diff options
Diffstat (limited to 'kernel/sched.c')
| -rw-r--r-- | kernel/sched.c | 157 |
1 files changed, 129 insertions, 28 deletions
diff --git a/kernel/sched.c b/kernel/sched.c index 3ce26954be12..ac3f5cc3bb51 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -206,6 +206,7 @@ struct runqueue { */ unsigned long nr_running; #ifdef CONFIG_SMP + unsigned long prio_bias; unsigned long cpu_load[3]; #endif unsigned long long nr_switches; @@ -659,13 +660,68 @@ static int effective_prio(task_t *p) return prio; } +#ifdef CONFIG_SMP +static inline void inc_prio_bias(runqueue_t *rq, int prio) +{ + rq->prio_bias += MAX_PRIO - prio; +} + +static inline void dec_prio_bias(runqueue_t *rq, int prio) +{ + rq->prio_bias -= MAX_PRIO - prio; +} + +static inline void inc_nr_running(task_t *p, runqueue_t *rq) +{ + rq->nr_running++; + if (rt_task(p)) { + if (p != rq->migration_thread) + /* + * The migration thread does the actual balancing. Do + * not bias by its priority as the ultra high priority + * will skew balancing adversely. + */ + inc_prio_bias(rq, p->prio); + } else + inc_prio_bias(rq, p->static_prio); +} + +static inline void dec_nr_running(task_t *p, runqueue_t *rq) +{ + rq->nr_running--; + if (rt_task(p)) { + if (p != rq->migration_thread) + dec_prio_bias(rq, p->prio); + } else + dec_prio_bias(rq, p->static_prio); +} +#else +static inline void inc_prio_bias(runqueue_t *rq, int prio) +{ +} + +static inline void dec_prio_bias(runqueue_t *rq, int prio) +{ +} + +static inline void inc_nr_running(task_t *p, runqueue_t *rq) +{ + rq->nr_running++; +} + +static inline void dec_nr_running(task_t *p, runqueue_t *rq) +{ + rq->nr_running--; +} +#endif + /* * __activate_task - move a task to the runqueue. */ static inline void __activate_task(task_t *p, runqueue_t *rq) { enqueue_task(p, rq->active); - rq->nr_running++; + inc_nr_running(p, rq); } /* @@ -674,7 +730,7 @@ static inline void __activate_task(task_t *p, runqueue_t *rq) static inline void __activate_idle_task(task_t *p, runqueue_t *rq) { enqueue_task_head(p, rq->active); - rq->nr_running++; + inc_nr_running(p, rq); } static int recalc_task_prio(task_t *p, unsigned long long now) @@ -793,7 +849,7 @@ static void activate_task(task_t *p, runqueue_t *rq, int local) */ static void deactivate_task(struct task_struct *p, runqueue_t *rq) { - rq->nr_running--; + dec_nr_running(p, rq); dequeue_task(p, p->array); p->array = NULL; } @@ -808,21 +864,28 @@ static void deactivate_task(struct task_struct *p, runqueue_t *rq) #ifdef CONFIG_SMP static void resched_task(task_t *p) { - int need_resched, nrpolling; + int cpu; assert_spin_locked(&task_rq(p)->lock); - /* minimise the chance of sending an interrupt to poll_idle() */ - nrpolling = test_tsk_thread_flag(p,TIF_POLLING_NRFLAG); - need_resched = test_and_set_tsk_thread_flag(p,TIF_NEED_RESCHED); - nrpolling |= test_tsk_thread_flag(p,TIF_POLLING_NRFLAG); + if (unlikely(test_tsk_thread_flag(p, TIF_NEED_RESCHED))) + return; + + set_tsk_thread_flag(p, TIF_NEED_RESCHED); + + cpu = task_cpu(p); + if (cpu == smp_processor_id()) + return; - if (!need_resched && !nrpolling && (task_cpu(p) != smp_processor_id())) - smp_send_reschedule(task_cpu(p)); + /* NEED_RESCHED must be visible before we test POLLING_NRFLAG */ + smp_mb(); + if (!test_tsk_thread_flag(p, TIF_POLLING_NRFLAG)) + smp_send_reschedule(cpu); } #else static inline void resched_task(task_t *p) { + assert_spin_locked(&task_rq(p)->lock); set_tsk_need_resched(p); } #endif @@ -930,27 +993,61 @@ void kick_process(task_t *p) * We want to under-estimate the load of migration sources, to * balance conservatively. */ -static inline unsigned long source_load(int cpu, int type) +static inline unsigned long __source_load(int cpu, int type, enum idle_type idle) { runqueue_t *rq = cpu_rq(cpu); - unsigned long load_now = rq->nr_running * SCHED_LOAD_SCALE; + unsigned long running = rq->nr_running; + unsigned long source_load, cpu_load = rq->cpu_load[type-1], + load_now = running * SCHED_LOAD_SCALE; + if (type == 0) - return load_now; + source_load = load_now; + else + source_load = min(cpu_load, load_now); - return min(rq->cpu_load[type-1], load_now); + if (running > 1 || (idle == NOT_IDLE && running)) + /* + * If we are busy rebalancing the load is biased by + * priority to create 'nice' support across cpus. When + * idle rebalancing we should only bias the source_load if + * there is more than one task running on that queue to + * prevent idle rebalance from trying to pull tasks from a + * queue with only one running task. + */ + source_load = source_load * rq->prio_bias / running; + + return source_load; +} + +static inline unsigned long source_load(int cpu, int type) +{ + return __source_load(cpu, type, NOT_IDLE); } /* * Return a high guess at the load of a migration-target cpu */ -static inline unsigned long target_load(int cpu, int type) +static inline unsigned long __target_load(int cpu, int type, enum idle_type idle) { runqueue_t *rq = cpu_rq(cpu); - unsigned long load_now = rq->nr_running * SCHED_LOAD_SCALE; + unsigned long running = rq->nr_running; + unsigned long target_load, cpu_load = rq->cpu_load[type-1], + load_now = running * SCHED_LOAD_SCALE; + if (type == 0) - return load_now; + target_load = load_now; + else + target_load = max(cpu_load, load_now); + + if (running > 1 || (idle == NOT_IDLE && running)) + target_load = target_load * rq->prio_bias / running; - return max(rq->cpu_load[type-1], load_now); + return target_load; +} + +static inline unsigned long target_load(int cpu, int type) +{ + return __target_load(cpu, type, NOT_IDLE); } /* @@ -1411,7 +1508,7 @@ void fastcall wake_up_new_task(task_t *p, unsigned long clone_flags) list_add_tail(&p->run_list, ¤t->run_list); p->array = current->array; p->array->nr_active++; - rq->nr_running++; + inc_nr_running(p, rq); } set_need_resched(); } else @@ -1756,9 +1853,9 @@ void pull_task(runqueue_t *src_rq, prio_array_t *src_array, task_t *p, runqueue_t *this_rq, prio_array_t *this_array, int this_cpu) { dequeue_task(p, src_array); - src_rq->nr_running--; + dec_nr_running(p, src_rq); set_task_cpu(p, this_cpu); - this_rq->nr_running++; + inc_nr_running(p, this_rq); enqueue_task(p, this_array); p->timestamp = (p->timestamp - src_rq->timestamp_last_tick) + this_rq->timestamp_last_tick; @@ -1937,9 +2034,9 @@ find_busiest_group(struct sched_domain *sd, int this_cpu, /* Bias balancing toward cpus of our domain */ if (local_group) - load = target_load(i, load_idx); + load = __target_load(i, load_idx, idle); else - load = source_load(i, load_idx); + load = __source_load(i, load_idx, idle); avg_load += load; } @@ -2044,14 +2141,15 @@ out_balanced: /* * find_busiest_queue - find the busiest runqueue among the cpus in group. */ -static runqueue_t *find_busiest_queue(struct sched_group *group) +static runqueue_t *find_busiest_queue(struct sched_group *group, + enum idle_type idle) { unsigned long load, max_load = 0; runqueue_t *busiest = NULL; int i; for_each_cpu_mask(i, group->cpumask) { - load = source_load(i, 0); + load = __source_load(i, 0, idle); if (load > max_load) { max_load = load; @@ -2095,7 +2193,7 @@ static int load_balance(int this_cpu, runqueue_t *this_rq, goto out_balanced; } - busiest = find_busiest_queue(group); + busiest = find_busiest_queue(group, idle); if (!busiest) { schedstat_inc(sd, lb_nobusyq[idle]); goto out_balanced; @@ -2218,7 +2316,7 @@ static int load_balance_newidle(int this_cpu, runqueue_t *this_rq, goto out_balanced; } - busiest = find_busiest_queue(group); + busiest = find_busiest_queue(group, NEWLY_IDLE); if (!busiest) { schedstat_inc(sd, lb_nobusyq[NEWLY_IDLE]); goto out_balanced; @@ -3451,8 +3549,10 @@ void set_user_nice(task_t *p, long nice) goto out_unlock; } array = p->array; - if (array) + if (array) { dequeue_task(p, array); + dec_prio_bias(rq, p->static_prio); + } old_prio = p->prio; new_prio = NICE_TO_PRIO(nice); @@ -3462,6 +3562,7 @@ void set_user_nice(task_t *p, long nice) if (array) { enqueue_task(p, array); + inc_prio_bias(rq, p->static_prio); /* * If the task increased its priority or is running and * lowered its priority, then reschedule its CPU: |