X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=kernel%2Fsched.c;h=4c64f85698aee2205c442f3fec09d18a3db5d4a3;hb=96f9c2e277768099479fbed7c3b69c294b1fadef;hp=a9ecac398bb9b979a4457ea0ade69259c9e7dc53;hpb=78cd9e04e0acea4f622e84ca0c760c7eae0c6854;p=linux-2.6 diff --git a/kernel/sched.c b/kernel/sched.c index a9ecac398b..4c64f85698 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -664,12 +664,58 @@ static int effective_prio(task_t *p) return prio; } +/* + * We place interactive tasks back into the active array, if possible. + * + * To guarantee that this does not starve expired tasks we ignore the + * interactivity of a task if the first expired task had to wait more + * than a 'reasonable' amount of time. This deadline timeout is + * load-dependent, as the frequency of array switched decreases with + * increasing number of running tasks. We also ignore the interactivity + * if a better static_prio task has expired, and switch periodically + * regardless, to ensure that highly interactive tasks do not starve + * the less fortunate for unreasonably long periods. + */ +static inline int expired_starving(runqueue_t *rq) +{ + int limit; + + /* + * Arrays were recently switched, all is well + */ + if (!rq->expired_timestamp) + return 0; + + limit = STARVATION_LIMIT * rq->nr_running; + + /* + * It's time to switch arrays + */ + if (jiffies - rq->expired_timestamp >= limit) + return 1; + + /* + * There's a better selection in the expired array + */ + if (rq->curr->static_prio > rq->best_expired_prio) + return 1; + + /* + * All is well + */ + return 0; +} + /* * __activate_task - move a task to the runqueue. */ -static inline void __activate_task(task_t *p, runqueue_t *rq) +static void __activate_task(task_t *p, runqueue_t *rq) { - enqueue_task(p, rq->active); + prio_array_t *target = rq->active; + + if (unlikely(batch_task(p) || (expired_starving(rq) && !rt_task(p)))) + target = rq->expired; + enqueue_task(p, target); rq->nr_running++; } @@ -688,7 +734,7 @@ static int recalc_task_prio(task_t *p, unsigned long long now) unsigned long long __sleep_time = now - p->timestamp; unsigned long sleep_time; - if (unlikely(p->policy == SCHED_BATCH)) + if (batch_task(p)) sleep_time = 0; else { if (__sleep_time > NS_MAX_SLEEP_AVG) @@ -700,21 +746,25 @@ static int recalc_task_prio(task_t *p, unsigned long long now) if (likely(sleep_time > 0)) { /* * User tasks that sleep a long time are categorised as - * idle and will get just interactive status to stay active & - * prevent them suddenly becoming cpu hogs and starving - * other processes. + * idle. They will only have their sleep_avg increased to a + * level that makes them just interactive priority to stay + * active yet prevent them suddenly becoming cpu hogs and + * starving other processes. */ - if (p->mm && p->activated != -1 && - sleep_time > INTERACTIVE_SLEEP(p)) { - p->sleep_avg = JIFFIES_TO_NS(MAX_SLEEP_AVG - - DEF_TIMESLICE); + if (p->mm && sleep_time > INTERACTIVE_SLEEP(p)) { + unsigned long ceiling; + + ceiling = JIFFIES_TO_NS(MAX_SLEEP_AVG - + DEF_TIMESLICE); + if (p->sleep_avg < ceiling) + p->sleep_avg = ceiling; } else { /* * Tasks waking from uninterruptible sleep are * limited in their sleep_avg rise as they * are likely to be waiting on I/O */ - if (p->activated == -1 && p->mm) { + if (p->sleep_type == SLEEP_NONINTERACTIVE && p->mm) { if (p->sleep_avg >= INTERACTIVE_SLEEP(p)) sleep_time = 0; else if (p->sleep_avg + sleep_time >= @@ -769,7 +819,7 @@ static void activate_task(task_t *p, runqueue_t *rq, int local) * This checks to make sure it's not an uninterruptible task * that is now waking up. */ - if (!p->activated) { + if (p->sleep_type == SLEEP_NORMAL) { /* * Tasks which were woken up by interrupts (ie. hw events) * are most likely of interactive nature. So we give them @@ -778,13 +828,13 @@ static void activate_task(task_t *p, runqueue_t *rq, int local) * on a CPU, first time around: */ if (in_interrupt()) - p->activated = 2; + p->sleep_type = SLEEP_INTERRUPTED; else { /* * Normal first-time wakeups get a credit too for * on-runqueue time, but it will be weighted down: */ - p->activated = 1; + p->sleep_type = SLEEP_INTERACTIVE; } } p->timestamp = now; @@ -1272,19 +1322,19 @@ out_activate: * Tasks on involuntary sleep don't earn * sleep_avg beyond just interactive state. */ - p->activated = -1; - } + p->sleep_type = SLEEP_NONINTERACTIVE; + } else /* * Tasks that have marked their sleep as noninteractive get - * woken up without updating their sleep average. (i.e. their - * sleep is handled in a priority-neutral manner, no priority - * boost and no penalty.) + * woken up with their sleep average not weighted in an + * interactive way. */ - if (old_state & TASK_NONINTERACTIVE) - __activate_task(p, rq); - else - activate_task(p, rq, cpu == this_cpu); + if (old_state & TASK_NONINTERACTIVE) + p->sleep_type = SLEEP_NONINTERACTIVE; + + + activate_task(p, rq, cpu == this_cpu); /* * Sync wakeups (i.e. those types of wakeups where the waker * has indicated that it will leave the CPU in short order) @@ -1658,6 +1708,21 @@ unsigned long nr_iowait(void) return sum; } +unsigned long nr_active(void) +{ + unsigned long i, running = 0, uninterruptible = 0; + + for_each_online_cpu(i) { + running += cpu_rq(i)->nr_running; + uninterruptible += cpu_rq(i)->nr_uninterruptible; + } + + if (unlikely((long)uninterruptible < 0)) + uninterruptible = 0; + + return running + uninterruptible; +} + #ifdef CONFIG_SMP /* @@ -2466,22 +2531,6 @@ unsigned long long current_sched_time(const task_t *tsk) return ns; } -/* - * We place interactive tasks back into the active array, if possible. - * - * To guarantee that this does not starve expired tasks we ignore the - * interactivity of a task if the first expired task had to wait more - * than a 'reasonable' amount of time. This deadline timeout is - * load-dependent, as the frequency of array switched decreases with - * increasing number of running tasks. We also ignore the interactivity - * if a better static_prio task has expired: - */ -#define EXPIRED_STARVING(rq) \ - ((STARVATION_LIMIT && ((rq)->expired_timestamp && \ - (jiffies - (rq)->expired_timestamp >= \ - STARVATION_LIMIT * ((rq)->nr_running) + 1))) || \ - ((rq)->curr->static_prio > (rq)->best_expired_prio)) - /* * Account user cpu time to a process. * @p: the process that the cpu time gets accounted to @@ -2617,7 +2666,7 @@ void scheduler_tick(void) if (!rq->expired_timestamp) rq->expired_timestamp = jiffies; - if (!TASK_INTERACTIVE(p) || EXPIRED_STARVING(rq)) { + if (!TASK_INTERACTIVE(p) || expired_starving(rq)) { enqueue_task(p, rq->expired); if (p->static_prio < rq->best_expired_prio) rq->best_expired_prio = p->static_prio; @@ -2860,6 +2909,12 @@ EXPORT_SYMBOL(sub_preempt_count); #endif +static inline int interactive_sleep(enum sleep_type sleep_type) +{ + return (sleep_type == SLEEP_INTERACTIVE || + sleep_type == SLEEP_INTERRUPTED); +} + /* * schedule() is the main scheduler function. */ @@ -2983,12 +3038,12 @@ go_idle: queue = array->queue + idx; next = list_entry(queue->next, task_t, run_list); - if (!rt_task(next) && next->activated > 0) { + if (!rt_task(next) && interactive_sleep(next->sleep_type)) { unsigned long long delta = now - next->timestamp; if (unlikely((long long)(now - next->timestamp) < 0)) delta = 0; - if (next->activated == 1) + if (next->sleep_type == SLEEP_INTERACTIVE) delta = delta * (ON_RUNQUEUE_WEIGHT * 128 / 100) / 128; array = next->array; @@ -2998,10 +3053,9 @@ go_idle: dequeue_task(next, array); next->prio = new_prio; enqueue_task(next, array); - } else - requeue_task(next, array); + } } - next->activated = 0; + next->sleep_type = SLEEP_NORMAL; switch_tasks: if (next == rq->idle) schedstat_inc(rq, sched_goidle); @@ -4760,7 +4814,7 @@ static int migration_call(struct notifier_block *nfb, unsigned long action, /* Register at highest priority so that task migration (migrate_all_tasks) * happens before everything else. */ -static struct notifier_block __devinitdata migration_notifier = { +static struct notifier_block migration_notifier = { .notifier_call = migration_call, .priority = 10 };