| /* |
| * Real-Time Scheduling Class (mapped to the SCHED_FIFO and SCHED_RR |
| * policies) |
| */ |
| |
| #ifdef CONFIG_SMP |
| |
| static inline int rt_overloaded(struct rq *rq) |
| { |
| return atomic_read(&rq->rd->rto_count); |
| } |
| |
| static inline void rt_set_overload(struct rq *rq) |
| { |
| cpu_set(rq->cpu, rq->rd->rto_mask); |
| /* |
| * Make sure the mask is visible before we set |
| * the overload count. That is checked to determine |
| * if we should look at the mask. It would be a shame |
| * if we looked at the mask, but the mask was not |
| * updated yet. |
| */ |
| wmb(); |
| atomic_inc(&rq->rd->rto_count); |
| } |
| |
| static inline void rt_clear_overload(struct rq *rq) |
| { |
| /* the order here really doesn't matter */ |
| atomic_dec(&rq->rd->rto_count); |
| cpu_clear(rq->cpu, rq->rd->rto_mask); |
| } |
| |
| static void update_rt_migration(struct rq *rq) |
| { |
| if (rq->rt.rt_nr_migratory && (rq->rt.rt_nr_running > 1)) { |
| if (!rq->rt.overloaded) { |
| rt_set_overload(rq); |
| rq->rt.overloaded = 1; |
| } |
| } else if (rq->rt.overloaded) { |
| rt_clear_overload(rq); |
| rq->rt.overloaded = 0; |
| } |
| } |
| #endif /* CONFIG_SMP */ |
| |
| static inline struct task_struct *rt_task_of(struct sched_rt_entity *rt_se) |
| { |
| return container_of(rt_se, struct task_struct, rt); |
| } |
| |
| static inline int on_rt_rq(struct sched_rt_entity *rt_se) |
| { |
| return !list_empty(&rt_se->run_list); |
| } |
| |
| #ifdef CONFIG_RT_GROUP_SCHED |
| |
| static inline u64 sched_rt_runtime(struct rt_rq *rt_rq) |
| { |
| if (!rt_rq->tg) |
| return RUNTIME_INF; |
| |
| return rt_rq->rt_runtime; |
| } |
| |
| static inline u64 sched_rt_period(struct rt_rq *rt_rq) |
| { |
| return ktime_to_ns(rt_rq->tg->rt_bandwidth.rt_period); |
| } |
| |
| #define for_each_leaf_rt_rq(rt_rq, rq) \ |
| list_for_each_entry(rt_rq, &rq->leaf_rt_rq_list, leaf_rt_rq_list) |
| |
| static inline struct rq *rq_of_rt_rq(struct rt_rq *rt_rq) |
| { |
| return rt_rq->rq; |
| } |
| |
| static inline struct rt_rq *rt_rq_of_se(struct sched_rt_entity *rt_se) |
| { |
| return rt_se->rt_rq; |
| } |
| |
| #define for_each_sched_rt_entity(rt_se) \ |
| for (; rt_se; rt_se = rt_se->parent) |
| |
| static inline struct rt_rq *group_rt_rq(struct sched_rt_entity *rt_se) |
| { |
| return rt_se->my_q; |
| } |
| |
| static void enqueue_rt_entity(struct sched_rt_entity *rt_se); |
| static void dequeue_rt_entity(struct sched_rt_entity *rt_se); |
| |
| static void sched_rt_rq_enqueue(struct rt_rq *rt_rq) |
| { |
| struct sched_rt_entity *rt_se = rt_rq->rt_se; |
| |
| if (rt_se && !on_rt_rq(rt_se) && rt_rq->rt_nr_running) { |
| struct task_struct *curr = rq_of_rt_rq(rt_rq)->curr; |
| |
| enqueue_rt_entity(rt_se); |
| if (rt_rq->highest_prio < curr->prio) |
| resched_task(curr); |
| } |
| } |
| |
| static void sched_rt_rq_dequeue(struct rt_rq *rt_rq) |
| { |
| struct sched_rt_entity *rt_se = rt_rq->rt_se; |
| |
| if (rt_se && on_rt_rq(rt_se)) |
| dequeue_rt_entity(rt_se); |
| } |
| |
| 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 cpumask_t sched_rt_period_mask(void) |
| { |
| return cpu_rq(smp_processor_id())->rd->span; |
| } |
| #else |
| static inline cpumask_t sched_rt_period_mask(void) |
| { |
| return cpu_online_map; |
| } |
| #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 |
| |
| 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); |
| } |
| |
| #define for_each_leaf_rt_rq(rt_rq, rq) \ |
| for (rt_rq = &rq->rt; rt_rq; rt_rq = NULL) |
| |
| static inline struct rq *rq_of_rt_rq(struct rt_rq *rt_rq) |
| { |
| return container_of(rt_rq, struct rq, rt); |
| } |
| |
| static inline struct rt_rq *rt_rq_of_se(struct sched_rt_entity *rt_se) |
| { |
| struct task_struct *p = rt_task_of(rt_se); |
| struct rq *rq = task_rq(p); |
| |
| return &rq->rt; |
| } |
| |
| #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) |
| { |
| } |
| |
| static inline void sched_rt_rq_dequeue(struct rt_rq *rt_rq) |
| { |
| } |
| |
| static inline int rt_rq_throttled(struct rt_rq *rt_rq) |
| { |
| return rt_rq->rt_throttled; |
| } |
| |
| static inline cpumask_t sched_rt_period_mask(void) |
| { |
| return cpu_online_map; |
| } |
| |
| 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 |
| |
| static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun) |
| { |
| int i, idle = 1; |
| cpumask_t span; |
| |
| if (rt_b->rt_runtime == RUNTIME_INF) |
| return 1; |
| |
| span = sched_rt_period_mask(); |
| for_each_cpu_mask(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); |
| |
| spin_lock(&rq->lock); |
| if (rt_rq->rt_time) { |
| u64 runtime; |
| |
| spin_lock(&rt_rq->rt_runtime_lock); |
| 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; |
| } |
| if (rt_rq->rt_time || rt_rq->rt_nr_running) |
| idle = 0; |
| spin_unlock(&rt_rq->rt_runtime_lock); |
| } |
| |
| if (enqueue) |
| sched_rt_rq_enqueue(rt_rq); |
| spin_unlock(&rq->lock); |
| } |
| |
| return idle; |
| } |
| |
| #ifdef CONFIG_SMP |
| static int balance_runtime(struct rt_rq *rt_rq) |
| { |
| struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq); |
| struct root_domain *rd = cpu_rq(smp_processor_id())->rd; |
| int i, weight, more = 0; |
| u64 rt_period; |
| |
| weight = cpus_weight(rd->span); |
| |
| spin_lock(&rt_b->rt_runtime_lock); |
| rt_period = ktime_to_ns(rt_b->rt_period); |
| for_each_cpu_mask(i, rd->span) { |
| struct rt_rq *iter = sched_rt_period_rt_rq(rt_b, i); |
| s64 diff; |
| |
| if (iter == rt_rq) |
| continue; |
| |
| spin_lock(&iter->rt_runtime_lock); |
| diff = iter->rt_runtime - iter->rt_time; |
| if (diff > 0) { |
| do_div(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; |
| more = 1; |
| if (rt_rq->rt_runtime == rt_period) { |
| spin_unlock(&iter->rt_runtime_lock); |
| break; |
| } |
| } |
| spin_unlock(&iter->rt_runtime_lock); |
| } |
| spin_unlock(&rt_b->rt_runtime_lock); |
| |
| return more; |
| } |
| #endif |
| |
| 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; |
| #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 (runtime == RUNTIME_INF) |
| return 0; |
| |
| if (rt_rq->rt_throttled) |
| return rt_rq_throttled(rt_rq); |
| |
| if (sched_rt_runtime(rt_rq) >= sched_rt_period(rt_rq)) |
| return 0; |
| |
| #ifdef CONFIG_SMP |
| if (rt_rq->rt_time > runtime) { |
| int more; |
| |
| spin_unlock(&rt_rq->rt_runtime_lock); |
| more = balance_runtime(rt_rq); |
| spin_lock(&rt_rq->rt_runtime_lock); |
| |
| if (more) |
| runtime = sched_rt_runtime(rt_rq); |
| } |
| #endif |
| |
| if (rt_rq->rt_time > runtime) { |
| rt_rq->rt_throttled = 1; |
| 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; |
| struct rt_rq *rt_rq = rt_rq_of_se(rt_se); |
| u64 delta_exec; |
| |
| if (!task_has_rt_policy(curr)) |
| return; |
| |
| delta_exec = rq->clock - curr->se.exec_start; |
| if (unlikely((s64)delta_exec < 0)) |
| delta_exec = 0; |
| |
| schedstat_set(curr->se.exec_max, max(curr->se.exec_max, delta_exec)); |
| |
| curr->se.sum_exec_runtime += delta_exec; |
| curr->se.exec_start = rq->clock; |
| cpuacct_charge(curr, delta_exec); |
| |
| for_each_sched_rt_entity(rt_se) { |
| rt_rq = rt_rq_of_se(rt_se); |
| |
| spin_lock(&rt_rq->rt_runtime_lock); |
| rt_rq->rt_time += delta_exec; |
| if (sched_rt_runtime_exceeded(rt_rq)) |
| resched_task(curr); |
| spin_unlock(&rt_rq->rt_runtime_lock); |
| } |
| } |
| |
| static inline |
| void inc_rt_tasks(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq) |
| { |
| WARN_ON(!rt_prio(rt_se_prio(rt_se))); |
| rt_rq->rt_nr_running++; |
| #if defined CONFIG_SMP || defined CONFIG_RT_GROUP_SCHED |
| if (rt_se_prio(rt_se) < rt_rq->highest_prio) |
| rt_rq->highest_prio = rt_se_prio(rt_se); |
| #endif |
| #ifdef CONFIG_SMP |
| if (rt_se->nr_cpus_allowed > 1) { |
| struct rq *rq = rq_of_rt_rq(rt_rq); |
| rq->rt.rt_nr_migratory++; |
| } |
| |
| update_rt_migration(rq_of_rt_rq(rt_rq)); |
| #endif |
| #ifdef CONFIG_RT_GROUP_SCHED |
| if (rt_se_boosted(rt_se)) |
| rt_rq->rt_nr_boosted++; |
| |
| if (rt_rq->tg) |
| start_rt_bandwidth(&rt_rq->tg->rt_bandwidth); |
| #else |
| start_rt_bandwidth(&def_rt_bandwidth); |
| #endif |
| } |
| |
| 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--; |
| #if defined CONFIG_SMP || defined CONFIG_RT_GROUP_SCHED |
| if (rt_rq->rt_nr_running) { |
| struct rt_prio_array *array; |
| |
| WARN_ON(rt_se_prio(rt_se) < rt_rq->highest_prio); |
| if (rt_se_prio(rt_se) == rt_rq->highest_prio) { |
| /* recalculate */ |
| array = &rt_rq->active; |
| rt_rq->highest_prio = |
| sched_find_first_bit(array->bitmap); |
| } /* otherwise leave rq->highest prio alone */ |
| } else |
| rt_rq->highest_prio = MAX_RT_PRIO; |
| #endif |
| #ifdef CONFIG_SMP |
| if (rt_se->nr_cpus_allowed > 1) { |
| struct rq *rq = rq_of_rt_rq(rt_rq); |
| rq->rt.rt_nr_migratory--; |
| } |
| |
| update_rt_migration(rq_of_rt_rq(rt_rq)); |
| #endif /* CONFIG_SMP */ |
| #ifdef CONFIG_RT_GROUP_SCHED |
| if (rt_se_boosted(rt_se)) |
| rt_rq->rt_nr_boosted--; |
| |
| WARN_ON(!rt_rq->rt_nr_running && rt_rq->rt_nr_boosted); |
| #endif |
| } |
| |
| static void enqueue_rt_entity(struct sched_rt_entity *rt_se) |
| { |
| 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); |
| |
| if (group_rq && rt_rq_throttled(group_rq)) |
| return; |
| |
| list_add_tail(&rt_se->run_list, array->queue + rt_se_prio(rt_se)); |
| __set_bit(rt_se_prio(rt_se), array->bitmap); |
| |
| inc_rt_tasks(rt_se, rt_rq); |
| } |
| |
| static void dequeue_rt_entity(struct sched_rt_entity *rt_se) |
| { |
| struct rt_rq *rt_rq = rt_rq_of_se(rt_se); |
| struct rt_prio_array *array = &rt_rq->active; |
| |
| list_del_init(&rt_se->run_list); |
| if (list_empty(array->queue + rt_se_prio(rt_se))) |
| __clear_bit(rt_se_prio(rt_se), array->bitmap); |
| |
| dec_rt_tasks(rt_se, rt_rq); |
| } |
| |
| /* |
| * Because the prio of an upper entry depends on the lower |
| * entries, we must remove entries top - down. |
| * |
| * XXX: O(1/2 h^2) because we can only walk up, not down the chain. |
| */ |
| static void dequeue_rt_stack(struct task_struct *p) |
| { |
| struct sched_rt_entity *rt_se, *top_se; |
| |
| /* |
| * dequeue all, top - down. |
| */ |
| do { |
| rt_se = &p->rt; |
| top_se = NULL; |
| for_each_sched_rt_entity(rt_se) { |
| if (on_rt_rq(rt_se)) |
| top_se = rt_se; |
| } |
| if (top_se) |
| dequeue_rt_entity(top_se); |
| } while (top_se); |
| } |
| |
| /* |
| * Adding/removing a task to/from a priority array: |
| */ |
| static void enqueue_task_rt(struct rq *rq, struct task_struct *p, int wakeup) |
| { |
| struct sched_rt_entity *rt_se = &p->rt; |
| |
| if (wakeup) |
| rt_se->timeout = 0; |
| |
| dequeue_rt_stack(p); |
| |
| /* |
| * enqueue everybody, bottom - up. |
| */ |
| for_each_sched_rt_entity(rt_se) |
| enqueue_rt_entity(rt_se); |
| |
| inc_cpu_load(rq, p->se.load.weight); |
| } |
| |
| static void dequeue_task_rt(struct rq *rq, struct task_struct *p, int sleep) |
| { |
| struct sched_rt_entity *rt_se = &p->rt; |
| struct rt_rq *rt_rq; |
| |
| update_curr_rt(rq); |
| |
| dequeue_rt_stack(p); |
| |
| /* |
| * re-enqueue all non-empty rt_rq entities. |
| */ |
| for_each_sched_rt_entity(rt_se) { |
| rt_rq = group_rt_rq(rt_se); |
| if (rt_rq && rt_rq->rt_nr_running) |
| enqueue_rt_entity(rt_se); |
| } |
| |
| dec_cpu_load(rq, p->se.load.weight); |
| } |
| |
| /* |
| * Put task to 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) |
| { |
| struct rt_prio_array *array = &rt_rq->active; |
| |
| list_move_tail(&rt_se->run_list, array->queue + rt_se_prio(rt_se)); |
| } |
| |
| static void requeue_task_rt(struct rq *rq, struct task_struct *p) |
| { |
| 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); |
| } |
| } |
| |
| static void yield_task_rt(struct rq *rq) |
| { |
| requeue_task_rt(rq, rq->curr); |
| } |
| |
| #ifdef CONFIG_SMP |
| static int find_lowest_rq(struct task_struct *task); |
| |
| static int select_task_rq_rt(struct task_struct *p, int sync) |
| { |
| struct rq *rq = task_rq(p); |
| |
| /* |
| * If the current task 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. Even if |
| * the RT task is of higher priority than the current RT task. |
| * RT tasks behave differently than other tasks. If |
| * one gets preempted, we try to push it off to another queue. |
| * So trying to keep a preempting RT task on the same |
| * cache hot CPU will force the running RT task to |
| * a cold CPU. So we waste all the cache for the lower |
| * RT task in hopes of saving some of a RT task |
| * that is just being woken and probably will have |
| * cold cache anyway. |
| */ |
| if (unlikely(rt_task(rq->curr)) && |
| (p->rt.nr_cpus_allowed > 1)) { |
| int cpu = find_lowest_rq(p); |
| |
| return (cpu == -1) ? task_cpu(p) : cpu; |
| } |
| |
| /* |
| * Otherwise, just let it ride on the affined RQ and the |
| * post-schedule router will push the preempted task away |
| */ |
| return task_cpu(p); |
| } |
| #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) |
| { |
| if (p->prio < rq->curr->prio) |
| resched_task(rq->curr); |
| } |
| |
| 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; |
| |
| rt_rq = &rq->rt; |
| |
| if (unlikely(!rt_rq->rt_nr_running)) |
| return NULL; |
| |
| if (rt_rq_throttled(rt_rq)) |
| return NULL; |
| |
| 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; |
| return p; |
| } |
| |
| static void put_prev_task_rt(struct rq *rq, struct task_struct *p) |
| { |
| update_curr_rt(rq); |
| p->se.exec_start = 0; |
| } |
| |
| #ifdef CONFIG_SMP |
| |
| /* Only try algorithms three times */ |
| #define RT_MAX_TRIES 3 |
| |
| static int double_lock_balance(struct rq *this_rq, struct rq *busiest); |
| static void deactivate_task(struct rq *rq, struct task_struct *p, int sleep); |
| |
| static int pick_rt_task(struct rq *rq, struct task_struct *p, int cpu) |
| { |
| if (!task_running(rq, p) && |
| (cpu < 0 || cpu_isset(cpu, p->cpus_allowed)) && |
| (p->rt.nr_cpus_allowed > 1)) |
| return 1; |
| return 0; |
| } |
| |
| /* Return the second highest RT task, NULL otherwise */ |
| static struct task_struct *pick_next_highest_task_rt(struct rq *rq, int cpu) |
| { |
| struct task_struct *next = NULL; |
| struct sched_rt_entity *rt_se; |
| struct rt_prio_array *array; |
| struct rt_rq *rt_rq; |
| int idx; |
| |
| for_each_leaf_rt_rq(rt_rq, rq) { |
| array = &rt_rq->active; |
| idx = sched_find_first_bit(array->bitmap); |
| next_idx: |
| if (idx >= MAX_RT_PRIO) |
| continue; |
| if (next && next->prio < idx) |
| continue; |
| list_for_each_entry(rt_se, array->queue + idx, run_list) { |
| struct task_struct *p = rt_task_of(rt_se); |
| if (pick_rt_task(rq, p, cpu)) { |
| next = p; |
| break; |
| } |
| } |
| if (!next) { |
| idx = find_next_bit(array->bitmap, MAX_RT_PRIO, idx+1); |
| goto next_idx; |
| } |
| } |
| |
| return next; |
| } |
| |
| static DEFINE_PER_CPU(cpumask_t, local_cpu_mask); |
| |
| static int find_lowest_cpus(struct task_struct *task, cpumask_t *lowest_mask) |
| { |
| int lowest_prio = -1; |
| int lowest_cpu = -1; |
| int count = 0; |
| int cpu; |
| |
| cpus_and(*lowest_mask, task_rq(task)->rd->online, task->cpus_allowed); |
| |
| /* |
| * Scan each rq for the lowest prio. |
| */ |
| for_each_cpu_mask(cpu, *lowest_mask) { |
| struct rq *rq = cpu_rq(cpu); |
| |
| /* We look for lowest RT prio or non-rt CPU */ |
| if (rq->rt.highest_prio >= MAX_RT_PRIO) { |
| /* |
| * if we already found a low RT queue |
| * and now we found this non-rt queue |
| * clear the mask and set our bit. |
| * Otherwise just return the queue as is |
| * and the count==1 will cause the algorithm |
| * to use the first bit found. |
| */ |
| if (lowest_cpu != -1) { |
| cpus_clear(*lowest_mask); |
| cpu_set(rq->cpu, *lowest_mask); |
| } |
| return 1; |
| } |
| |
| /* no locking for now */ |
| if ((rq->rt.highest_prio > task->prio) |
| && (rq->rt.highest_prio >= lowest_prio)) { |
| if (rq->rt.highest_prio > lowest_prio) { |
| /* new low - clear old data */ |
| lowest_prio = rq->rt.highest_prio; |
| lowest_cpu = cpu; |
| count = 0; |
| } |
| count++; |
| } else |
| cpu_clear(cpu, *lowest_mask); |
| } |
| |
| /* |
| * Clear out all the set bits that represent |
| * runqueues that were of higher prio than |
| * the lowest_prio. |
| */ |
| if (lowest_cpu > 0) { |
| /* |
| * Perhaps we could add another cpumask op to |
| * zero out bits. Like cpu_zero_bits(cpumask, nrbits); |
| * Then that could be optimized to use memset and such. |
| */ |
| for_each_cpu_mask(cpu, *lowest_mask) { |
| if (cpu >= lowest_cpu) |
| break; |
| cpu_clear(cpu, *lowest_mask); |
| } |
| } |
| |
| return count; |
| } |
| |
| static inline int pick_optimal_cpu(int this_cpu, cpumask_t *mask) |
| { |
| int first; |
| |
| /* "this_cpu" is cheaper to preempt than a remote processor */ |
| if ((this_cpu != -1) && cpu_isset(this_cpu, *mask)) |
| return this_cpu; |
| |
| first = first_cpu(*mask); |
| if (first != NR_CPUS) |
| return first; |
| |
| return -1; |
| } |
| |
| static int find_lowest_rq(struct task_struct *task) |
| { |
| struct sched_domain *sd; |
| cpumask_t *lowest_mask = &__get_cpu_var(local_cpu_mask); |
| int this_cpu = smp_processor_id(); |
| int cpu = task_cpu(task); |
| int count = find_lowest_cpus(task, lowest_mask); |
| |
| if (!count) |
| return -1; /* No targets found */ |
| |
| /* |
| * There is no sense in performing an optimal search if only one |
| * target is found. |
| */ |
| if (count == 1) |
| return first_cpu(*lowest_mask); |
| |
| /* |
| * 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 (cpu_isset(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 (this_cpu == cpu) |
| this_cpu = -1; /* Skip this_cpu opt if the same */ |
| |
| for_each_domain(cpu, sd) { |
| if (sd->flags & SD_WAKE_AFFINE) { |
| cpumask_t domain_mask; |
| int best_cpu; |
| |
| cpus_and(domain_mask, sd->span, *lowest_mask); |
| |
| best_cpu = pick_optimal_cpu(this_cpu, |
| &domain_mask); |
| if (best_cpu != -1) |
| return best_cpu; |
| } |
| } |
| |
| /* |
| * And finally, if there were no matches within the domains |
| * just give the caller *something* to work with from the compatible |
| * locations. |
| */ |
| return pick_optimal_cpu(this_cpu, lowest_mask); |
| } |
| |
| /* 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 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 || |
| !cpu_isset(lowest_rq->cpu, |
| task->cpus_allowed) || |
| task_running(rq, task) || |
| !task->se.on_rq)) { |
| |
| spin_unlock(&lowest_rq->lock); |
| lowest_rq = NULL; |
| break; |
| } |
| } |
| |
| /* If this rq is still suitable use it. */ |
| if (lowest_rq->rt.highest_prio > task->prio) |
| break; |
| |
| /* try again */ |
| spin_unlock(&lowest_rq->lock); |
| lowest_rq = NULL; |
| } |
| |
| return lowest_rq; |
| } |
| |
| /* |
| * 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; |
| int paranoid = RT_MAX_TRIES; |
| |
| if (!rq->rt.overloaded) |
| return 0; |
| |
| next_task = pick_next_highest_task_rt(rq, -1); |
| 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_task(rq->curr); |
| 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 changed. |
| * 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) |
| goto skip; |
| |
| 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 skip; |
| |
| 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; |
| |
| } |
| skip: |
| 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, |
| const 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->rt.nr_cpus_allowed)) { |
| struct rq *rq = task_rq(p); |
| |
| if ((p->rt.nr_cpus_allowed <= 1) && (weight > 1)) { |
| rq->rt.rt_nr_migratory++; |
| } else if ((p->rt.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->rt.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. Note, the above pull_rt_task |
| * can release the rq lock and p could migrate. |
| * Only reschedule if p is still on the same runqueue. |
| */ |
| if (p->prio > rq->rt.highest_prio && rq->curr == p) |
| 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 watchdog(struct rq *rq, struct task_struct *p) |
| { |
| unsigned long soft, hard; |
| |
| if (!p->signal) |
| return; |
| |
| soft = p->signal->rlim[RLIMIT_RTTIME].rlim_cur; |
| hard = p->signal->rlim[RLIMIT_RTTIME].rlim_max; |
| |
| if (soft != RLIM_INFINITY) { |
| unsigned long next; |
| |
| p->rt.timeout++; |
| next = DIV_ROUND_UP(min(soft, hard), USEC_PER_SEC/HZ); |
| if (p->rt.timeout > next) |
| p->it_sched_expires = p->se.sum_exec_runtime; |
| } |
| } |
| |
| static void task_tick_rt(struct rq *rq, struct task_struct *p, int queued) |
| { |
| 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 = 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, |
| }; |