diff options
| -rw-r--r-- | include/linux/init_task.h | 2 | ||||
| -rw-r--r-- | include/linux/sched.h | 21 | ||||
| -rw-r--r-- | kernel/sched.c | 189 |
3 files changed, 181 insertions, 31 deletions
diff --git a/include/linux/init_task.h b/include/linux/init_task.h index e127ef7..678c1a9 100644 --- a/include/linux/init_task.h +++ b/include/linux/init_task.h @@ -87,6 +87,7 @@ extern struct group_info init_groups; .lock_depth = -1, \ .prio = MAX_PRIO-20, \ .static_prio = MAX_PRIO-20, \ + .normal_prio = MAX_PRIO-20, \ .policy = SCHED_NORMAL, \ .cpus_allowed = CPU_MASK_ALL, \ .mm = NULL, \ @@ -122,6 +123,7 @@ extern struct group_info init_groups; .journal_info = NULL, \ .cpu_timers = INIT_CPU_TIMERS(tsk.cpu_timers), \ .fs_excl = ATOMIC_INIT(0), \ + .pi_lock = SPIN_LOCK_UNLOCKED, \ } diff --git a/include/linux/sched.h b/include/linux/sched.h index 0bc81a1..6f16764 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -495,8 +495,11 @@ struct signal_struct { #define MAX_PRIO (MAX_RT_PRIO + 40) -#define rt_task(p) (unlikely((p)->prio < MAX_RT_PRIO)) +#define rt_prio(prio) unlikely((prio) < MAX_RT_PRIO) +#define rt_task(p) rt_prio((p)->prio) #define batch_task(p) (unlikely((p)->policy == SCHED_BATCH)) +#define has_rt_policy(p) \ + unlikely((p)->policy != SCHED_NORMAL && (p)->policy != SCHED_BATCH) /* * Some day this will be a full-fledged user tracking system.. @@ -725,7 +728,7 @@ struct task_struct { #endif #endif int load_weight; /* for niceness load balancing purposes */ - int prio, static_prio; + int prio, static_prio, normal_prio; struct list_head run_list; prio_array_t *array; @@ -852,6 +855,9 @@ struct task_struct { /* Protection of (de-)allocation: mm, files, fs, tty, keyrings */ spinlock_t alloc_lock; + /* Protection of the PI data structures: */ + spinlock_t pi_lock; + #ifdef CONFIG_DEBUG_MUTEXES /* mutex deadlock detection */ struct mutex_waiter *blocked_on; @@ -1018,6 +1024,17 @@ static inline void idle_task_exit(void) {} #endif extern void sched_idle_next(void); + +#ifdef CONFIG_RT_MUTEXES +extern int rt_mutex_getprio(task_t *p); +extern void rt_mutex_setprio(task_t *p, int prio); +#else +static inline int rt_mutex_getprio(task_t *p) +{ + return p->normal_prio; +} +#endif + extern void set_user_nice(task_t *p, long nice); extern int task_prio(const task_t *p); extern int task_nice(const task_t *p); diff --git a/kernel/sched.c b/kernel/sched.c index 15abf08..08431f0 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -355,6 +355,25 @@ static inline void finish_lock_switch(runqueue_t *rq, task_t *prev) #endif /* __ARCH_WANT_UNLOCKED_CTXSW */ /* + * __task_rq_lock - lock the runqueue a given task resides on. + * Must be called interrupts disabled. + */ +static inline runqueue_t *__task_rq_lock(task_t *p) + __acquires(rq->lock) +{ + struct runqueue *rq; + +repeat_lock_task: + rq = task_rq(p); + spin_lock(&rq->lock); + if (unlikely(rq != task_rq(p))) { + spin_unlock(&rq->lock); + goto repeat_lock_task; + } + return rq; +} + +/* * task_rq_lock - lock the runqueue a given task resides on and disable * interrupts. Note the ordering: we can safely lookup the task_rq without * explicitly disabling preemption. @@ -375,6 +394,12 @@ repeat_lock_task: return rq; } +static inline void __task_rq_unlock(runqueue_t *rq) + __releases(rq->lock) +{ + spin_unlock(&rq->lock); +} + static inline void task_rq_unlock(runqueue_t *rq, unsigned long *flags) __releases(rq->lock) { @@ -638,7 +663,7 @@ static inline void enqueue_task_head(struct task_struct *p, prio_array_t *array) } /* - * effective_prio - return the priority that is based on the static + * __normal_prio - return the priority that is based on the static * priority but is modified by bonuses/penalties. * * We scale the actual sleep average [0 .... MAX_SLEEP_AVG] @@ -651,13 +676,11 @@ static inline void enqueue_task_head(struct task_struct *p, prio_array_t *array) * * Both properties are important to certain workloads. */ -static int effective_prio(task_t *p) + +static inline int __normal_prio(task_t *p) { int bonus, prio; - if (rt_task(p)) - return p->prio; - bonus = CURRENT_BONUS(p) - MAX_BONUS / 2; prio = p->static_prio - bonus; @@ -692,7 +715,7 @@ static int effective_prio(task_t *p) static void set_load_weight(task_t *p) { - if (rt_task(p)) { + if (has_rt_policy(p)) { #ifdef CONFIG_SMP if (p == task_rq(p)->migration_thread) /* @@ -731,6 +754,44 @@ static inline void dec_nr_running(task_t *p, runqueue_t *rq) } /* + * Calculate the expected normal priority: i.e. priority + * without taking RT-inheritance into account. Might be + * boosted by interactivity modifiers. Changes upon fork, + * setprio syscalls, and whenever the interactivity + * estimator recalculates. + */ +static inline int normal_prio(task_t *p) +{ + int prio; + + if (has_rt_policy(p)) + prio = MAX_RT_PRIO-1 - p->rt_priority; + else + prio = __normal_prio(p); + return prio; +} + +/* + * Calculate the current priority, i.e. the priority + * taken into account by the scheduler. This value might + * be boosted by RT tasks, or might be boosted by + * interactivity modifiers. Will be RT if the task got + * RT-boosted. If not then it returns p->normal_prio. + */ +static int effective_prio(task_t *p) +{ + p->normal_prio = normal_prio(p); + /* + * If we are RT tasks or we were boosted to RT priority, + * keep the priority unchanged. Otherwise, update priority + * to the normal priority: + */ + if (!rt_prio(p->prio)) + return p->normal_prio; + return p->prio; +} + +/* * __activate_task - move a task to the runqueue. */ static void __activate_task(task_t *p, runqueue_t *rq) @@ -752,6 +813,10 @@ static inline void __activate_idle_task(task_t *p, runqueue_t *rq) inc_nr_running(p, rq); } +/* + * Recalculate p->normal_prio and p->prio after having slept, + * updating the sleep-average too: + */ static int recalc_task_prio(task_t *p, unsigned long long now) { /* Caller must always ensure 'now >= p->timestamp' */ @@ -1448,6 +1513,12 @@ void fastcall sched_fork(task_t *p, int clone_flags) * event cannot wake it up and insert it on the runqueue either. */ p->state = TASK_RUNNING; + + /* + * Make sure we do not leak PI boosting priority to the child: + */ + p->prio = current->normal_prio; + INIT_LIST_HEAD(&p->run_list); p->array = NULL; #ifdef CONFIG_SCHEDSTATS @@ -1527,6 +1598,7 @@ void fastcall wake_up_new_task(task_t *p, unsigned long clone_flags) __activate_task(p, rq); else { p->prio = current->prio; + p->normal_prio = current->normal_prio; list_add_tail(&p->run_list, ¤t->run_list); p->array = current->array; p->array->nr_active++; @@ -3668,12 +3740,65 @@ long fastcall __sched sleep_on_timeout(wait_queue_head_t *q, long timeout) EXPORT_SYMBOL(sleep_on_timeout); +#ifdef CONFIG_RT_MUTEXES + +/* + * rt_mutex_setprio - set the current priority of a task + * @p: task + * @prio: prio value (kernel-internal form) + * + * This function changes the 'effective' priority of a task. It does + * not touch ->normal_prio like __setscheduler(). + * + * Used by the rt_mutex code to implement priority inheritance logic. + */ +void rt_mutex_setprio(task_t *p, int prio) +{ + unsigned long flags; + prio_array_t *array; + runqueue_t *rq; + int oldprio; + + BUG_ON(prio < 0 || prio > MAX_PRIO); + + rq = task_rq_lock(p, &flags); + + oldprio = p->prio; + array = p->array; + if (array) + dequeue_task(p, array); + p->prio = prio; + + if (array) { + /* + * If changing to an RT priority then queue it + * in the active array! + */ + if (rt_task(p)) + array = rq->active; + enqueue_task(p, array); + /* + * Reschedule if we are currently running on this runqueue and + * our priority decreased, or if we are not currently running on + * this runqueue and our priority is higher than the current's + */ + if (task_running(rq, p)) { + if (p->prio > oldprio) + resched_task(rq->curr); + } else if (TASK_PREEMPTS_CURR(p, rq)) + resched_task(rq->curr); + } + task_rq_unlock(rq, &flags); +} + +#endif + void set_user_nice(task_t *p, long nice) { unsigned long flags; prio_array_t *array; runqueue_t *rq; - int old_prio, new_prio, delta; + int old_prio, delta; if (TASK_NICE(p) == nice || nice < -20 || nice > 19) return; @@ -3688,7 +3813,7 @@ void set_user_nice(task_t *p, long nice) * it wont have any effect on scheduling until the task is * not SCHED_NORMAL/SCHED_BATCH: */ - if (rt_task(p)) { + if (has_rt_policy(p)) { p->static_prio = NICE_TO_PRIO(nice); goto out_unlock; } @@ -3698,12 +3823,11 @@ void set_user_nice(task_t *p, long nice) dec_raw_weighted_load(rq, p); } - old_prio = p->prio; - new_prio = NICE_TO_PRIO(nice); - delta = new_prio - old_prio; p->static_prio = NICE_TO_PRIO(nice); set_load_weight(p); - p->prio += delta; + old_prio = p->prio; + p->prio = effective_prio(p); + delta = p->prio - old_prio; if (array) { enqueue_task(p, array); @@ -3718,7 +3842,6 @@ void set_user_nice(task_t *p, long nice) out_unlock: task_rq_unlock(rq, &flags); } - EXPORT_SYMBOL(set_user_nice); /* @@ -3833,16 +3956,14 @@ static void __setscheduler(struct task_struct *p, int policy, int prio) BUG_ON(p->array); p->policy = policy; p->rt_priority = prio; - if (policy != SCHED_NORMAL && policy != SCHED_BATCH) { - p->prio = MAX_RT_PRIO-1 - p->rt_priority; - } else { - p->prio = p->static_prio; - /* - * SCHED_BATCH tasks are treated as perpetual CPU hogs: - */ - if (policy == SCHED_BATCH) - p->sleep_avg = 0; - } + p->normal_prio = normal_prio(p); + /* we are holding p->pi_lock already */ + p->prio = rt_mutex_getprio(p); + /* + * SCHED_BATCH tasks are treated as perpetual CPU hogs: + */ + if (policy == SCHED_BATCH) + p->sleep_avg = 0; set_load_weight(p); } @@ -3912,14 +4033,20 @@ recheck: if (retval) return retval; /* + * make sure no PI-waiters arrive (or leave) while we are + * changing the priority of the task: + */ + spin_lock_irqsave(&p->pi_lock, flags); + /* * To be able to change p->policy safely, the apropriate * runqueue lock must be held. */ - rq = task_rq_lock(p, &flags); + rq = __task_rq_lock(p); /* recheck policy now with rq lock held */ if (unlikely(oldpolicy != -1 && oldpolicy != p->policy)) { policy = oldpolicy = -1; - task_rq_unlock(rq, &flags); + __task_rq_unlock(rq); + spin_unlock_irqrestore(&p->pi_lock, flags); goto recheck; } array = p->array; @@ -3940,7 +4067,9 @@ recheck: } else if (TASK_PREEMPTS_CURR(p, rq)) resched_task(rq->curr); } - task_rq_unlock(rq, &flags); + __task_rq_unlock(rq); + spin_unlock_irqrestore(&p->pi_lock, flags); + return 0; } EXPORT_SYMBOL_GPL(sched_setscheduler); @@ -4575,7 +4704,7 @@ void __devinit init_idle(task_t *idle, int cpu) idle->timestamp = sched_clock(); idle->sleep_avg = 0; idle->array = NULL; - idle->prio = MAX_PRIO; + idle->prio = idle->normal_prio = MAX_PRIO; idle->state = TASK_RUNNING; idle->cpus_allowed = cpumask_of_cpu(cpu); set_task_cpu(idle, cpu); @@ -6582,7 +6711,8 @@ void normalize_rt_tasks(void) if (!rt_task(p)) continue; - rq = task_rq_lock(p, &flags); + spin_lock_irqsave(&p->pi_lock, flags); + rq = __task_rq_lock(p); array = p->array; if (array) @@ -6593,7 +6723,8 @@ void normalize_rt_tasks(void) resched_task(rq->curr); } - task_rq_unlock(rq, &flags); + __task_rq_unlock(rq); + spin_unlock_irqrestore(&p->pi_lock, flags); } read_unlock_irq(&tasklist_lock); } |