forked from luck/tmp_suning_uos_patched
fa717060f1
Move the task_struct members specific to rt scheduling together. A future optimization could be to put sched_entity and sched_rt_entity into a union. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> CC: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
903 lines
21 KiB
C
903 lines
21 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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#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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{
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cpu_set(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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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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/* the order here really doesn't matter */
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atomic_dec(&rq->rd->rto_count);
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cpu_clear(rq->cpu, rq->rd->rto_mask);
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}
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static void update_rt_migration(struct rq *rq)
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{
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if (rq->rt.rt_nr_migratory && (rq->rt.rt_nr_running > 1)) {
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if (!rq->rt.overloaded) {
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rt_set_overload(rq);
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rq->rt.overloaded = 1;
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}
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} else if (rq->rt.overloaded) {
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rt_clear_overload(rq);
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rq->rt.overloaded = 0;
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}
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}
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#endif /* CONFIG_SMP */
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/*
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* Update the current task's runtime statistics. Skip current tasks that
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* are not in our scheduling class.
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*/
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static void update_curr_rt(struct rq *rq)
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{
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struct task_struct *curr = rq->curr;
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u64 delta_exec;
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if (!task_has_rt_policy(curr))
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return;
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delta_exec = rq->clock - curr->se.exec_start;
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if (unlikely((s64)delta_exec < 0))
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delta_exec = 0;
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schedstat_set(curr->se.exec_max, max(curr->se.exec_max, delta_exec));
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curr->se.sum_exec_runtime += delta_exec;
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curr->se.exec_start = rq->clock;
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cpuacct_charge(curr, delta_exec);
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}
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static inline void inc_rt_tasks(struct task_struct *p, struct rq *rq)
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{
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WARN_ON(!rt_task(p));
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rq->rt.rt_nr_running++;
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#ifdef CONFIG_SMP
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if (p->prio < rq->rt.highest_prio)
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rq->rt.highest_prio = p->prio;
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if (p->nr_cpus_allowed > 1)
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rq->rt.rt_nr_migratory++;
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update_rt_migration(rq);
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#endif /* CONFIG_SMP */
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}
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static inline void dec_rt_tasks(struct task_struct *p, struct rq *rq)
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{
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WARN_ON(!rt_task(p));
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WARN_ON(!rq->rt.rt_nr_running);
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rq->rt.rt_nr_running--;
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#ifdef CONFIG_SMP
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if (rq->rt.rt_nr_running) {
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struct rt_prio_array *array;
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WARN_ON(p->prio < rq->rt.highest_prio);
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if (p->prio == rq->rt.highest_prio) {
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/* recalculate */
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array = &rq->rt.active;
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rq->rt.highest_prio =
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sched_find_first_bit(array->bitmap);
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} /* otherwise leave rq->highest prio alone */
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} else
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rq->rt.highest_prio = MAX_RT_PRIO;
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if (p->nr_cpus_allowed > 1)
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rq->rt.rt_nr_migratory--;
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update_rt_migration(rq);
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#endif /* CONFIG_SMP */
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}
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static void enqueue_task_rt(struct rq *rq, struct task_struct *p, int wakeup)
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{
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struct rt_prio_array *array = &rq->rt.active;
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list_add_tail(&p->rt.run_list, array->queue + p->prio);
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__set_bit(p->prio, array->bitmap);
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inc_cpu_load(rq, p->se.load.weight);
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inc_rt_tasks(p, rq);
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}
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/*
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* Adding/removing a task to/from a priority array:
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*/
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static void dequeue_task_rt(struct rq *rq, struct task_struct *p, int sleep)
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{
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struct rt_prio_array *array = &rq->rt.active;
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update_curr_rt(rq);
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list_del(&p->rt.run_list);
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if (list_empty(array->queue + p->prio))
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__clear_bit(p->prio, array->bitmap);
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dec_cpu_load(rq, p->se.load.weight);
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dec_rt_tasks(p, rq);
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}
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/*
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* Put task to the end of the run list without the overhead of dequeue
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* followed by enqueue.
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*/
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static void requeue_task_rt(struct rq *rq, struct task_struct *p)
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{
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struct rt_prio_array *array = &rq->rt.active;
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list_move_tail(&p->rt.run_list, array->queue + p->prio);
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}
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static void
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yield_task_rt(struct rq *rq)
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{
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requeue_task_rt(rq, rq->curr);
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}
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#ifdef CONFIG_SMP
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static int find_lowest_rq(struct task_struct *task);
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static int select_task_rq_rt(struct task_struct *p, int sync)
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{
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struct rq *rq = task_rq(p);
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/*
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* If the current task is an RT task, then
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* try to see if we can wake this RT task up on another
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* runqueue. Otherwise simply start this RT task
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* on its current runqueue.
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*
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* We want to avoid overloading runqueues. Even if
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* the RT task is of higher priority than the current RT task.
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* RT tasks behave differently than other tasks. If
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* one gets preempted, we try to push it off to another queue.
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* So trying to keep a preempting RT task on the same
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* cache hot CPU will force the running RT task to
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* a cold CPU. So we waste all the cache for the lower
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* RT task in hopes of saving some of a RT task
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* that is just being woken and probably will have
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* cold cache anyway.
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*/
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if (unlikely(rt_task(rq->curr)) &&
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(p->nr_cpus_allowed > 1)) {
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int cpu = find_lowest_rq(p);
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return (cpu == -1) ? task_cpu(p) : cpu;
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}
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/*
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* Otherwise, just let it ride on the affined RQ and the
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* post-schedule router will push the preempted task away
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*/
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return task_cpu(p);
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}
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#endif /* CONFIG_SMP */
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/*
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* Preempt the current task with a newly woken task if needed:
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*/
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static void check_preempt_curr_rt(struct rq *rq, struct task_struct *p)
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{
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if (p->prio < rq->curr->prio)
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resched_task(rq->curr);
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}
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static struct task_struct *pick_next_task_rt(struct rq *rq)
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{
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struct rt_prio_array *array = &rq->rt.active;
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struct task_struct *next;
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struct list_head *queue;
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int idx;
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idx = sched_find_first_bit(array->bitmap);
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if (idx >= MAX_RT_PRIO)
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return NULL;
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queue = array->queue + idx;
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next = list_entry(queue->next, struct task_struct, rt.run_list);
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next->se.exec_start = rq->clock;
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return next;
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}
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static void put_prev_task_rt(struct rq *rq, struct task_struct *p)
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{
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update_curr_rt(rq);
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p->se.exec_start = 0;
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}
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#ifdef CONFIG_SMP
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/* Only try algorithms three times */
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#define RT_MAX_TRIES 3
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static int double_lock_balance(struct rq *this_rq, struct rq *busiest);
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static void deactivate_task(struct rq *rq, struct task_struct *p, int sleep);
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static int pick_rt_task(struct rq *rq, struct task_struct *p, int cpu)
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{
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if (!task_running(rq, p) &&
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(cpu < 0 || cpu_isset(cpu, p->cpus_allowed)) &&
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(p->nr_cpus_allowed > 1))
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return 1;
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return 0;
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}
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/* Return the second highest RT task, NULL otherwise */
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static struct task_struct *pick_next_highest_task_rt(struct rq *rq, int cpu)
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{
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struct rt_prio_array *array = &rq->rt.active;
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struct task_struct *next;
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struct list_head *queue;
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int idx;
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if (likely(rq->rt.rt_nr_running < 2))
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return NULL;
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idx = sched_find_first_bit(array->bitmap);
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if (unlikely(idx >= MAX_RT_PRIO)) {
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WARN_ON(1); /* rt_nr_running is bad */
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return NULL;
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}
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queue = array->queue + idx;
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BUG_ON(list_empty(queue));
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next = list_entry(queue->next, struct task_struct, rt.run_list);
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if (unlikely(pick_rt_task(rq, next, cpu)))
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goto out;
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if (queue->next->next != queue) {
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/* same prio task */
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next = list_entry(queue->next->next, struct task_struct,
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rt.run_list);
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if (pick_rt_task(rq, next, cpu))
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goto out;
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}
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retry:
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/* slower, but more flexible */
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idx = find_next_bit(array->bitmap, MAX_RT_PRIO, idx+1);
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if (unlikely(idx >= MAX_RT_PRIO))
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return NULL;
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queue = array->queue + idx;
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BUG_ON(list_empty(queue));
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list_for_each_entry(next, queue, rt.run_list) {
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if (pick_rt_task(rq, next, cpu))
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goto out;
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}
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goto retry;
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out:
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return next;
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}
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static DEFINE_PER_CPU(cpumask_t, local_cpu_mask);
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static int find_lowest_cpus(struct task_struct *task, cpumask_t *lowest_mask)
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{
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int lowest_prio = -1;
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int lowest_cpu = -1;
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int count = 0;
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int cpu;
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cpus_and(*lowest_mask, task_rq(task)->rd->online, task->cpus_allowed);
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/*
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* Scan each rq for the lowest prio.
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*/
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for_each_cpu_mask(cpu, *lowest_mask) {
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struct rq *rq = cpu_rq(cpu);
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/* We look for lowest RT prio or non-rt CPU */
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if (rq->rt.highest_prio >= MAX_RT_PRIO) {
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/*
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* if we already found a low RT queue
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* and now we found this non-rt queue
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* clear the mask and set our bit.
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* Otherwise just return the queue as is
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* and the count==1 will cause the algorithm
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* to use the first bit found.
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*/
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if (lowest_cpu != -1) {
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cpus_clear(*lowest_mask);
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cpu_set(rq->cpu, *lowest_mask);
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}
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return 1;
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}
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/* no locking for now */
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if ((rq->rt.highest_prio > task->prio)
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&& (rq->rt.highest_prio >= lowest_prio)) {
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if (rq->rt.highest_prio > lowest_prio) {
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/* new low - clear old data */
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lowest_prio = rq->rt.highest_prio;
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lowest_cpu = cpu;
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count = 0;
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}
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count++;
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} else
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cpu_clear(cpu, *lowest_mask);
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}
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/*
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* Clear out all the set bits that represent
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* runqueues that were of higher prio than
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* the lowest_prio.
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*/
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if (lowest_cpu > 0) {
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/*
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* Perhaps we could add another cpumask op to
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* zero out bits. Like cpu_zero_bits(cpumask, nrbits);
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* Then that could be optimized to use memset and such.
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*/
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for_each_cpu_mask(cpu, *lowest_mask) {
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if (cpu >= lowest_cpu)
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break;
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cpu_clear(cpu, *lowest_mask);
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}
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}
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return count;
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}
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static inline int pick_optimal_cpu(int this_cpu, cpumask_t *mask)
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{
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int first;
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/* "this_cpu" is cheaper to preempt than a remote processor */
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if ((this_cpu != -1) && cpu_isset(this_cpu, *mask))
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return this_cpu;
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first = first_cpu(*mask);
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if (first != NR_CPUS)
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return first;
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return -1;
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}
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static int find_lowest_rq(struct task_struct *task)
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{
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struct sched_domain *sd;
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cpumask_t *lowest_mask = &__get_cpu_var(local_cpu_mask);
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int this_cpu = smp_processor_id();
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int cpu = task_cpu(task);
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int count = find_lowest_cpus(task, lowest_mask);
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if (!count)
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return -1; /* No targets found */
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/*
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* There is no sense in performing an optimal search if only one
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* target is found.
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*/
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if (count == 1)
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return first_cpu(*lowest_mask);
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/*
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* At this point we have built a mask of cpus representing the
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* lowest priority tasks in the system. Now we want to elect
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* the best one based on our affinity and topology.
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*
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* We prioritize the last cpu that the task executed on since
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* it is most likely cache-hot in that location.
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*/
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if (cpu_isset(cpu, *lowest_mask))
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return cpu;
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/*
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* Otherwise, we consult the sched_domains span maps to figure
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* out which cpu is logically closest to our hot cache data.
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*/
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if (this_cpu == cpu)
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this_cpu = -1; /* Skip this_cpu opt if the same */
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for_each_domain(cpu, sd) {
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if (sd->flags & SD_WAKE_AFFINE) {
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cpumask_t domain_mask;
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int best_cpu;
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cpus_and(domain_mask, sd->span, *lowest_mask);
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best_cpu = pick_optimal_cpu(this_cpu,
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&domain_mask);
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if (best_cpu != -1)
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return best_cpu;
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}
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}
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/*
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* And finally, if there were no matches within the domains
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* just give the caller *something* to work with from the compatible
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* locations.
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*/
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return pick_optimal_cpu(this_cpu, lowest_mask);
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}
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/* Will lock the rq it finds */
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static struct rq *find_lock_lowest_rq(struct task_struct *task, struct rq *rq)
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{
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struct rq *lowest_rq = NULL;
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int tries;
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int cpu;
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for (tries = 0; tries < RT_MAX_TRIES; tries++) {
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cpu = find_lowest_rq(task);
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if ((cpu == -1) || (cpu == rq->cpu))
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break;
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lowest_rq = cpu_rq(cpu);
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/* if the prio of this runqueue changed, try again */
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if (double_lock_balance(rq, lowest_rq)) {
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/*
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* We had to unlock the run queue. In
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* the mean time, task could have
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* migrated already or had its affinity changed.
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* Also make sure that it wasn't scheduled on its rq.
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*/
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if (unlikely(task_rq(task) != rq ||
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!cpu_isset(lowest_rq->cpu,
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task->cpus_allowed) ||
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task_running(rq, task) ||
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!task->se.on_rq)) {
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spin_unlock(&lowest_rq->lock);
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lowest_rq = NULL;
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break;
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}
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}
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/* If this rq is still suitable use it. */
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if (lowest_rq->rt.highest_prio > task->prio)
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break;
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/* try again */
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spin_unlock(&lowest_rq->lock);
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lowest_rq = NULL;
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}
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return lowest_rq;
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}
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/*
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* If the current CPU has more than one RT task, see if the non
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* running task can migrate over to a CPU that is running a task
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* of lesser priority.
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*/
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static int push_rt_task(struct rq *rq)
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{
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struct task_struct *next_task;
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struct rq *lowest_rq;
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int ret = 0;
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int paranoid = RT_MAX_TRIES;
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if (!rq->rt.overloaded)
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return 0;
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next_task = pick_next_highest_task_rt(rq, -1);
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if (!next_task)
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return 0;
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retry:
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if (unlikely(next_task == rq->curr)) {
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WARN_ON(1);
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return 0;
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}
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/*
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* It's possible that the next_task slipped in of
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* higher priority than current. If that's the case
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* just reschedule current.
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*/
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if (unlikely(next_task->prio < rq->curr->prio)) {
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resched_task(rq->curr);
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return 0;
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}
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/* We might release rq lock */
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get_task_struct(next_task);
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/* find_lock_lowest_rq locks the rq if found */
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lowest_rq = find_lock_lowest_rq(next_task, rq);
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if (!lowest_rq) {
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struct task_struct *task;
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/*
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* find lock_lowest_rq releases rq->lock
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* so it is possible that next_task has changed.
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* If it has, then try again.
|
|
*/
|
|
task = pick_next_highest_task_rt(rq, -1);
|
|
if (unlikely(task != next_task) && task && paranoid--) {
|
|
put_task_struct(next_task);
|
|
next_task = task;
|
|
goto retry;
|
|
}
|
|
goto out;
|
|
}
|
|
|
|
deactivate_task(rq, next_task, 0);
|
|
set_task_cpu(next_task, lowest_rq->cpu);
|
|
activate_task(lowest_rq, next_task, 0);
|
|
|
|
resched_task(lowest_rq->curr);
|
|
|
|
spin_unlock(&lowest_rq->lock);
|
|
|
|
ret = 1;
|
|
out:
|
|
put_task_struct(next_task);
|
|
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* TODO: Currently we just use the second highest prio task on
|
|
* the queue, and stop when it can't migrate (or there's
|
|
* no more RT tasks). There may be a case where a lower
|
|
* priority RT task has a different affinity than the
|
|
* higher RT task. In this case the lower RT task could
|
|
* possibly be able to migrate where as the higher priority
|
|
* RT task could not. We currently ignore this issue.
|
|
* Enhancements are welcome!
|
|
*/
|
|
static void push_rt_tasks(struct rq *rq)
|
|
{
|
|
/* push_rt_task will return true if it moved an RT */
|
|
while (push_rt_task(rq))
|
|
;
|
|
}
|
|
|
|
static int pull_rt_task(struct rq *this_rq)
|
|
{
|
|
int this_cpu = this_rq->cpu, ret = 0, cpu;
|
|
struct task_struct *p, *next;
|
|
struct rq *src_rq;
|
|
|
|
if (likely(!rt_overloaded(this_rq)))
|
|
return 0;
|
|
|
|
next = pick_next_task_rt(this_rq);
|
|
|
|
for_each_cpu_mask(cpu, this_rq->rd->rto_mask) {
|
|
if (this_cpu == cpu)
|
|
continue;
|
|
|
|
src_rq = cpu_rq(cpu);
|
|
/*
|
|
* We can potentially drop this_rq's lock in
|
|
* double_lock_balance, and another CPU could
|
|
* steal our next task - hence we must cause
|
|
* the caller to recalculate the next task
|
|
* in that case:
|
|
*/
|
|
if (double_lock_balance(this_rq, src_rq)) {
|
|
struct task_struct *old_next = next;
|
|
|
|
next = pick_next_task_rt(this_rq);
|
|
if (next != old_next)
|
|
ret = 1;
|
|
}
|
|
|
|
/*
|
|
* Are there still pullable RT tasks?
|
|
*/
|
|
if (src_rq->rt.rt_nr_running <= 1) {
|
|
spin_unlock(&src_rq->lock);
|
|
continue;
|
|
}
|
|
|
|
p = pick_next_highest_task_rt(src_rq, this_cpu);
|
|
|
|
/*
|
|
* Do we have an RT task that preempts
|
|
* the to-be-scheduled task?
|
|
*/
|
|
if (p && (!next || (p->prio < next->prio))) {
|
|
WARN_ON(p == src_rq->curr);
|
|
WARN_ON(!p->se.on_rq);
|
|
|
|
/*
|
|
* 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 or
|
|
* this_rq next task is lower in prio than
|
|
* the current task on that rq.
|
|
*/
|
|
if (p->prio < src_rq->curr->prio ||
|
|
(next && next->prio < src_rq->curr->prio))
|
|
goto out;
|
|
|
|
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
|
|
* in another runqueue. (low likelyhood
|
|
* but possible)
|
|
*
|
|
* Update next so that we won't pick a task
|
|
* on another cpu with a priority lower (or equal)
|
|
* than the one we just picked.
|
|
*/
|
|
next = p;
|
|
|
|
}
|
|
out:
|
|
spin_unlock(&src_rq->lock);
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
|
|
static void pre_schedule_rt(struct rq *rq, struct task_struct *prev)
|
|
{
|
|
/* Try to pull RT tasks here if we lower this rq's prio */
|
|
if (unlikely(rt_task(prev)) && rq->rt.highest_prio > prev->prio)
|
|
pull_rt_task(rq);
|
|
}
|
|
|
|
static void post_schedule_rt(struct rq *rq)
|
|
{
|
|
/*
|
|
* If we have more than one rt_task queued, then
|
|
* see if we can push the other rt_tasks off to other CPUS.
|
|
* Note we may release the rq lock, and since
|
|
* the lock was owned by prev, we need to release it
|
|
* first via finish_lock_switch and then reaquire it here.
|
|
*/
|
|
if (unlikely(rq->rt.overloaded)) {
|
|
spin_lock_irq(&rq->lock);
|
|
push_rt_tasks(rq);
|
|
spin_unlock_irq(&rq->lock);
|
|
}
|
|
}
|
|
|
|
|
|
static void task_wake_up_rt(struct rq *rq, struct task_struct *p)
|
|
{
|
|
if (!task_running(rq, p) &&
|
|
(p->prio >= rq->rt.highest_prio) &&
|
|
rq->rt.overloaded)
|
|
push_rt_tasks(rq);
|
|
}
|
|
|
|
static unsigned long
|
|
load_balance_rt(struct rq *this_rq, int this_cpu, struct rq *busiest,
|
|
unsigned long max_load_move,
|
|
struct sched_domain *sd, enum cpu_idle_type idle,
|
|
int *all_pinned, int *this_best_prio)
|
|
{
|
|
/* don't touch RT tasks */
|
|
return 0;
|
|
}
|
|
|
|
static int
|
|
move_one_task_rt(struct rq *this_rq, int this_cpu, struct rq *busiest,
|
|
struct sched_domain *sd, enum cpu_idle_type idle)
|
|
{
|
|
/* don't touch RT tasks */
|
|
return 0;
|
|
}
|
|
|
|
static void set_cpus_allowed_rt(struct task_struct *p, cpumask_t *new_mask)
|
|
{
|
|
int weight = cpus_weight(*new_mask);
|
|
|
|
BUG_ON(!rt_task(p));
|
|
|
|
/*
|
|
* Update the migration status of the RQ if we have an RT task
|
|
* which is running AND changing its weight value.
|
|
*/
|
|
if (p->se.on_rq && (weight != p->nr_cpus_allowed)) {
|
|
struct rq *rq = task_rq(p);
|
|
|
|
if ((p->nr_cpus_allowed <= 1) && (weight > 1)) {
|
|
rq->rt.rt_nr_migratory++;
|
|
} else if ((p->nr_cpus_allowed > 1) && (weight <= 1)) {
|
|
BUG_ON(!rq->rt.rt_nr_migratory);
|
|
rq->rt.rt_nr_migratory--;
|
|
}
|
|
|
|
update_rt_migration(rq);
|
|
}
|
|
|
|
p->cpus_allowed = *new_mask;
|
|
p->nr_cpus_allowed = weight;
|
|
}
|
|
|
|
/* Assumes rq->lock is held */
|
|
static void join_domain_rt(struct rq *rq)
|
|
{
|
|
if (rq->rt.overloaded)
|
|
rt_set_overload(rq);
|
|
}
|
|
|
|
/* Assumes rq->lock is held */
|
|
static void leave_domain_rt(struct rq *rq)
|
|
{
|
|
if (rq->rt.overloaded)
|
|
rt_clear_overload(rq);
|
|
}
|
|
|
|
/*
|
|
* 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,
|
|
int running)
|
|
{
|
|
/*
|
|
* 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 (!rq->rt.rt_nr_running)
|
|
pull_rt_task(rq);
|
|
}
|
|
#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,
|
|
int running)
|
|
{
|
|
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.
|
|
*/
|
|
if (!running) {
|
|
#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.
|
|
*/
|
|
static void prio_changed_rt(struct rq *rq, struct task_struct *p,
|
|
int oldprio, int running)
|
|
{
|
|
if (running) {
|
|
#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
|
|
* then reschedule.
|
|
*/
|
|
if (p->prio > rq->rt.highest_prio)
|
|
resched_task(p);
|
|
#else
|
|
/* For UP simply resched on drop of prio */
|
|
if (oldprio < p->prio)
|
|
resched_task(p);
|
|
#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_task(rq->curr);
|
|
}
|
|
}
|
|
|
|
|
|
static void task_tick_rt(struct rq *rq, struct task_struct *p)
|
|
{
|
|
update_curr_rt(rq);
|
|
|
|
/*
|
|
* 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 = DEF_TIMESLICE;
|
|
|
|
/*
|
|
* Requeue to the end of queue if we are not the only element
|
|
* on the queue:
|
|
*/
|
|
if (p->rt.run_list.prev != p->rt.run_list.next) {
|
|
requeue_task_rt(rq, p);
|
|
set_tsk_need_resched(p);
|
|
}
|
|
}
|
|
|
|
static void set_curr_task_rt(struct rq *rq)
|
|
{
|
|
struct task_struct *p = rq->curr;
|
|
|
|
p->se.exec_start = rq->clock;
|
|
}
|
|
|
|
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,
|
|
#ifdef CONFIG_SMP
|
|
.select_task_rq = select_task_rq_rt,
|
|
#endif /* CONFIG_SMP */
|
|
|
|
.check_preempt_curr = check_preempt_curr_rt,
|
|
|
|
.pick_next_task = pick_next_task_rt,
|
|
.put_prev_task = put_prev_task_rt,
|
|
|
|
#ifdef CONFIG_SMP
|
|
.load_balance = load_balance_rt,
|
|
.move_one_task = move_one_task_rt,
|
|
.set_cpus_allowed = set_cpus_allowed_rt,
|
|
.join_domain = join_domain_rt,
|
|
.leave_domain = leave_domain_rt,
|
|
.pre_schedule = pre_schedule_rt,
|
|
.post_schedule = post_schedule_rt,
|
|
.task_wake_up = task_wake_up_rt,
|
|
.switched_from = switched_from_rt,
|
|
#endif
|
|
|
|
.set_curr_task = set_curr_task_rt,
|
|
.task_tick = task_tick_rt,
|
|
|
|
.prio_changed = prio_changed_rt,
|
|
.switched_to = switched_to_rt,
|
|
};
|