
raw_spin_unlock(&rt_rq->rt_runtime_lock);
|
|
raw_spin_unlock(&rt_b->rt_runtime_lock);
|
|
}
|
|
}
|
|
|
|
static void balance_runtime(struct rt_rq *rt_rq)
|
|
{
|
|
if (!sched_feat(RT_RUNTIME_SHARE))
|
|
return;
|
|
|
|
if (rt_rq->rt_time > rt_rq->rt_runtime) {
|
|
raw_spin_unlock(&rt_rq->rt_runtime_lock);
|
|
do_balance_runtime(rt_rq);
|
|
raw_spin_lock(&rt_rq->rt_runtime_lock);
|
|
}
|
|
}
|
|
#else /* !CONFIG_SMP */
|
|
static inline void balance_runtime(struct rt_rq *rt_rq) {}
|
|
#endif /* CONFIG_SMP */
|
|
|
|
static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun)
|
|
{
|
|
int i, idle = 1, throttled = 0;
|
|
const struct cpumask *span;
|
|
|
|
span = sched_rt_period_mask();
|
|
#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
|
|
for_each_cpu(i, span) {
|
|
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);
|
|
|
|
raw_spin_lock(&rq->lock);
|
|
if (rt_rq->rt_time) {
|
|
u64 runtime;
|
|
|
|
raw_spin_lock(&rt_rq->rt_runtime_lock);
|
|
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;
|
|
|
|
/*
|
|
* When we're idle and a woken (rt) task is
|
|
* throttled check_preempt_curr() will set
|
|
* skip_update and the time between the wakeup
|
|
* and this unthrottle will get accounted as
|
|
* 'runtime'.
|
|
*/
|
|
if (rt_rq->rt_nr_running && rq->curr == rq->idle)
|
|
rq_clock_skip_update(rq, false);
|
|
}
|
|
if (rt_rq->rt_time || rt_rq->rt_nr_running)
|
|
idle = 0;
|
|
raw_spin_unlock(&rt_rq->rt_runtime_lock);
|
|
} else if (rt_rq->rt_nr_running) {
|
|
idle = 0;
|
|
if (!rt_rq_throttled(rt_rq))
|
|
enqueue = 1;
|
|
}
|
|
if (rt_rq->rt_throttled)
|
|
throttled = 1;
|
|
|
|
if (enqueue)
|
|
sched_rt_rq_enqueue(rt_rq);
|
|
raw_spin_unlock(&rq->lock);
|
|
}
|
|
|
|
if (!throttled && (!rt_bandwidth_enabled() || rt_b->rt_runtime == RUNTIME_INF))
|
|
return 1;
|
|
|
|
return idle;
|
|
}
|
|
|
|
static inline int rt_se_prio(struct sched_rt_entity *rt_se)
|
|
{
|
|
#ifdef CONFIG_RT_GROUP_SCHED
|
|
struct rt_rq *rt_rq = group_rt_rq(rt_se);
|
|
|
|
if (rt_rq)
|
|
return rt_rq->highest_prio.curr;
|
|
#endif
|
|
|
|
return rt_task_of(rt_se)->prio;
|
|
}
|
|
|
|
static int sched_rt_runtime_exceeded(struct rt_rq *rt_rq)
|
|
{
|
|
u64 runtime = sched_rt_runtime(rt_rq);
|
|
|
|
if (rt_rq->rt_throttled)
|
|
return rt_rq_throttled(rt_rq);
|
|
|
|
if (runtime >= sched_rt_period(rt_rq))
|
|
return 0;
|
|
|
|
balance_runtime(rt_rq);
|
|
runtime = sched_rt_runtime(rt_rq);
|
|
if (runtime == RUNTIME_INF)
|
|
return 0;
|
|
|
|
if (rt_rq->rt_time > runtime) {
|
|
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)) {
|
|
rt_rq->rt_throttled = 1;
|
|
printk_deferred_once("sched: RT throttling activated\n");
|
|
} 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;
|
|
}
|
|
|
|
if (rt_rq_throttled(rt_rq)) {
|
|
sched_rt_rq_dequeue(rt_rq);
|
|
return 1;
|
|
}
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Update the current task's runtime statistics. Skip current tasks that
|
|
* are not in our scheduling class.
|
|
*/
|
|
static void update_curr_rt(struct rq *rq)
|
|
{
|
|
struct task_struct *curr = rq->curr;
|
|
struct sched_rt_entity *rt_se = &curr->rt;
|
|
u64 delta_exec;
|
|
|
|
if (curr->sched_class != &rt_sched_class)
|
|
return;
|
|
|
|
delta_exec = rq_clock_task(rq) - curr->se.exec_start;
|
|
if (unlikely((s64)delta_exec <= 0))
|
|
return;
|
|
|
|
/* Kick cpufreq (see the comment in kernel/sched/sched.h). */
|
|
cpufreq_update_this_cpu(rq, SCHED_CPUFREQ_RT);
|
|
|
|
schedstat_set(curr->se.statistics.exec_max,
|
|
max(curr->se.statistics.exec_max, delta_exec));
|
|
|
|
curr->se.sum_exec_runtime += delta_exec;
|
|
account_group_exec_runtime(curr, delta_exec);
|
|
|
|
curr->se.exec_start = rq_clock_task(rq);
|
|
cpuacct_charge(curr, delta_exec);
|
|
|
|
sched_rt_avg_update(rq, delta_exec);
|
|
|
|
if (!rt_bandwidth_enabled())
|
|
return;
|
|
|
|
for_each_sched_rt_entity(rt_se) {
|
|
struct rt_rq *rt_rq = rt_rq_of_se(rt_se);
|
|
|
|
if (sched_rt_runtime(rt_rq) != RUNTIME_INF) {
|
|
raw_spin_lock(&rt_rq->rt_runtime_lock);
|
|
rt_rq->rt_time += delta_exec;
|
|
if (sched_rt_runtime_exceeded(rt_rq))
|
|
resched_curr(rq);
|
|
raw_spin_unlock(&rt_rq->rt_runtime_lock);
|
|
}
|
|
}
|
|
}
|
|
|
|
static void
|
|
dequeue_top_rt_rq(struct rt_rq *rt_rq)
|
|
{
|
|
struct rq *rq = rq_of_rt_rq(rt_rq);
|
|
|
|
BUG_ON(&rq->rt != rt_rq);
|
|
|
|
if (!rt_rq->rt_queued)
|
|
return;
|
|
|
|
BUG_ON(!rq->nr_running);
|
|
|
|
sub_nr_running(rq, rt_rq->rt_nr_running);
|
|
rt_rq->rt_queued = 0;
|
|
}
|
|
|
|
static void
|
|
enqueue_top_rt_rq(struct rt_rq *rt_rq)
|
|
{
|
|
struct rq *rq = rq_of_rt_rq(rt_rq);
|
|
|
|
BUG_ON(&rq->rt != rt_rq);
|
|
|
|
if (rt_rq->rt_queued)
|
|
return;
|
|
if (rt_rq_throttled(rt_rq) || !rt_rq->rt_nr_running)
|
|
return;
|
|
|
|
add_nr_running(rq, rt_rq->rt_nr_running);
|
|
rt_rq->rt_queued = 1;
|
|
}
|
|
|
|
#if defined CONFIG_SMP
|
|
|
|
static void
|
|
inc_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio)
|
|
{
|
|
struct rq *rq = rq_of_rt_rq(rt_rq);
|
|
|
|
#ifdef CONFIG_RT_GROUP_SCHED
|
|
/*
|
|
* Change rq's cpupri only if rt_rq is the top queue.
|
|
*/
|
|
if (&rq->rt != rt_rq)
|
|
return;
|
|
#endif
|
|
if (rq->online && prio < prev_prio)
|
|
cpupri_set(&rq->rd->cpupri, rq->cpu, prio);
|
|
}
|
|
|
|
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);
|
|
|
|
#ifdef CONFIG_RT_GROUP_SCHED
|
|
/*
|
|
* Change rq's cpupri only if rt_rq is the top queue.
|
|
*/
|
|
if (&rq->rt != rt_rq)
|
|
return;
|
|
#endif
|
|
if (rq->online && rt_rq->highest_prio.curr != prev_prio)
|
|
cpupri_set(&rq->rd->cpupri, rq->cpu, rt_rq->highest_prio.curr);
|
|
}
|
|
|
|
#else /* CONFIG_SMP */
|
|
|
|
static inline
|
|
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 */
|
|
|
|
#if defined CONFIG_SMP || defined CONFIG_RT_GROUP_SCHED
|
|
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;
|
|
|
|
if (rt_rq->rt_nr_running) {
|
|
|
|
WARN_ON(prio < prev_prio);
|
|
|
|
/*
|
|
* This may have been our highest task, and therefore
|
|
* we may have some recomputation to do
|
|
*/
|
|
if (prio == prev_prio) {
|
|
struct rt_prio_array *array = &rt_rq->active;
|
|
|
|
rt_rq->highest_prio.curr =
|
|
sched_find_first_bit(array->bitmap);
|
|
}
|
|
|
|
} else
|
|
rt_rq->highest_prio.curr = MAX_RT_PRIO;
|
|
|
|
dec_rt_prio_smp(rt_rq, prio, prev_prio);
|
|
}
|
|
|
|
#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 */
|
|
|
|
#ifdef CONFIG_RT_GROUP_SCHED
|
|
|
|
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)
|
|
{
|
|
if (rt_se_boosted(rt_se))
|
|
rt_rq->rt_nr_boosted--;
|
|
|
|
WARN_ON(!rt_rq->rt_nr_running && rt_rq->rt_nr_boosted);
|
|
}
|
|
|
|
#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
|
|
unsigned int rt_se_nr_running(struct sched_rt_entity *rt_se)
|
|
{
|
|
struct rt_rq *group_rq = group_rt_rq(rt_se);
|
|
|
|
if (group_rq)
|
|
return group_rq->rt_nr_running;
|
|
else
|
|
return 1;
|
|
}
|
|
|
|
static inline
|
|
unsigned int rt_se_rr_nr_running(struct sched_rt_entity *rt_se)
|
|
{
|
|
struct rt_rq *group_rq = group_rt_rq(rt_se);
|
|
struct task_struct *tsk;
|
|
|
|
if (group_rq)
|
|
return group_rq->rr_nr_running;
|
|
|
|
tsk = rt_task_of(rt_se);
|
|
|
|
return (tsk->policy == SCHED_RR) ? 1 : 0;
|
|
}
|
|
|
|
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 += rt_se_nr_running(rt_se);
|
|
rt_rq->rr_nr_running += rt_se_rr_nr_running(rt_se);
|
|
|
|
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 -= rt_se_nr_running(rt_se);
|
|
rt_rq->rr_nr_running -= rt_se_rr_nr_running(rt_se);
|
|
|
|
dec_rt_prio(rt_rq, rt_se_prio(rt_se));
|
|
dec_rt_migration(rt_se, rt_rq);
|
|
dec_rt_group(rt_se, rt_rq);
|
|
}
|
|
|
|
/*
|
|
* Change rt_se->run_list location unless SAVE && !MOVE
|
|
*
|
|
* assumes ENQUEUE/DEQUEUE flags match
|
|
*/
|
|
static inline bool move_entity(unsigned int flags)
|
|
{
|
|
if ((flags & (DEQUEUE_SAVE | DEQUEUE_MOVE)) == DEQUEUE_SAVE)
|
|
return false;
|
|
|
|
return true;
|
|
}
|
|
|
|
static void __delist_rt_entity(struct sched_rt_entity *rt_se, struct rt_prio_array *array)
|
|
{
|
|
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);
|
|
|
|
rt_se->on_list = 0;
|
|
}
|
|
|
|
static void __enqueue_rt_entity(struct sched_rt_entity *rt_se, unsigned int flags)
|
|
{
|
|
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);
|
|
struct list_head *queue = array->queue + rt_se_prio(rt_se);
|
|
|
|
/*
|
|
* 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)) {
|
|
if (rt_se->on_list)
|
|
__delist_rt_entity(rt_se, array);
|
|
return;
|
|
}
|
|
|
|
if (move_entity(flags)) {
|
|
WARN_ON_ONCE(rt_se->on_list);
|
|
if (flags & ENQUEUE_HEAD)
|
|
list_add(&rt_se->run_list, queue);
|
|
else
|
|
list_add_tail(&rt_se->run_list, queue);
|
|
|
|
__set_bit(rt_se_prio(rt_se), array->bitmap);
|
|
rt_se->on_list = 1;
|
|
}
|
|
rt_se->on_rq = 1;
|
|
|
|
inc_rt_tasks(rt_se, rt_rq);
|
|
}
|
|
|
|
static void __dequeue_rt_entity(struct sched_rt_entity *rt_se, unsigned int flags)
|
|
{
|
|
struct rt_rq *rt_rq = rt_rq_of_se(rt_se);
|
|
struct rt_prio_array *array = &rt_rq->active;
|
|
|
|
if (move_entity(flags)) {
|
|
WARN_ON_ONCE(!rt_se->on_list);
|
|
__delist_rt_entity(rt_se, array);
|
|
}
|
|
rt_se->on_rq = 0;
|
|
|
|
dec_rt_tasks(rt_se, rt_rq);
|
|
}
|
|
|
|
/*
|
|
* Because the prio of an upper entry depends on the lower
|
|
* entries, we must remove entries top - down.
|
|
*/
|
|
static void dequeue_rt_stack(struct sched_rt_entity *rt_se, unsigned int flags)
|
|
{
|
|
struct sched_rt_entity *back = NULL;
|
|
|
|
for_each_sched_rt_entity(rt_se) {
|
|
rt_se->back = back;
|
|
back = rt_se;
|
|
}
|
|
|
|
dequeue_top_rt_rq(rt_rq_of_se(back));
|
|
|
|
for (rt_se = back; rt_se; rt_se = rt_se->back) {
|
|
if (on_rt_rq(rt_se))
|
|
__dequeue_rt_entity(rt_se, flags);
|
|
}
|
|
}
|
|
|
|
static void enqueue_rt_entity(struct sched_rt_entity *rt_se, unsigned int flags)
|
|
{
|
|
struct rq *rq = rq_of_rt_se(rt_se);
|
|
|
|
dequeue_rt_stack(rt_se, flags);
|
|
for_each_sched_rt_entity(rt_se)
|
|
__enqueue_rt_entity(rt_se, flags);
|
|
enqueue_top_rt_rq(&rq->rt);
|
|
}
|
|
|
|
static void dequeue_rt_entity(struct sched_rt_entity *rt_se, unsigned int flags)
|
|
{
|
|
struct rq *rq = rq_of_rt_se(rt_se);
|
|
|
|
dequeue_rt_stack(rt_se, flags);
|
|
|
|
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)
|
|
__enqueue_rt_entity(rt_se, flags);
|
|
}
|
|
enqueue_top_rt_rq(&rq->rt);
|
|
}
|
|
|
|
/*
|
|
* Adding/removing a task to/from a priority array:
|
|
*/
|
|
static void
|
|
enqueue_task_rt(struct rq *rq, struct task_struct *p, int flags)
|
|
{
|
|
struct sched_rt_entity *rt_se = &p->rt;
|
|
|
|
if (flags & ENQUEUE_WAKEUP)
|
|
rt_se->timeout = 0;
|
|
|
|
enqueue_rt_entity(rt_se, flags);
|
|
|
|
if (!task_current(rq, p) && tsk_nr_cpus_allowed(p) > 1)
|
|
enqueue_pushable_task(rq, p);
|
|
}
|
|
|
|
static void dequeue_task_rt(struct rq *rq, struct task_struct *p, int flags)
|
|
{
|
|
struct sched_rt_entity *rt_se = &p->rt;
|
|
|
|
update_curr_rt(rq);
|
|
dequeue_rt_entity(rt_se, flags);
|
|
|
|
dequeue_pushable_task(rq, p);
|
|
}
|
|
|
|
/*
|
|
* Put task to the head or the end of the run list without the overhead of
|
|
* dequeue followed by enqueue.
|
|
*/
|
|
static void
|
|
requeue_rt_entity(struct rt_rq *rt_rq, struct sched_rt_entity *rt_se, int head)
|
|
{
|
|
if (on_rt_rq(rt_se)) {
|
|
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);
|
|
}
|
|
}
|
|
|
|
static void requeue_task_rt(struct rq *rq, struct task_struct *p, int head)
|
|
{
|
|
struct sched_rt_entity *rt_se = &p->rt;
|
|
struct rt_rq *rt_rq;
|
|
|
|
for_each_sched_rt_entity(rt_se) {
|
|
rt_rq = rt_rq_of_se(rt_se);
|
|
requeue_rt_entity(rt_rq, rt_se, head);
|
|
}
|
|
}
|
|
|
|
static void yield_task_rt(struct rq *rq)
|
|
{
|
|
requeue_task_rt(rq, rq->curr, 0);
|
|
}
|
|
|
|
#ifdef CONFIG_SMP
|
|
static int find_lowest_rq(struct task_struct *task);
|
|
|
|
static int
|
|
select_task_rq_rt(struct task_struct *p, int cpu, int sd_flag, int flags)
|
|
{
|
|
struct task_struct *curr;
|
|
struct rq *rq;
|
|
|
|
/* For anything but wake ups, just return the task_cpu */
|
|
if (sd_flag != SD_BALANCE_WAKE && sd_flag != SD_BALANCE_FORK)
|
|
goto out;
|
|
|
|
rq = cpu_rq(cpu);
|
|
|
|
rcu_read_lock();
|
|
curr = READ_ONCE(rq->curr); /* unlocked access */
|
|
|
|
/*
|
|
* If the current task on @p's runqueue is an RT task, then
|
|
* try to see if we can wake this RT task up on another
|
|
* runqueue. Otherwise simply start this RT task
|
|
* on its current runqueue.
|
|
*
|
|
* 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.
|
|
*
|
|
* 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.
|
|
*/
|
|
if (curr && unlikely(rt_task(curr)) &&
|
|
(tsk_nr_cpus_allowed(curr) < 2 ||
|
|
curr->prio <= p->prio)) {
|
|
int target = find_lowest_rq(p);
|
|
|
|
/*
|
|
* Don't bother moving it if the destination CPU is
|
|
* not running a lower priority task.
|
|
*/
|
|
if (target != -1 &&
|
|
p->prio < cpu_rq(target)->rt.highest_prio.curr)
|
|
cpu = target;
|
|
}
|
|
rcu_read_unlock();
|
|
|
|
out:
|
|
return cpu;
|
|
}
|
|
|
|
static void check_preempt_equal_prio(struct rq *rq, struct task_struct *p)
|
|
{
|
|
/*
|
|
* Current can't be migrated, useless to reschedule,
|
|
* let's hope p can move out.
|
|
*/
|
|
if (tsk_nr_cpus_allowed(rq->curr) == 1 ||
|
|
!cpupri_find(&rq->rd->cpupri, rq->curr, NULL))
|
|
return;
|
|
|
|
/*
|
|
* p is migratable, so let's not schedule it and
|
|
* see if it is pushed or pulled somewhere else.
|
|
*/
|
|
if (tsk_nr_cpus_allowed(p) != 1
|
|
&& cpupri_find(&rq->rd->cpupri, p, NULL))
|
|
return;
|
|
|
|
/*
|
|
* 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_curr(rq);
|
|
}
|
|
|
|
#endif /* CONFIG_SMP */
|
|
|
|
/*
|
|
* Preempt the current task with a newly woken task if needed:
|
|
*/
|
|
static void check_preempt_curr_rt(struct rq *rq, struct task_struct *p, int flags)
|
|
{
|
|
if (p->prio < rq->curr->prio) {
|
|
resched_curr(rq);
|
|
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.
|
|
*/
|
|
if (p->prio == rq->curr->prio && !test_tsk_need_resched(rq->curr))
|
|
check_preempt_equal_prio(rq, p);
|
|
#endif
|
|
}
|
|
|
|
static struct sched_rt_entity *pick_next_rt_entity(struct rq *rq,
|
|
struct rt_rq *rt_rq)
|
|
{
|
|
struct rt_prio_array *array = &rt_rq->active;
|
|
struct sched_rt_entity *next = NULL;
|
|
struct list_head *queue;
|
|
int idx;
|
|
|
|
idx = sched_find_first_bit(array->bitmap);
|
|
BUG_ON(idx >= MAX_RT_PRIO);
|
|
|
|
queue = array->queue + idx;
|
|
next = list_entry(queue->next, struct sched_rt_entity, run_list);
|
|
|
|
return next;
|
|
}
|
|
|
|
static struct task_struct *_pick_next_task_rt(struct rq *rq)
|
|
{
|
|
struct sched_rt_entity *rt_se;
|
|
struct task_struct *p;
|
|
struct rt_rq *rt_rq = &rq->rt;
|
|
|
|
do {
|
|
rt_se = pick_next_rt_entity(rq, rt_rq);
|
|
BUG_ON(!rt_se);
|
|
rt_rq = group_rt_rq(rt_se);
|
|
} while (rt_rq);
|
|
|
|
p = rt_task_of(rt_se);
|
|
p->se.exec_start = rq_clock_task(rq);
|
|
|
|
return p;
|
|
}
|
|
|
|
static struct task_struct *
|
|
pick_next_task_rt(struct rq *rq, struct task_struct *prev, struct pin_cookie cookie)
|
|
{
|
|
struct task_struct *p;
|
|
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, cookie);
|
|
pull_rt_task(rq);
|
|
lockdep_repin_lock(&rq->lock, cookie);
|
|
/*
|
|
* 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
|
|
* to re-start task selection.
|
|
*/
|
|
if (unlikely((rq->stop && task_on_rq_queued(rq->stop)) ||
|
|
rq->dl.dl_nr_running))
|
|
return RETRY_TASK;
|
|
}
|
|
|
|
/*
|
|
* We may dequeue prev's rt_rq in put_prev_task().
|
|
* So, we update time before rt_nr_running check.
|
|
*/
|
|
if (prev->sched_class == &rt_sched_class)
|
|
update_curr_rt(rq);
|
|
|
|
if (!rt_rq->rt_queued)
|
|
return NULL;
|
|
|
|
put_prev_task(rq, prev);
|
|
|
|
p = _pick_next_task_rt(rq);
|
|
|
|
/* The running task is never eligible for pushing */
|
|
dequeue_pushable_task(rq, p);
|
|
|
|
queue_push_tasks(rq);
|
|
|
|
return p;
|
|
}
|
|
|
|
static void put_prev_task_rt(struct rq *rq, struct task_struct *p)
|
|
{
|
|
update_curr_rt(rq);
|
|
|
|
/*
|
|
* The previous task needs to be made eligible for pushing
|
|
* if it is still active
|
|
*/
|
|
if (on_rt_rq(&p->rt) && tsk_nr_cpus_allowed(p) > 1)
|
|
enqueue_pushable_task(rq, p);
|
|
}
|
|
|
|
#ifdef CONFIG_SMP
|
|
|
|
/* Only try algorithms three times */
|
|
#define RT_MAX_TRIES 3
|
|
|
|
static int pick_rt_task(struct rq *rq, struct task_struct *p, int cpu)
|
|
{
|
|
if (!task_running(rq, p) &&
|
|
cpumask_test_cpu(cpu, tsk_cpus_allowed(p)))
|
|
return 1;
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Return the highest pushable rq's task, which is suitable to be executed
|
|
* on the cpu, NULL otherwise
|
|
*/
|
|
static struct task_struct *pick_highest_pushable_task(struct rq *rq, int cpu)
|
|
{
|
|
struct plist_head *head = &rq->rt.pushable_tasks;
|
|
struct task_struct *p;
|
|
|
|
if (!has_pushable_tasks(rq))
|
|
return NULL;
|
|
|
|
plist_for_each_entry(p, head, pushable_tasks) {
|
|
if (pick_rt_task(rq, p, cpu))
|
|
return p;
|
|
}
|
|
|
|
return NULL;
|
|
}
|
|
|
|
static DEFINE_PER_CPU(cpumask_var_t, local_cpu_mask);
|
|
|
|
static int find_lowest_rq(struct task_struct *task)
|
|
{
|
|
struct sched_domain *sd;
|
|
struct cpumask *lowest_mask = this_cpu_cpumask_var_ptr(local_cpu_mask);
|
|
int this_cpu = smp_processor_id();
|
|
int cpu = task_cpu(task);
|
|
|
|
/* Make sure the mask is initialized first */
|
|
if (unlikely(!lowest_mask))
|
|
return -1;
|
|
|
|
if (tsk_nr_cpus_allowed(task) == 1)
|
|
return -1; /* No other targets possible */
|
|
|
|
if (!cpupri_find(&task_rq(task)->rd->cpupri, task, lowest_mask))
|
|
return -1; /* No targets found */
|
|
|
|
/*
|
|
* 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.
|
|
*/
|
|
if (cpumask_test_cpu(cpu, lowest_mask))
|
|
return cpu;
|
|
|
|
/*
|
|
* Otherwise, we consult the sched_domains span maps to figure
|
|
* out which cpu is logically closest to our hot cache data.
|
|
*/
|
|
if (!cpumask_test_cpu(this_cpu, lowest_mask))
|
|
this_cpu = -1; /* Skip this_cpu opt if not among lowest */
|
|
|
|
rcu_read_lock();
|
|
for_each_domain(cpu, sd) {
|
|
if (sd->flags & SD_WAKE_AFFINE) {
|
|
int best_cpu;
|
|
|
|
/*
|
|
* "this_cpu" is cheaper to preempt than a
|
|
* remote processor.
|
|
*/
|
|
if (this_cpu != -1 &&
|
|
cpumask_test_cpu(this_cpu, sched_domain_span(sd))) {
|
|
rcu_read_unlock();
|
|
return this_cpu;
|
|
}
|
|
|
|
best_cpu = cpumask_first_and(lowest_mask,
|
|
sched_domain_span(sd));
|
|
if (best_cpu < nr_cpu_ids) {
|
|
rcu_read_unlock();
|
|
return best_cpu;
|
|
}
|
|
}
|
|
}
|
|
rcu_read_unlock();
|
|
|
|
/*
|
|
* And finally, if there were no matches within the domains
|
|
* just give the caller *something* to work with from the compatible
|
|
* locations.
|
|
*/
|
|
if (this_cpu != -1)
|
|
return this_cpu;
|
|
|
|
cpu = cpumask_any(lowest_mask);
|
|
if (cpu < nr_cpu_ids)
|
|
return cpu;
|
|
return -1;
|
|
}
|
|
|
|
/* Will lock the rq it finds */
|
|
static struct rq *find_lock_lowest_rq(struct task_struct *task, struct rq *rq)
|
|
{
|
|
struct rq *lowest_rq = NULL;
|
|
int tries;
|
|
int cpu;
|
|
|
|
for (tries = 0; tries < RT_MAX_TRIES; tries++) {
|
|
cpu = find_lowest_rq(task);
|
|
|
|
if ((cpu == -1) || (cpu == rq->cpu))
|
|
break;
|
|
|
|
lowest_rq = cpu_rq(cpu);
|
|
|
|
if (lowest_rq->rt.highest_prio.curr <= task->prio) {
|
|
/*
|
|
* Target rq has tasks of equal or higher priority,
|
|
* retrying does not release any lock and is unlikely
|
|
* to yield a different result.
|
|
*/
|
|
lowest_rq = NULL;
|
|
break;
|
|
}
|
|
|
|
/* if the prio of this runqueue changed, try again */
|
|
if (double_lock_balance(rq, lowest_rq)) {
|
|
/*
|
|
* 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.
|
|
*/
|
|
if (unlikely(task_rq(task) != rq ||
|
|
!cpumask_test_cpu(lowest_rq->cpu,
|
|
tsk_cpus_allowed(task)) ||
|
|
task_running(rq, task) ||
|
|
!rt_task(task) ||
|
|
!task_on_rq_queued(task))) {
|
|
|
|
double_unlock_balance(rq, lowest_rq);
|
|
lowest_rq = NULL;
|
|
break;
|
|
}
|
|
}
|
|
|
|
/* If this rq is still suitable use it. */
|
|
if (lowest_rq->rt.highest_prio.curr > task->prio)
|
|
break;
|
|
|
|
/* try again */
|
|
double_unlock_balance(rq, lowest_rq);
|
|
lowest_rq = NULL;
|
|
}
|
|
|
|
return lowest_rq;
|
|
}
|
|
|
|
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));
|
|
BUG_ON(tsk_nr_cpus_allowed(p) <= 1);
|
|
|
|
BUG_ON(!task_on_rq_queued(p));
|
|
BUG_ON(!rt_task(p));
|
|
|
|
return p;
|
|
}
|
|
|
|
/*
|
|
* 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.
|
|
*/
|
|
static int push_rt_task(struct rq *rq)
|
|
{
|
|
struct task_struct *next_task;
|
|
struct rq *lowest_rq;
|
|
int ret = 0;
|
|
|
|
if (!rq->rt.overloaded)
|
|
return 0;
|
|
|
|
next_task = pick_next_pushable_task(rq);
|
|
if (!next_task)
|
|
return 0;
|
|
|
|
retry:
|
|
if (unlikely(next_task == rq->curr)) {
|
|
WARN_ON(1);
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* It's possible that the next_task slipped in of
|
|
* higher priority than current. If that's the case
|
|
* just reschedule current.
|
|
*/
|
|
if (unlikely(next_task->prio < rq->curr->prio)) {
|
|
resched_curr(rq);
|
|
return 0;
|
|
}
|
|
|
|
/* We might release rq lock */
|
|
get_task_struct(next_task);
|
|
|
|
/* find_lock_lowest_rq locks the rq if found */
|
|
lowest_rq = find_lock_lowest_rq(next_task, rq);
|
|
if (!lowest_rq) {
|
|
struct task_struct *task;
|
|
/*
|
|
* find_lock_lowest_rq releases rq->lock
|
|
* 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.
|
|
*/
|
|
task = pick_next_pushable_task(rq);
|
|
if (task_cpu(next_task) == rq->cpu && task == next_task) {
|
|
/*
|
|
* 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.
|
|
*/
|
|
goto out;
|
|
}
|
|
|
|
if (!task)
|
|
/* No more tasks, just exit */
|
|
goto out;
|
|
|
|
/*
|
|
* Something has shifted, try again.
|
|
*/
|
|
put_task_struct(next_task);
|
|
next_task = task;
|
|
goto retry;
|
|
}
|
|
|
|
deactivate_task(rq, next_task, 0);
|
|
set_task_cpu(next_task, lowest_rq->cpu);
|
|
activate_task(lowest_rq, next_task, 0);
|
|
ret = 1;
|
|
|
|
resched_curr(lowest_rq);
|
|
|
|
double_unlock_balance(rq, lowest_rq);
|
|
|
|
out:
|
|
put_task_struct(next_task);
|
|
|
|
return ret;
|
|
}
|
|
|
|
static void push_rt_tasks(struct rq *rq)
|
|
{
|
|
/* push_rt_task will return true if it moved an RT */
|
|
while (push_rt_task(rq))
|
|
;
|
|
}
|
|
|
|
#ifdef HAVE_RT_PUSH_IPI
|
|
/*
|
|
* The search for the next cpu always starts at rq->cpu and ends
|
|
* when we reach rq->cpu again. It will never return rq->cpu.
|
|
* This returns the next cpu to check, or nr_cpu_ids if the loop
|
|
* is complete.
|
|
*
|
|
* rq->rt.push_cpu holds the last cpu returned by this function,
|
|
* or if this is the first instance, it must hold rq->cpu.
|
|
*/
|
|
static int rto_next_cpu(struct rq *rq)
|
|
{
|
|
int prev_cpu = rq->rt.push_cpu;
|
|
int cpu;
|
|
|
|
cpu = cpumask_next(prev_cpu, rq->rd->rto_mask);
|
|
|
|
/*
|
|
* If the previous cpu is less than the rq's CPU, then it already
|
|
* passed the end of the mask, and has started from the beginning.
|
|
* We end if the next CPU is greater or equal to rq's CPU.
|
|
*/
|
|
if (prev_cpu < rq->cpu) {
|
|
if (cpu >= rq->cpu)
|
|
return nr_cpu_ids;
|
|
|
|
} else if (cpu >= nr_cpu_ids) {
|
|
/*
|
|
* We passed the end of the mask, start at the beginning.
|
|
* If the result is greater or equal to the rq's CPU, then
|
|
* the loop is finished.
|
|
*/
|
|
cpu = cpumask_first(rq->rd->rto_mask);
|
|
if (cpu >= rq->cpu)
|
|
return nr_cpu_ids;
|
|
}
|
|
rq->rt.push_cpu = cpu;
|
|
|
|
/* Return cpu to let the caller know if the loop is finished or not */
|
|
return cpu;
|
|
}
|
|
|
|
static int find_next_push_cpu(struct rq *rq)
|
|
{
|
|
struct rq *next_rq;
|
|
int cpu;
|
|
|
|
while (1) {
|
|
cpu = rto_next_cpu(rq);
|
|
if (cpu >= nr_cpu_ids)
|
|
break;
|
|
next_rq = cpu_rq(cpu);
|
|
|
|
/* Make sure the next rq can push to this rq */
|
|
if (next_rq->rt.highest_prio.next < rq->rt.highest_prio.curr)
|
|
break;
|
|
}
|
|
|
|
return cpu;
|
|
}
|
|
|
|
#define RT_PUSH_IPI_EXECUTING 1
|
|
#define RT_PUSH_IPI_RESTART 2
|
|
|
|
static void tell_cpu_to_push(struct rq *rq)
|
|
{
|
|
int cpu;
|
|
|
|
if (rq->rt.push_flags & RT_PUSH_IPI_EXECUTING) {
|
|
raw_spin_lock(&rq->rt.push_lock);
|
|
/* Make sure it's still executing */
|
|
if (rq->rt.push_flags & RT_PUSH_IPI_EXECUTING) {
|
|
/*
|
|
* Tell the IPI to restart the loop as things have
|
|
* changed since it started.
|
|
*/
|
|
rq->rt.push_flags |= RT_PUSH_IPI_RESTART;
|
|
raw_spin_unlock(&rq->rt.push_lock);
|
|
return;
|
|
}
|
|
raw_spin_unlock(&rq->rt.push_lock);
|
|
}
|
|
|
|
/* When here, there's no IPI going around */
|
|
|
|
rq->rt.push_cpu = rq->cpu;
|
|
cpu = find_next_push_cpu(rq);
|
|
if (cpu >= nr_cpu_ids)
|
|
return;
|
|
|
|
rq->rt.push_flags = RT_PUSH_IPI_EXECUTING;
|
|
|
|
irq_work_queue_on(&rq->rt.push_work, cpu);
|
|
}
|
|
|
|
/* Called from hardirq context */
|
|
static void try_to_push_tasks(void *arg)
|
|
{
|
|
struct rt_rq *rt_rq = arg;
|
|
struct rq *rq, *src_rq;
|
|
int this_cpu;
|
|
int cpu;
|
|
|
|
this_cpu = rt_rq->push_cpu;
|
|
|
|
/* Paranoid check */
|
|
BUG_ON(this_cpu != smp_processor_id());
|
|
|
|
rq = cpu_rq(this_cpu);
|
|
src_rq = rq_of_rt_rq(rt_rq);
|
|
|
|
again:
|
|
if (has_pushable_tasks(rq)) {
|
|
raw_spin_lock(&rq->lock);
|
|
push_rt_task(rq);
|
|
raw_spin_unlock(&rq->lock);
|
|
}
|
|
|
|
/* Pass the IPI to the next rt overloaded queue */
|
|
raw_spin_lock(&rt_rq->push_lock);
|
|
/*
|
|
* If the source queue changed since the IPI went out,
|
|
* we need to restart the search from that CPU again.
|
|
*/
|
|
if (rt_rq->push_flags & RT_PUSH_IPI_RESTART) {
|
|
rt_rq->push_flags &= ~RT_PUSH_IPI_RESTART;
|
|
rt_rq->push_cpu = src_rq->cpu;
|
|
}
|
|
|
|
cpu = find_next_push_cpu(src_rq);
|
|
|
|
if (cpu >= nr_cpu_ids)
|
|
rt_rq->push_flags &= ~RT_PUSH_IPI_EXECUTING;
|
|
raw_spin_unlock(&rt_rq->push_lock);
|
|
|
|
if (cpu >= nr_cpu_ids)
|
|
return;
|
|
|
|
/*
|
|
* It is possible that a restart caused this CPU to be
|
|
* chosen again. Don't bother with an IPI, just see if we
|
|
* have more to push.
|
|
*/
|
|
if (unlikely(cpu == rq->cpu))
|
|
goto again;
|
|
|
|
/* Try the next RT overloaded CPU */
|
|
irq_work_queue_on(&rt_rq->push_work, cpu);
|
|
}
|
|
|
|
static void push_irq_work_func(struct irq_work *work)
|
|
{
|
|
struct rt_rq *rt_rq = container_of(work, struct rt_rq, push_work);
|
|
|
|
try_to_push_tasks(rt_rq);
|
|
}
|
|
#endif /* HAVE_RT_PUSH_IPI */
|
|
|
|
static void pull_rt_task(struct rq *this_rq)
|
|
{
|
|
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;
|
|
|
|
/*
|
|
* Match the barrier from rt_set_overloaded; this guarantees that if we
|
|
* see overloaded we must also see the rto_mask bit.
|
|
*/
|
|
smp_rmb();
|
|
|
|
#ifdef HAVE_RT_PUSH_IPI
|
|
if (sched_feat(RT_PUSH_IPI)) {
|
|
tell_cpu_to_push(this_rq);
|
|
return;
|
|
}
|
|
#endif
|
|
|
|
for_each_cpu(cpu, this_rq->rd->rto_mask) {
|
|
if (this_cpu == cpu)
|
|
continue;
|
|
|
|
src_rq = cpu_rq(cpu);
|
|
|
|
/*
|
|
* 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;
|
|
|
|
/*
|
|
* We can potentially drop this_rq's lock in
|
|
* double_lock_balance, and another CPU could
|
|
* alter this_rq
|
|
*/
|
|
double_lock_balance(this_rq, src_rq);
|
|
|
|
/*
|
|
* We can pull only a task, which is pushable
|
|
* on its rq, and no others.
|
|
*/
|
|
p = pick_highest_pushable_task(src_rq, this_cpu);
|
|
|
|
/*
|
|
* Do we have an RT task that preempts
|
|
* the to-be-scheduled task?
|
|
*/
|
|
if (p && (p->prio < this_rq->rt.highest_prio.curr)) {
|
|
WARN_ON(p == src_rq->curr);
|
|
WARN_ON(!task_on_rq_queued(p));
|
|
|
|
/*
|
|
* 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
|
|
* current task on the run queue
|
|
*/
|
|
if (p->prio < src_rq->curr->prio)
|
|
goto skip;
|
|
|
|
resched = true;
|
|
|
|
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
|
|
* in another runqueue. (low likelihood
|
|
* but possible)
|
|
*/
|
|
}
|
|
skip:
|
|
double_unlock_balance(this_rq, src_rq);
|
|
}
|
|
|
|
if (resched)
|
|
resched_curr(this_rq);
|
|
}
|
|
|
|
/*
|
|
* If we are not running and we are not going to reschedule soon, we should
|
|
* try to push tasks away now
|
|
*/
|
|
static void task_woken_rt(struct rq *rq, struct task_struct *p)
|
|
{
|
|
if (!task_running(rq, p) &&
|
|
!test_tsk_need_resched(rq->curr) &&
|
|
tsk_nr_cpus_allowed(p) > 1 &&
|
|
(dl_task(rq->curr) || rt_task(rq->curr)) &&
|
|
(tsk_nr_cpus_allowed(rq->curr) < 2 ||
|
|
rq->curr->prio <= p->prio))
|
|
push_rt_tasks(rq);
|
|
}
|
|
|
|
/* Assumes rq->lock is held */
|
|
static void rq_online_rt(struct rq *rq)
|
|
{
|
|
if (rq->rt.overloaded)
|
|
rt_set_overload(rq);
|
|
|
|
__enable_runtime(rq);
|
|
|
|
cpupri_set(&rq->rd->cpupri, rq->cpu, rq->rt.highest_prio.curr);
|
|
}
|
|
|
|
/* Assumes rq->lock is held */
|
|
static void rq_offline_rt(struct rq *rq)
|
|
{
|
|
if (rq->rt.overloaded)
|
|
rt_clear_overload(rq);
|
|
|
|
__disable_runtime(rq);
|
|
|
|
cpupri_set(&rq->rd->cpupri, rq->cpu, CPUPRI_INVALID);
|
|
}
|
|
|
|
/*
|
|
* When switch from the rt queue, we bring ourselves to a position
|
|
* that we might want to pull RT tasks from other runqueues.
|
|
*/
|
|
static void switched_from_rt(struct rq *rq, struct task_struct *p)
|
|
{
|
|
/*
|
|
* 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.
|
|
*/
|
|
if (!task_on_rq_queued(p) || rq->rt.rt_nr_running)
|
|
return;
|
|
|
|
queue_pull_task(rq);
|
|
}
|
|
|
|
void __init init_sched_rt_class(void)
|
|
{
|
|
unsigned int i;
|
|
|
|
for_each_possible_cpu(i) {
|
|
zalloc_cpumask_var_node(&per_cpu(local_cpu_mask, i),
|
|
GFP_KERNEL, cpu_to_node(i));
|
|
}
|
|
}
|
|
#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.
|
|
*/
|
|
static void switched_to_rt(struct rq *rq, struct task_struct *p)
|
|
{
|
|
/*
|
|
* 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.
|
|
*/
|
|
if (task_on_rq_queued(p) && rq->curr != p) {
|
|
#ifdef CONFIG_SMP
|
|
if (tsk_nr_cpus_allowed(p) > 1 && rq->rt.overloaded)
|
|
queue_push_tasks(rq);
|
|
#else
|
|
if (p->prio < rq->curr->prio)
|
|
resched_curr(rq);
|
|
#endif /* CONFIG_SMP */
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Priority of the task has changed. This may cause
|
|
* us to initiate a push or pull.
|
|
*/
|
|
static void
|
|
prio_changed_rt(struct rq *rq, struct task_struct *p, int oldprio)
|
|
{
|
|
if (!task_on_rq_queued(p))
|
|
return;
|
|
|
|
if (rq->curr == p) {
|
|
#ifdef CONFIG_SMP
|
|
/*
|
|
* If our priority decreases while running, we
|
|
* may need to pull tasks to this runqueue.
|
|
*/
|
|
if (oldprio < p->prio)
|
|
queue_pull_task(rq);
|
|
|
|
/*
|
|
* If there's a higher priority task waiting to run
|
|
* then reschedule.
|
|
*/
|
|
if (p->prio > rq->rt.highest_prio.curr)
|
|
resched_curr(rq);
|
|
#else
|
|
/* For UP simply resched on drop of prio */
|
|
if (oldprio < p->prio)
|
|
resched_curr(rq);
|
|
#endif /* CONFIG_SMP */
|
|
} 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_curr(rq);
|
|
}
|
|
}
|
|
|
|
static void watchdog(struct rq *rq, struct task_struct *p)
|
|
{
|
|
unsigned long soft, hard;
|
|
|
|
/* 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);
|
|
|
|
if (soft != RLIM_INFINITY) {
|
|
unsigned long next;
|
|
|
|
if (p->rt.watchdog_stamp != jiffies) {
|
|
p->rt.timeout++;
|
|
p->rt.watchdog_stamp = jiffies;
|
|
}
|
|
|
|
next = DIV_ROUND_UP(min(soft, hard), USEC_PER_SEC/HZ);
|
|
if (p->rt.timeout > next)
|
|
p->cputime_expires.sched_exp = p->se.sum_exec_runtime;
|
|
}
|
|
}
|
|
|
|
static void task_tick_rt(struct rq *rq, struct task_struct *p, int queued)
|
|
{
|
|
struct sched_rt_entity *rt_se = &p->rt;
|
|
|
|
update_curr_rt(rq);
|
|
|
|
watchdog(rq, p);
|
|
|
|
/*
|
|
* RR tasks need a special form of timeslice management.
|
|
* FIFO tasks have no timeslices.
|
|
*/
|
|
if (p->policy != SCHED_RR)
|
|
return;
|
|
|
|
if (--p->rt.time_slice)
|
|
return;
|
|
|
|
p->rt.time_slice = sched_rr_timeslice;
|
|
|
|
/*
|
|
* Requeue to the end of queue if we (and all of our ancestors) are not
|
|
* the only element on the queue
|
|
*/
|
|
for_each_sched_rt_entity(rt_se) {
|
|
if (rt_se->run_list.prev != rt_se->run_list.next) {
|
|
requeue_task_rt(rq, p, 0);
|
|
resched_curr(rq);
|
|
return;
|
|
}
|
|
}
|
|
}
|
|
|
|
static void set_curr_task_rt(struct rq *rq)
|
|
{
|
|
struct task_struct *p = rq->curr;
|
|
|
|
p->se.exec_start = rq_clock_task(rq);
|
|
|
|
/* The running task is never eligible for pushing */
|
|
dequeue_pushable_task(rq, p);
|
|
}
|
|
|
|
static unsigned int get_rr_interval_rt(struct rq *rq, struct task_struct *task)
|
|
{
|
|
/*
|
|
* Time slice is 0 for SCHED_FIFO tasks
|
|
*/
|
|
if (task->policy == SCHED_RR)
|
|
return sched_rr_timeslice;
|
|
else
|
|
return 0;
|
|
}
|
|
|
|
const struct sched_class rt_sched_class = {
|
|
.next = &fair_sched_class,
|
|
.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,
|
|
|
|
#ifdef CONFIG_SMP
|
|
.select_task_rq = select_task_rq_rt,
|
|
|
|
.set_cpus_allowed = set_cpus_allowed_common,
|
|
.rq_online = rq_online_rt,
|
|
.rq_offline = rq_offline_rt,
|
|
.task_woken = task_woken_rt,
|
|
.switched_from = switched_from_rt,
|
|
#endif
|
|
|
|
.set_curr_task = set_curr_task_rt,
|
|
.task_tick = task_tick_rt,
|
|
|
|
.get_rr_interval = get_rr_interval_rt,
|
|
|
|
.prio_changed = prio_changed_rt,
|
|
.switched_to = switched_to_rt,
|
|
|
|
.update_curr = update_curr_rt,
|
|
};
|
|
|
|
#ifdef CONFIG_SCHED_DEBUG
|
|
extern void print_rt_rq(struct seq_file *m, int cpu, struct rt_rq *rt_rq);
|
|
|
|
void print_rt_stats(struct seq_file *m, int cpu)
|
|
{
|
|
rt_rq_iter_t iter;
|
|
struct rt_rq *rt_rq;
|
|
|
|
rcu_read_lock();
|
|
for_each_rt_rq(rt_rq, iter, cpu_rq(cpu))
|
|
print_rt_rq(m, cpu, rt_rq);
|
|
rcu_read_unlock();
|
|
}
|
|
#endif /* CONFIG_SCHED_DEBUG */
|