2 * Copyright (C) 2007-2010 Lawrence Livermore National Security, LLC.
3 * Copyright (C) 2007 The Regents of the University of California.
4 * Produced at Lawrence Livermore National Laboratory (cf, DISCLAIMER).
5 * Written by Brian Behlendorf <behlendorf1@llnl.gov>.
8 * This file is part of the SPL, Solaris Porting Layer.
9 * For details, see <http://zfsonlinux.org/>.
11 * The SPL is free software; you can redistribute it and/or modify it
12 * under the terms of the GNU General Public License as published by the
13 * Free Software Foundation; either version 2 of the License, or (at your
14 * option) any later version.
16 * The SPL is distributed in the hope that it will be useful, but WITHOUT
17 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
18 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
21 * You should have received a copy of the GNU General Public License along
22 * with the SPL. If not, see <http://www.gnu.org/licenses/>.
24 * Solaris Porting Layer (SPL) Task Queue Implementation.
27 #include <sys/taskq.h>
31 int spl_taskq_thread_bind = 0;
32 module_param(spl_taskq_thread_bind, int, 0644);
33 MODULE_PARM_DESC(spl_taskq_thread_bind, "Bind taskq thread to CPU by default");
36 int spl_taskq_thread_dynamic = 1;
37 module_param(spl_taskq_thread_dynamic, int, 0644);
38 MODULE_PARM_DESC(spl_taskq_thread_dynamic, "Allow dynamic taskq threads");
40 int spl_taskq_thread_priority = 1;
41 module_param(spl_taskq_thread_priority, int, 0644);
42 MODULE_PARM_DESC(spl_taskq_thread_priority,
43 "Allow non-default priority for taskq threads");
45 int spl_taskq_thread_sequential = 4;
46 module_param(spl_taskq_thread_sequential, int, 0644);
47 MODULE_PARM_DESC(spl_taskq_thread_sequential,
48 "Create new taskq threads after N sequential tasks");
50 /* Global system-wide dynamic task queue available for all consumers */
51 taskq_t *system_taskq;
52 EXPORT_SYMBOL(system_taskq);
54 /* Private dedicated taskq for creating new taskq threads on demand. */
55 static taskq_t *dynamic_taskq;
56 static taskq_thread_t *taskq_thread_create(taskq_t *);
58 /* List of all taskqs */
60 DECLARE_RWSEM(tq_list_sem);
61 static uint_t taskq_tsd;
64 task_km_flags(uint_t flags)
66 if (flags & TQ_NOSLEEP)
69 if (flags & TQ_PUSHPAGE)
76 * taskq_find_by_name - Find the largest instance number of a named taskq.
79 taskq_find_by_name(const char *name)
81 struct list_head *tql;
84 list_for_each_prev(tql, &tq_list) {
85 tq = list_entry(tql, taskq_t, tq_taskqs);
86 if (strcmp(name, tq->tq_name) == 0)
87 return tq->tq_instance;
93 * NOTE: Must be called with tq->tq_lock held, returns a list_t which
94 * is not attached to the free, work, or pending taskq lists.
97 task_alloc(taskq_t *tq, uint_t flags, unsigned long *irqflags)
103 ASSERT(spin_is_locked(&tq->tq_lock));
105 /* Acquire taskq_ent_t's from free list if available */
106 if (!list_empty(&tq->tq_free_list) && !(flags & TQ_NEW)) {
107 t = list_entry(tq->tq_free_list.next, taskq_ent_t, tqent_list);
109 ASSERT(!(t->tqent_flags & TQENT_FLAG_PREALLOC));
110 ASSERT(!(t->tqent_flags & TQENT_FLAG_CANCEL));
111 ASSERT(!timer_pending(&t->tqent_timer));
113 list_del_init(&t->tqent_list);
117 /* Free list is empty and memory allocations are prohibited */
118 if (flags & TQ_NOALLOC)
121 /* Hit maximum taskq_ent_t pool size */
122 if (tq->tq_nalloc >= tq->tq_maxalloc) {
123 if (flags & TQ_NOSLEEP)
127 * Sleep periodically polling the free list for an available
128 * taskq_ent_t. Dispatching with TQ_SLEEP should always succeed
129 * but we cannot block forever waiting for an taskq_ent_t to
130 * show up in the free list, otherwise a deadlock can happen.
132 * Therefore, we need to allocate a new task even if the number
133 * of allocated tasks is above tq->tq_maxalloc, but we still
134 * end up delaying the task allocation by one second, thereby
135 * throttling the task dispatch rate.
137 spin_unlock_irqrestore(&tq->tq_lock, *irqflags);
138 schedule_timeout(HZ / 100);
139 spin_lock_irqsave_nested(&tq->tq_lock, *irqflags,
147 spin_unlock_irqrestore(&tq->tq_lock, *irqflags);
148 t = kmem_alloc(sizeof (taskq_ent_t), task_km_flags(flags));
149 spin_lock_irqsave_nested(&tq->tq_lock, *irqflags, tq->tq_lock_class);
160 * NOTE: Must be called with tq->tq_lock held, expects the taskq_ent_t
161 * to already be removed from the free, work, or pending taskq lists.
164 task_free(taskq_t *tq, taskq_ent_t *t)
168 ASSERT(spin_is_locked(&tq->tq_lock));
169 ASSERT(list_empty(&t->tqent_list));
170 ASSERT(!timer_pending(&t->tqent_timer));
172 kmem_free(t, sizeof (taskq_ent_t));
177 * NOTE: Must be called with tq->tq_lock held, either destroys the
178 * taskq_ent_t if too many exist or moves it to the free list for later use.
181 task_done(taskq_t *tq, taskq_ent_t *t)
185 ASSERT(spin_is_locked(&tq->tq_lock));
187 /* Wake tasks blocked in taskq_wait_id() */
188 wake_up_all(&t->tqent_waitq);
190 list_del_init(&t->tqent_list);
192 if (tq->tq_nalloc <= tq->tq_minalloc) {
193 t->tqent_id = TASKQID_INVALID;
194 t->tqent_func = NULL;
198 list_add_tail(&t->tqent_list, &tq->tq_free_list);
205 * When a delayed task timer expires remove it from the delay list and
206 * add it to the priority list in order for immediate processing.
209 task_expire(unsigned long data)
211 taskq_ent_t *w, *t = (taskq_ent_t *)data;
212 taskq_t *tq = t->tqent_taskq;
216 spin_lock_irqsave_nested(&tq->tq_lock, flags, tq->tq_lock_class);
218 if (t->tqent_flags & TQENT_FLAG_CANCEL) {
219 ASSERT(list_empty(&t->tqent_list));
220 spin_unlock_irqrestore(&tq->tq_lock, flags);
224 t->tqent_birth = jiffies;
226 * The priority list must be maintained in strict task id order
227 * from lowest to highest for lowest_id to be easily calculable.
229 list_del(&t->tqent_list);
230 list_for_each_prev(l, &tq->tq_prio_list) {
231 w = list_entry(l, taskq_ent_t, tqent_list);
232 if (w->tqent_id < t->tqent_id) {
233 list_add(&t->tqent_list, l);
237 if (l == &tq->tq_prio_list)
238 list_add(&t->tqent_list, &tq->tq_prio_list);
240 spin_unlock_irqrestore(&tq->tq_lock, flags);
242 wake_up(&tq->tq_work_waitq);
246 * Returns the lowest incomplete taskqid_t. The taskqid_t may
247 * be queued on the pending list, on the priority list, on the
248 * delay list, or on the work list currently being handled, but
249 * it is not 100% complete yet.
252 taskq_lowest_id(taskq_t *tq)
254 taskqid_t lowest_id = tq->tq_next_id;
259 ASSERT(spin_is_locked(&tq->tq_lock));
261 if (!list_empty(&tq->tq_pend_list)) {
262 t = list_entry(tq->tq_pend_list.next, taskq_ent_t, tqent_list);
263 lowest_id = MIN(lowest_id, t->tqent_id);
266 if (!list_empty(&tq->tq_prio_list)) {
267 t = list_entry(tq->tq_prio_list.next, taskq_ent_t, tqent_list);
268 lowest_id = MIN(lowest_id, t->tqent_id);
271 if (!list_empty(&tq->tq_delay_list)) {
272 t = list_entry(tq->tq_delay_list.next, taskq_ent_t, tqent_list);
273 lowest_id = MIN(lowest_id, t->tqent_id);
276 if (!list_empty(&tq->tq_active_list)) {
277 tqt = list_entry(tq->tq_active_list.next, taskq_thread_t,
279 ASSERT(tqt->tqt_id != TASKQID_INVALID);
280 lowest_id = MIN(lowest_id, tqt->tqt_id);
287 * Insert a task into a list keeping the list sorted by increasing taskqid.
290 taskq_insert_in_order(taskq_t *tq, taskq_thread_t *tqt)
297 ASSERT(spin_is_locked(&tq->tq_lock));
299 list_for_each_prev(l, &tq->tq_active_list) {
300 w = list_entry(l, taskq_thread_t, tqt_active_list);
301 if (w->tqt_id < tqt->tqt_id) {
302 list_add(&tqt->tqt_active_list, l);
306 if (l == &tq->tq_active_list)
307 list_add(&tqt->tqt_active_list, &tq->tq_active_list);
311 * Find and return a task from the given list if it exists. The list
312 * must be in lowest to highest task id order.
315 taskq_find_list(taskq_t *tq, struct list_head *lh, taskqid_t id)
320 ASSERT(spin_is_locked(&tq->tq_lock));
322 list_for_each(l, lh) {
323 t = list_entry(l, taskq_ent_t, tqent_list);
325 if (t->tqent_id == id)
328 if (t->tqent_id > id)
336 * Find an already dispatched task given the task id regardless of what
337 * state it is in. If a task is still pending or executing it will be
338 * returned and 'active' set appropriately. If the task has already
339 * been run then NULL is returned.
342 taskq_find(taskq_t *tq, taskqid_t id, int *active)
348 ASSERT(spin_is_locked(&tq->tq_lock));
351 t = taskq_find_list(tq, &tq->tq_delay_list, id);
355 t = taskq_find_list(tq, &tq->tq_prio_list, id);
359 t = taskq_find_list(tq, &tq->tq_pend_list, id);
363 list_for_each(l, &tq->tq_active_list) {
364 tqt = list_entry(l, taskq_thread_t, tqt_active_list);
365 if (tqt->tqt_id == id) {
376 * Theory for the taskq_wait_id(), taskq_wait_outstanding(), and
377 * taskq_wait() functions below.
379 * Taskq waiting is accomplished by tracking the lowest outstanding task
380 * id and the next available task id. As tasks are dispatched they are
381 * added to the tail of the pending, priority, or delay lists. As worker
382 * threads become available the tasks are removed from the heads of these
383 * lists and linked to the worker threads. This ensures the lists are
384 * kept sorted by lowest to highest task id.
386 * Therefore the lowest outstanding task id can be quickly determined by
387 * checking the head item from all of these lists. This value is stored
388 * with the taskq as the lowest id. It only needs to be recalculated when
389 * either the task with the current lowest id completes or is canceled.
391 * By blocking until the lowest task id exceeds the passed task id the
392 * taskq_wait_outstanding() function can be easily implemented. Similarly,
393 * by blocking until the lowest task id matches the next task id taskq_wait()
394 * can be implemented.
396 * Callers should be aware that when there are multiple worked threads it
397 * is possible for larger task ids to complete before smaller ones. Also
398 * when the taskq contains delay tasks with small task ids callers may
399 * block for a considerable length of time waiting for them to expire and
403 taskq_wait_id_check(taskq_t *tq, taskqid_t id)
409 spin_lock_irqsave_nested(&tq->tq_lock, flags, tq->tq_lock_class);
410 rc = (taskq_find(tq, id, &active) == NULL);
411 spin_unlock_irqrestore(&tq->tq_lock, flags);
417 * The taskq_wait_id() function blocks until the passed task id completes.
418 * This does not guarantee that all lower task ids have completed.
421 taskq_wait_id(taskq_t *tq, taskqid_t id)
423 wait_event(tq->tq_wait_waitq, taskq_wait_id_check(tq, id));
425 EXPORT_SYMBOL(taskq_wait_id);
428 taskq_wait_outstanding_check(taskq_t *tq, taskqid_t id)
433 spin_lock_irqsave_nested(&tq->tq_lock, flags, tq->tq_lock_class);
434 rc = (id < tq->tq_lowest_id);
435 spin_unlock_irqrestore(&tq->tq_lock, flags);
441 * The taskq_wait_outstanding() function will block until all tasks with a
442 * lower taskqid than the passed 'id' have been completed. Note that all
443 * task id's are assigned monotonically at dispatch time. Zero may be
444 * passed for the id to indicate all tasks dispatch up to this point,
445 * but not after, should be waited for.
448 taskq_wait_outstanding(taskq_t *tq, taskqid_t id)
450 id = id ? id : tq->tq_next_id - 1;
451 wait_event(tq->tq_wait_waitq, taskq_wait_outstanding_check(tq, id));
453 EXPORT_SYMBOL(taskq_wait_outstanding);
456 taskq_wait_check(taskq_t *tq)
461 spin_lock_irqsave_nested(&tq->tq_lock, flags, tq->tq_lock_class);
462 rc = (tq->tq_lowest_id == tq->tq_next_id);
463 spin_unlock_irqrestore(&tq->tq_lock, flags);
469 * The taskq_wait() function will block until the taskq is empty.
470 * This means that if a taskq re-dispatches work to itself taskq_wait()
471 * callers will block indefinitely.
474 taskq_wait(taskq_t *tq)
476 wait_event(tq->tq_wait_waitq, taskq_wait_check(tq));
478 EXPORT_SYMBOL(taskq_wait);
481 taskq_member(taskq_t *tq, kthread_t *t)
483 return (tq == (taskq_t *)tsd_get_by_thread(taskq_tsd, t));
485 EXPORT_SYMBOL(taskq_member);
488 * Cancel an already dispatched task given the task id. Still pending tasks
489 * will be immediately canceled, and if the task is active the function will
490 * block until it completes. Preallocated tasks which are canceled must be
491 * freed by the caller.
494 taskq_cancel_id(taskq_t *tq, taskqid_t id)
503 spin_lock_irqsave_nested(&tq->tq_lock, flags, tq->tq_lock_class);
504 t = taskq_find(tq, id, &active);
506 list_del_init(&t->tqent_list);
507 t->tqent_flags |= TQENT_FLAG_CANCEL;
510 * When canceling the lowest outstanding task id we
511 * must recalculate the new lowest outstanding id.
513 if (tq->tq_lowest_id == t->tqent_id) {
514 tq->tq_lowest_id = taskq_lowest_id(tq);
515 ASSERT3S(tq->tq_lowest_id, >, t->tqent_id);
519 * The task_expire() function takes the tq->tq_lock so drop
520 * drop the lock before synchronously cancelling the timer.
522 if (timer_pending(&t->tqent_timer)) {
523 spin_unlock_irqrestore(&tq->tq_lock, flags);
524 del_timer_sync(&t->tqent_timer);
525 spin_lock_irqsave_nested(&tq->tq_lock, flags,
529 if (!(t->tqent_flags & TQENT_FLAG_PREALLOC))
534 spin_unlock_irqrestore(&tq->tq_lock, flags);
537 taskq_wait_id(tq, id);
543 EXPORT_SYMBOL(taskq_cancel_id);
545 static int taskq_thread_spawn(taskq_t *tq);
548 taskq_dispatch(taskq_t *tq, task_func_t func, void *arg, uint_t flags)
551 taskqid_t rc = TASKQID_INVALID;
552 unsigned long irqflags;
557 spin_lock_irqsave_nested(&tq->tq_lock, irqflags, tq->tq_lock_class);
559 /* Taskq being destroyed and all tasks drained */
560 if (!(tq->tq_flags & TASKQ_ACTIVE))
563 /* Do not queue the task unless there is idle thread for it */
564 ASSERT(tq->tq_nactive <= tq->tq_nthreads);
565 if ((flags & TQ_NOQUEUE) && (tq->tq_nactive == tq->tq_nthreads)) {
566 /* Dynamic taskq may be able to spawn another thread */
567 if (!(tq->tq_flags & TASKQ_DYNAMIC) || taskq_thread_spawn(tq) == 0)
571 if ((t = task_alloc(tq, flags, &irqflags)) == NULL)
574 spin_lock(&t->tqent_lock);
576 /* Queue to the front of the list to enforce TQ_NOQUEUE semantics */
577 if (flags & TQ_NOQUEUE)
578 list_add(&t->tqent_list, &tq->tq_prio_list);
579 /* Queue to the priority list instead of the pending list */
580 else if (flags & TQ_FRONT)
581 list_add_tail(&t->tqent_list, &tq->tq_prio_list);
583 list_add_tail(&t->tqent_list, &tq->tq_pend_list);
585 t->tqent_id = rc = tq->tq_next_id;
587 t->tqent_func = func;
590 t->tqent_timer.data = 0;
591 t->tqent_timer.function = NULL;
592 t->tqent_timer.expires = 0;
593 t->tqent_birth = jiffies;
595 ASSERT(!(t->tqent_flags & TQENT_FLAG_PREALLOC));
597 spin_unlock(&t->tqent_lock);
599 wake_up(&tq->tq_work_waitq);
601 /* Spawn additional taskq threads if required. */
602 if (!(flags & TQ_NOQUEUE) && tq->tq_nactive == tq->tq_nthreads)
603 (void) taskq_thread_spawn(tq);
605 spin_unlock_irqrestore(&tq->tq_lock, irqflags);
608 EXPORT_SYMBOL(taskq_dispatch);
611 taskq_dispatch_delay(taskq_t *tq, task_func_t func, void *arg,
612 uint_t flags, clock_t expire_time)
614 taskqid_t rc = TASKQID_INVALID;
616 unsigned long irqflags;
621 spin_lock_irqsave_nested(&tq->tq_lock, irqflags, tq->tq_lock_class);
623 /* Taskq being destroyed and all tasks drained */
624 if (!(tq->tq_flags & TASKQ_ACTIVE))
627 if ((t = task_alloc(tq, flags, &irqflags)) == NULL)
630 spin_lock(&t->tqent_lock);
632 /* Queue to the delay list for subsequent execution */
633 list_add_tail(&t->tqent_list, &tq->tq_delay_list);
635 t->tqent_id = rc = tq->tq_next_id;
637 t->tqent_func = func;
640 t->tqent_timer.data = (unsigned long)t;
641 t->tqent_timer.function = task_expire;
642 t->tqent_timer.expires = (unsigned long)expire_time;
643 add_timer(&t->tqent_timer);
645 ASSERT(!(t->tqent_flags & TQENT_FLAG_PREALLOC));
647 spin_unlock(&t->tqent_lock);
649 /* Spawn additional taskq threads if required. */
650 if (tq->tq_nactive == tq->tq_nthreads)
651 (void) taskq_thread_spawn(tq);
652 spin_unlock_irqrestore(&tq->tq_lock, irqflags);
655 EXPORT_SYMBOL(taskq_dispatch_delay);
658 taskq_dispatch_ent(taskq_t *tq, task_func_t func, void *arg, uint_t flags,
661 unsigned long irqflags;
665 spin_lock_irqsave_nested(&tq->tq_lock, irqflags,
668 /* Taskq being destroyed and all tasks drained */
669 if (!(tq->tq_flags & TASKQ_ACTIVE)) {
670 t->tqent_id = TASKQID_INVALID;
674 if ((flags & TQ_NOQUEUE) && (tq->tq_nactive == tq->tq_nthreads)) {
675 /* Dynamic taskq may be able to spawn another thread */
676 if (!(tq->tq_flags & TASKQ_DYNAMIC) || taskq_thread_spawn(tq) == 0)
681 spin_lock(&t->tqent_lock);
684 * Mark it as a prealloc'd task. This is important
685 * to ensure that we don't free it later.
687 t->tqent_flags |= TQENT_FLAG_PREALLOC;
689 /* Queue to the priority list instead of the pending list */
690 if (flags & TQ_FRONT)
691 list_add_tail(&t->tqent_list, &tq->tq_prio_list);
693 list_add_tail(&t->tqent_list, &tq->tq_pend_list);
695 t->tqent_id = tq->tq_next_id;
697 t->tqent_func = func;
700 t->tqent_birth = jiffies;
702 spin_unlock(&t->tqent_lock);
704 wake_up(&tq->tq_work_waitq);
706 /* Spawn additional taskq threads if required. */
707 if (tq->tq_nactive == tq->tq_nthreads)
708 (void) taskq_thread_spawn(tq);
710 spin_unlock_irqrestore(&tq->tq_lock, irqflags);
712 EXPORT_SYMBOL(taskq_dispatch_ent);
715 taskq_empty_ent(taskq_ent_t *t)
717 return (list_empty(&t->tqent_list));
719 EXPORT_SYMBOL(taskq_empty_ent);
722 taskq_init_ent(taskq_ent_t *t)
724 spin_lock_init(&t->tqent_lock);
725 init_waitqueue_head(&t->tqent_waitq);
726 init_timer(&t->tqent_timer);
727 INIT_LIST_HEAD(&t->tqent_list);
729 t->tqent_func = NULL;
732 t->tqent_taskq = NULL;
734 EXPORT_SYMBOL(taskq_init_ent);
737 * Return the next pending task, preference is given to tasks on the
738 * priority list which were dispatched with TQ_FRONT.
741 taskq_next_ent(taskq_t *tq)
743 struct list_head *list;
745 ASSERT(spin_is_locked(&tq->tq_lock));
747 if (!list_empty(&tq->tq_prio_list))
748 list = &tq->tq_prio_list;
749 else if (!list_empty(&tq->tq_pend_list))
750 list = &tq->tq_pend_list;
754 return (list_entry(list->next, taskq_ent_t, tqent_list));
758 * Spawns a new thread for the specified taskq.
761 taskq_thread_spawn_task(void *arg)
763 taskq_t *tq = (taskq_t *)arg;
766 if (taskq_thread_create(tq) == NULL) {
767 /* restore spawning count if failed */
768 spin_lock_irqsave_nested(&tq->tq_lock, flags, tq->tq_lock_class);
770 spin_unlock_irqrestore(&tq->tq_lock, flags);
775 * Spawn addition threads for dynamic taskqs (TASKQ_DYNAMIC) the current
776 * number of threads is insufficient to handle the pending tasks. These
777 * new threads must be created by the dedicated dynamic_taskq to avoid
778 * deadlocks between thread creation and memory reclaim. The system_taskq
779 * which is also a dynamic taskq cannot be safely used for this.
782 taskq_thread_spawn(taskq_t *tq)
786 if (!(tq->tq_flags & TASKQ_DYNAMIC))
789 if ((tq->tq_nthreads + tq->tq_nspawn < tq->tq_maxthreads) &&
790 (tq->tq_flags & TASKQ_ACTIVE)) {
791 spawning = (++tq->tq_nspawn);
792 taskq_dispatch(dynamic_taskq, taskq_thread_spawn_task,
800 * Threads in a dynamic taskq should only exit once it has been completely
801 * drained and no other threads are actively servicing tasks. This prevents
802 * threads from being created and destroyed more than is required.
804 * The first thread is the thread list is treated as the primary thread.
805 * There is nothing special about the primary thread but in order to avoid
806 * all the taskq pids from changing we opt to make it long running.
809 taskq_thread_should_stop(taskq_t *tq, taskq_thread_t *tqt)
811 ASSERT(spin_is_locked(&tq->tq_lock));
813 if (!(tq->tq_flags & TASKQ_DYNAMIC))
816 if (list_first_entry(&(tq->tq_thread_list), taskq_thread_t,
817 tqt_thread_list) == tqt)
821 ((tq->tq_nspawn == 0) && /* No threads are being spawned */
822 (tq->tq_nactive == 0) && /* No threads are handling tasks */
823 (tq->tq_nthreads > 1) && /* More than 1 thread is running */
824 (!taskq_next_ent(tq)) && /* There are no pending tasks */
825 (spl_taskq_thread_dynamic)); /* Dynamic taskqs are allowed */
829 taskq_thread(void *args)
831 DECLARE_WAITQUEUE(wait, current);
833 taskq_thread_t *tqt = args;
842 current->flags |= PF_NOFREEZE;
844 (void) spl_fstrans_mark();
846 sigfillset(&blocked);
847 sigprocmask(SIG_BLOCK, &blocked, NULL);
848 flush_signals(current);
850 tsd_set(taskq_tsd, tq);
851 spin_lock_irqsave_nested(&tq->tq_lock, flags, tq->tq_lock_class);
853 * If we are dynamically spawned, decrease spawning count. Note that
854 * we could be created during taskq_create, in which case we shouldn't
855 * do the decrement. But it's fine because taskq_create will reset
858 if (tq->tq_flags & TASKQ_DYNAMIC)
861 /* Immediately exit if more threads than allowed were created. */
862 if (tq->tq_nthreads >= tq->tq_maxthreads)
866 list_add_tail(&tqt->tqt_thread_list, &tq->tq_thread_list);
867 wake_up(&tq->tq_wait_waitq);
868 set_current_state(TASK_INTERRUPTIBLE);
870 while (!kthread_should_stop()) {
872 if (list_empty(&tq->tq_pend_list) &&
873 list_empty(&tq->tq_prio_list)) {
875 if (taskq_thread_should_stop(tq, tqt)) {
876 wake_up_all(&tq->tq_wait_waitq);
880 add_wait_queue_exclusive(&tq->tq_work_waitq, &wait);
881 spin_unlock_irqrestore(&tq->tq_lock, flags);
886 spin_lock_irqsave_nested(&tq->tq_lock, flags,
888 remove_wait_queue(&tq->tq_work_waitq, &wait);
890 __set_current_state(TASK_RUNNING);
893 if ((t = taskq_next_ent(tq)) != NULL) {
894 list_del_init(&t->tqent_list);
897 * In order to support recursively dispatching a
898 * preallocated taskq_ent_t, tqent_id must be
899 * stored prior to executing tqent_func.
901 tqt->tqt_id = t->tqent_id;
905 * We must store a copy of the flags prior to
906 * servicing the task (servicing a prealloc'd task
907 * returns the ownership of the tqent back to
908 * the caller of taskq_dispatch). Thus,
909 * tqent_flags _may_ change within the call.
911 tqt->tqt_flags = t->tqent_flags;
913 taskq_insert_in_order(tq, tqt);
915 spin_unlock_irqrestore(&tq->tq_lock, flags);
917 /* Perform the requested task */
918 t->tqent_func(t->tqent_arg);
920 spin_lock_irqsave_nested(&tq->tq_lock, flags,
923 list_del_init(&tqt->tqt_active_list);
924 tqt->tqt_task = NULL;
926 /* For prealloc'd tasks, we don't free anything. */
927 if (!(tqt->tqt_flags & TQENT_FLAG_PREALLOC))
931 * When the current lowest outstanding taskqid is
932 * done calculate the new lowest outstanding id
934 if (tq->tq_lowest_id == tqt->tqt_id) {
935 tq->tq_lowest_id = taskq_lowest_id(tq);
936 ASSERT3S(tq->tq_lowest_id, >, tqt->tqt_id);
939 /* Spawn additional taskq threads if required. */
940 if ((++seq_tasks) > spl_taskq_thread_sequential &&
941 taskq_thread_spawn(tq))
944 tqt->tqt_id = TASKQID_INVALID;
946 wake_up_all(&tq->tq_wait_waitq);
948 if (taskq_thread_should_stop(tq, tqt))
952 set_current_state(TASK_INTERRUPTIBLE);
956 __set_current_state(TASK_RUNNING);
958 list_del_init(&tqt->tqt_thread_list);
960 kmem_free(tqt, sizeof (taskq_thread_t));
961 spin_unlock_irqrestore(&tq->tq_lock, flags);
963 tsd_set(taskq_tsd, NULL);
968 static taskq_thread_t *
969 taskq_thread_create(taskq_t *tq)
971 static int last_used_cpu = 0;
974 tqt = kmem_alloc(sizeof (*tqt), KM_PUSHPAGE);
975 INIT_LIST_HEAD(&tqt->tqt_thread_list);
976 INIT_LIST_HEAD(&tqt->tqt_active_list);
978 tqt->tqt_id = TASKQID_INVALID;
980 tqt->tqt_thread = spl_kthread_create(taskq_thread, tqt,
982 if (tqt->tqt_thread == NULL) {
983 kmem_free(tqt, sizeof (taskq_thread_t));
987 if (spl_taskq_thread_bind) {
988 last_used_cpu = (last_used_cpu + 1) % num_online_cpus();
989 kthread_bind(tqt->tqt_thread, last_used_cpu);
992 if (spl_taskq_thread_priority)
993 set_user_nice(tqt->tqt_thread, PRIO_TO_NICE(tq->tq_pri));
995 wake_up_process(tqt->tqt_thread);
1001 taskq_create(const char *name, int nthreads, pri_t pri,
1002 int minalloc, int maxalloc, uint_t flags)
1005 taskq_thread_t *tqt;
1006 int count = 0, rc = 0, i;
1007 unsigned long irqflags;
1009 ASSERT(name != NULL);
1010 ASSERT(minalloc >= 0);
1011 ASSERT(maxalloc <= INT_MAX);
1012 ASSERT(!(flags & (TASKQ_CPR_SAFE))); /* Unsupported */
1014 /* Scale the number of threads using nthreads as a percentage */
1015 if (flags & TASKQ_THREADS_CPU_PCT) {
1016 ASSERT(nthreads <= 100);
1017 ASSERT(nthreads >= 0);
1018 nthreads = MIN(nthreads, 100);
1019 nthreads = MAX(nthreads, 0);
1020 nthreads = MAX((num_online_cpus() * nthreads) / 100, 1);
1023 tq = kmem_alloc(sizeof (*tq), KM_PUSHPAGE);
1027 spin_lock_init(&tq->tq_lock);
1028 INIT_LIST_HEAD(&tq->tq_thread_list);
1029 INIT_LIST_HEAD(&tq->tq_active_list);
1030 tq->tq_name = strdup(name);
1032 tq->tq_nthreads = 0;
1034 tq->tq_maxthreads = nthreads;
1036 tq->tq_minalloc = minalloc;
1037 tq->tq_maxalloc = maxalloc;
1039 tq->tq_flags = (flags | TASKQ_ACTIVE);
1040 tq->tq_next_id = TASKQID_INITIAL;
1041 tq->tq_lowest_id = TASKQID_INITIAL;
1042 INIT_LIST_HEAD(&tq->tq_free_list);
1043 INIT_LIST_HEAD(&tq->tq_pend_list);
1044 INIT_LIST_HEAD(&tq->tq_prio_list);
1045 INIT_LIST_HEAD(&tq->tq_delay_list);
1046 init_waitqueue_head(&tq->tq_work_waitq);
1047 init_waitqueue_head(&tq->tq_wait_waitq);
1048 tq->tq_lock_class = TQ_LOCK_GENERAL;
1049 INIT_LIST_HEAD(&tq->tq_taskqs);
1051 if (flags & TASKQ_PREPOPULATE) {
1052 spin_lock_irqsave_nested(&tq->tq_lock, irqflags,
1055 for (i = 0; i < minalloc; i++)
1056 task_done(tq, task_alloc(tq, TQ_PUSHPAGE | TQ_NEW,
1059 spin_unlock_irqrestore(&tq->tq_lock, irqflags);
1062 if ((flags & TASKQ_DYNAMIC) && spl_taskq_thread_dynamic)
1065 for (i = 0; i < nthreads; i++) {
1066 tqt = taskq_thread_create(tq);
1073 /* Wait for all threads to be started before potential destroy */
1074 wait_event(tq->tq_wait_waitq, tq->tq_nthreads == count);
1076 * taskq_thread might have touched nspawn, but we don't want them to
1077 * because they're not dynamically spawned. So we reset it to 0
1085 down_write(&tq_list_sem);
1086 tq->tq_instance = taskq_find_by_name(name) + 1;
1087 list_add_tail(&tq->tq_taskqs, &tq_list);
1088 up_write(&tq_list_sem);
1093 EXPORT_SYMBOL(taskq_create);
1096 taskq_destroy(taskq_t *tq)
1098 struct task_struct *thread;
1099 taskq_thread_t *tqt;
1101 unsigned long flags;
1104 spin_lock_irqsave_nested(&tq->tq_lock, flags, tq->tq_lock_class);
1105 tq->tq_flags &= ~TASKQ_ACTIVE;
1106 spin_unlock_irqrestore(&tq->tq_lock, flags);
1109 * When TASKQ_ACTIVE is clear new tasks may not be added nor may
1110 * new worker threads be spawned for dynamic taskq.
1112 if (dynamic_taskq != NULL)
1113 taskq_wait_outstanding(dynamic_taskq, 0);
1117 /* remove taskq from global list used by the kstats */
1118 down_write(&tq_list_sem);
1119 list_del(&tq->tq_taskqs);
1120 up_write(&tq_list_sem);
1122 spin_lock_irqsave_nested(&tq->tq_lock, flags, tq->tq_lock_class);
1123 /* wait for spawning threads to insert themselves to the list */
1124 while (tq->tq_nspawn) {
1125 spin_unlock_irqrestore(&tq->tq_lock, flags);
1126 schedule_timeout_interruptible(1);
1127 spin_lock_irqsave_nested(&tq->tq_lock, flags, tq->tq_lock_class);
1131 * Signal each thread to exit and block until it does. Each thread
1132 * is responsible for removing itself from the list and freeing its
1133 * taskq_thread_t. This allows for idle threads to opt to remove
1134 * themselves from the taskq. They can be recreated as needed.
1136 while (!list_empty(&tq->tq_thread_list)) {
1137 tqt = list_entry(tq->tq_thread_list.next,
1138 taskq_thread_t, tqt_thread_list);
1139 thread = tqt->tqt_thread;
1140 spin_unlock_irqrestore(&tq->tq_lock, flags);
1142 kthread_stop(thread);
1144 spin_lock_irqsave_nested(&tq->tq_lock, flags,
1148 while (!list_empty(&tq->tq_free_list)) {
1149 t = list_entry(tq->tq_free_list.next, taskq_ent_t, tqent_list);
1151 ASSERT(!(t->tqent_flags & TQENT_FLAG_PREALLOC));
1153 list_del_init(&t->tqent_list);
1157 ASSERT0(tq->tq_nthreads);
1158 ASSERT0(tq->tq_nalloc);
1159 ASSERT0(tq->tq_nspawn);
1160 ASSERT(list_empty(&tq->tq_thread_list));
1161 ASSERT(list_empty(&tq->tq_active_list));
1162 ASSERT(list_empty(&tq->tq_free_list));
1163 ASSERT(list_empty(&tq->tq_pend_list));
1164 ASSERT(list_empty(&tq->tq_prio_list));
1165 ASSERT(list_empty(&tq->tq_delay_list));
1167 spin_unlock_irqrestore(&tq->tq_lock, flags);
1169 strfree(tq->tq_name);
1170 kmem_free(tq, sizeof (taskq_t));
1172 EXPORT_SYMBOL(taskq_destroy);
1175 static unsigned int spl_taskq_kick = 0;
1179 * module_param_cb is introduced to take kernel_param_ops and
1180 * module_param_call is marked as obsolete. Also set and get operations
1181 * were changed to take a 'const struct kernel_param *'.
1184 #ifdef module_param_cb
1185 param_set_taskq_kick(const char *val, const struct kernel_param *kp)
1187 param_set_taskq_kick(const char *val, struct kernel_param *kp)
1193 unsigned long flags;
1195 ret = param_set_uint(val, kp);
1196 if (ret < 0 || !spl_taskq_kick)
1201 down_read(&tq_list_sem);
1202 list_for_each_entry(tq, &tq_list, tq_taskqs) {
1203 spin_lock_irqsave_nested(&tq->tq_lock, flags,
1205 /* Check if the first pending is older than 5 seconds */
1206 t = taskq_next_ent(tq);
1207 if (t && time_after(jiffies, t->tqent_birth + 5*HZ)) {
1208 (void) taskq_thread_spawn(tq);
1209 printk(KERN_INFO "spl: Kicked taskq %s/%d\n",
1210 tq->tq_name, tq->tq_instance);
1212 spin_unlock_irqrestore(&tq->tq_lock, flags);
1214 up_read(&tq_list_sem);
1218 #ifdef module_param_cb
1219 static const struct kernel_param_ops param_ops_taskq_kick = {
1220 .set = param_set_taskq_kick,
1221 .get = param_get_uint,
1223 module_param_cb(spl_taskq_kick, ¶m_ops_taskq_kick, &spl_taskq_kick, 0644);
1225 module_param_call(spl_taskq_kick, param_set_taskq_kick, param_get_uint,
1226 &spl_taskq_kick, 0644);
1228 MODULE_PARM_DESC(spl_taskq_kick,
1229 "Write nonzero to kick stuck taskqs to spawn more threads");
1232 spl_taskq_init(void)
1234 tsd_create(&taskq_tsd, NULL);
1236 system_taskq = taskq_create("spl_system_taskq", MAX(boot_ncpus, 64),
1237 maxclsyspri, boot_ncpus, INT_MAX, TASKQ_PREPOPULATE|TASKQ_DYNAMIC);
1238 if (system_taskq == NULL)
1241 dynamic_taskq = taskq_create("spl_dynamic_taskq", 1,
1242 maxclsyspri, boot_ncpus, INT_MAX, TASKQ_PREPOPULATE);
1243 if (dynamic_taskq == NULL) {
1244 taskq_destroy(system_taskq);
1249 * This is used to annotate tq_lock, so
1250 * taskq_dispatch -> taskq_thread_spawn -> taskq_dispatch
1251 * does not trigger a lockdep warning re: possible recursive locking
1253 dynamic_taskq->tq_lock_class = TQ_LOCK_DYNAMIC;
1259 spl_taskq_fini(void)
1261 taskq_destroy(dynamic_taskq);
1262 dynamic_taskq = NULL;
1264 taskq_destroy(system_taskq);
1265 system_taskq = NULL;
1267 tsd_destroy(&taskq_tsd);