2 * Copyright 2015 Advanced Micro Devices, Inc.
4 * Permission is hereby granted, free of charge, to any person obtaining a
5 * copy of this software and associated documentation files (the "Software"),
6 * to deal in the Software without restriction, including without limitation
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9 * Software is furnished to do so, subject to the following conditions:
11 * The above copyright notice and this permission notice shall be included in
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14 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
15 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
16 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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19 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
20 * OTHER DEALINGS IN THE SOFTWARE.
27 * The GPU scheduler provides entities which allow userspace to push jobs
28 * into software queues which are then scheduled on a hardware run queue.
29 * The software queues have a priority among them. The scheduler selects the entities
30 * from the run queue using a FIFO. The scheduler provides dependency handling
31 * features among jobs. The driver is supposed to provide callback functions for
32 * backend operations to the scheduler like submitting a job to hardware run queue,
33 * returning the dependencies of a job etc.
35 * The organisation of the scheduler is the following:
37 * 1. Each hw run queue has one scheduler
38 * 2. Each scheduler has multiple run queues with different priorities
39 * (e.g., HIGH_HW,HIGH_SW, KERNEL, NORMAL)
40 * 3. Each scheduler run queue has a queue of entities to schedule
41 * 4. Entities themselves maintain a queue of jobs that will be scheduled on
44 * The jobs in a entity are always scheduled in the order that they were pushed.
47 #include <linux/kthread.h>
48 #include <linux/wait.h>
49 #include <linux/sched.h>
50 #include <uapi/linux/sched/types.h>
52 #include <drm/gpu_scheduler.h>
53 #include <drm/spsc_queue.h>
55 #define CREATE_TRACE_POINTS
56 #include "gpu_scheduler_trace.h"
58 #define to_drm_sched_job(sched_job) \
59 container_of((sched_job), struct drm_sched_job, queue_node)
61 static void drm_sched_process_job(struct dma_fence *f, struct dma_fence_cb *cb);
64 * drm_sched_rq_init - initialize a given run queue struct
66 * @rq: scheduler run queue
68 * Initializes a scheduler runqueue.
70 static void drm_sched_rq_init(struct drm_gpu_scheduler *sched,
71 struct drm_sched_rq *rq)
73 spin_lock_init(&rq->lock);
74 INIT_LIST_HEAD(&rq->entities);
75 rq->current_entity = NULL;
80 * drm_sched_rq_add_entity - add an entity
82 * @rq: scheduler run queue
83 * @entity: scheduler entity
85 * Adds a scheduler entity to the run queue.
87 void drm_sched_rq_add_entity(struct drm_sched_rq *rq,
88 struct drm_sched_entity *entity)
90 if (!list_empty(&entity->list))
93 list_add_tail(&entity->list, &rq->entities);
94 spin_unlock(&rq->lock);
98 * drm_sched_rq_remove_entity - remove an entity
100 * @rq: scheduler run queue
101 * @entity: scheduler entity
103 * Removes a scheduler entity from the run queue.
105 void drm_sched_rq_remove_entity(struct drm_sched_rq *rq,
106 struct drm_sched_entity *entity)
108 if (list_empty(&entity->list))
110 spin_lock(&rq->lock);
111 list_del_init(&entity->list);
112 if (rq->current_entity == entity)
113 rq->current_entity = NULL;
114 spin_unlock(&rq->lock);
118 * drm_sched_rq_select_entity - Select an entity which could provide a job to run
120 * @rq: scheduler run queue to check.
122 * Try to find a ready entity, returns NULL if none found.
124 static struct drm_sched_entity *
125 drm_sched_rq_select_entity(struct drm_sched_rq *rq)
127 struct drm_sched_entity *entity;
129 spin_lock(&rq->lock);
131 entity = rq->current_entity;
133 list_for_each_entry_continue(entity, &rq->entities, list) {
134 if (drm_sched_entity_is_ready(entity)) {
135 rq->current_entity = entity;
136 spin_unlock(&rq->lock);
142 list_for_each_entry(entity, &rq->entities, list) {
144 if (drm_sched_entity_is_ready(entity)) {
145 rq->current_entity = entity;
146 spin_unlock(&rq->lock);
150 if (entity == rq->current_entity)
154 spin_unlock(&rq->lock);
160 * drm_sched_dependency_optimized
162 * @fence: the dependency fence
163 * @entity: the entity which depends on the above fence
165 * Returns true if the dependency can be optimized and false otherwise
167 bool drm_sched_dependency_optimized(struct dma_fence* fence,
168 struct drm_sched_entity *entity)
170 struct drm_gpu_scheduler *sched = entity->rq->sched;
171 struct drm_sched_fence *s_fence;
173 if (!fence || dma_fence_is_signaled(fence))
175 if (fence->context == entity->fence_context)
177 s_fence = to_drm_sched_fence(fence);
178 if (s_fence && s_fence->sched == sched)
183 EXPORT_SYMBOL(drm_sched_dependency_optimized);
186 * drm_sched_start_timeout - start timeout for reset worker
188 * @sched: scheduler instance to start the worker for
190 * Start the timeout for the given scheduler.
192 static void drm_sched_start_timeout(struct drm_gpu_scheduler *sched)
194 if (sched->timeout != MAX_SCHEDULE_TIMEOUT &&
195 !list_empty(&sched->ring_mirror_list))
196 schedule_delayed_work(&sched->work_tdr, sched->timeout);
200 * drm_sched_fault - immediately start timeout handler
202 * @sched: scheduler where the timeout handling should be started.
204 * Start timeout handling immediately when the driver detects a hardware fault.
206 void drm_sched_fault(struct drm_gpu_scheduler *sched)
208 mod_delayed_work(system_wq, &sched->work_tdr, 0);
210 EXPORT_SYMBOL(drm_sched_fault);
213 * drm_sched_suspend_timeout - Suspend scheduler job timeout
215 * @sched: scheduler instance for which to suspend the timeout
217 * Suspend the delayed work timeout for the scheduler. This is done by
218 * modifying the delayed work timeout to an arbitrary large value,
219 * MAX_SCHEDULE_TIMEOUT in this case. Note that this function can be
220 * called from an IRQ context.
222 * Returns the timeout remaining
225 unsigned long drm_sched_suspend_timeout(struct drm_gpu_scheduler *sched)
227 unsigned long sched_timeout, now = jiffies;
229 sched_timeout = sched->work_tdr.timer.expires;
232 * Modify the timeout to an arbitrarily large value. This also prevents
233 * the timeout to be restarted when new submissions arrive
235 if (mod_delayed_work(system_wq, &sched->work_tdr, MAX_SCHEDULE_TIMEOUT)
236 && time_after(sched_timeout, now))
237 return sched_timeout - now;
239 return sched->timeout;
241 EXPORT_SYMBOL(drm_sched_suspend_timeout);
244 * drm_sched_resume_timeout - Resume scheduler job timeout
246 * @sched: scheduler instance for which to resume the timeout
247 * @remaining: remaining timeout
249 * Resume the delayed work timeout for the scheduler. Note that
250 * this function can be called from an IRQ context.
252 void drm_sched_resume_timeout(struct drm_gpu_scheduler *sched,
253 unsigned long remaining)
257 spin_lock_irqsave(&sched->job_list_lock, flags);
259 if (list_empty(&sched->ring_mirror_list))
260 cancel_delayed_work(&sched->work_tdr);
262 mod_delayed_work(system_wq, &sched->work_tdr, remaining);
264 spin_unlock_irqrestore(&sched->job_list_lock, flags);
266 EXPORT_SYMBOL(drm_sched_resume_timeout);
268 static void drm_sched_job_begin(struct drm_sched_job *s_job)
270 struct drm_gpu_scheduler *sched = s_job->sched;
273 spin_lock_irqsave(&sched->job_list_lock, flags);
274 list_add_tail(&s_job->node, &sched->ring_mirror_list);
275 drm_sched_start_timeout(sched);
276 spin_unlock_irqrestore(&sched->job_list_lock, flags);
279 static void drm_sched_job_timedout(struct work_struct *work)
281 struct drm_gpu_scheduler *sched;
282 struct drm_sched_job *job;
285 sched = container_of(work, struct drm_gpu_scheduler, work_tdr.work);
286 job = list_first_entry_or_null(&sched->ring_mirror_list,
287 struct drm_sched_job, node);
290 job->sched->ops->timedout_job(job);
293 * Guilty job did complete and hence needs to be manually removed
294 * See drm_sched_stop doc.
296 if (sched->free_guilty) {
297 job->sched->ops->free_job(job);
298 sched->free_guilty = false;
302 spin_lock_irqsave(&sched->job_list_lock, flags);
303 drm_sched_start_timeout(sched);
304 spin_unlock_irqrestore(&sched->job_list_lock, flags);
308 * drm_sched_increase_karma - Update sched_entity guilty flag
310 * @bad: The job guilty of time out
312 * Increment on every hang caused by the 'bad' job. If this exceeds the hang
313 * limit of the scheduler then the respective sched entity is marked guilty and
314 * jobs from it will not be scheduled further
316 void drm_sched_increase_karma(struct drm_sched_job *bad)
319 struct drm_sched_entity *tmp;
320 struct drm_sched_entity *entity;
321 struct drm_gpu_scheduler *sched = bad->sched;
323 /* don't increase @bad's karma if it's from KERNEL RQ,
324 * because sometimes GPU hang would cause kernel jobs (like VM updating jobs)
325 * corrupt but keep in mind that kernel jobs always considered good.
327 if (bad->s_priority != DRM_SCHED_PRIORITY_KERNEL) {
328 atomic_inc(&bad->karma);
329 for (i = DRM_SCHED_PRIORITY_MIN; i < DRM_SCHED_PRIORITY_KERNEL;
331 struct drm_sched_rq *rq = &sched->sched_rq[i];
333 spin_lock(&rq->lock);
334 list_for_each_entry_safe(entity, tmp, &rq->entities, list) {
335 if (bad->s_fence->scheduled.context ==
336 entity->fence_context) {
337 if (atomic_read(&bad->karma) >
338 bad->sched->hang_limit)
340 atomic_set(entity->guilty, 1);
344 spin_unlock(&rq->lock);
345 if (&entity->list != &rq->entities)
350 EXPORT_SYMBOL(drm_sched_increase_karma);
353 * drm_sched_stop - stop the scheduler
355 * @sched: scheduler instance
356 * @bad: job which caused the time out
358 * Stop the scheduler and also removes and frees all completed jobs.
359 * Note: bad job will not be freed as it might be used later and so it's
360 * callers responsibility to release it manually if it's not part of the
361 * mirror list any more.
364 void drm_sched_stop(struct drm_gpu_scheduler *sched, struct drm_sched_job *bad)
366 struct drm_sched_job *s_job, *tmp;
369 kthread_park(sched->thread);
372 * Iterate the job list from later to earlier one and either deactive
373 * their HW callbacks or remove them from mirror list if they already
375 * This iteration is thread safe as sched thread is stopped.
377 list_for_each_entry_safe_reverse(s_job, tmp, &sched->ring_mirror_list, node) {
378 if (s_job->s_fence->parent &&
379 dma_fence_remove_callback(s_job->s_fence->parent,
381 atomic_dec(&sched->hw_rq_count);
384 * remove job from ring_mirror_list.
385 * Locking here is for concurrent resume timeout
387 spin_lock_irqsave(&sched->job_list_lock, flags);
388 list_del_init(&s_job->node);
389 spin_unlock_irqrestore(&sched->job_list_lock, flags);
392 * Wait for job's HW fence callback to finish using s_job
393 * before releasing it.
395 * Job is still alive so fence refcount at least 1
397 dma_fence_wait(&s_job->s_fence->finished, false);
400 * We must keep bad job alive for later use during
401 * recovery by some of the drivers but leave a hint
402 * that the guilty job must be released.
405 sched->ops->free_job(s_job);
407 sched->free_guilty = true;
412 * Stop pending timer in flight as we rearm it in drm_sched_start. This
413 * avoids the pending timeout work in progress to fire right away after
414 * this TDR finished and before the newly restarted jobs had a
415 * chance to complete.
417 cancel_delayed_work(&sched->work_tdr);
420 EXPORT_SYMBOL(drm_sched_stop);
423 * drm_sched_job_recovery - recover jobs after a reset
425 * @sched: scheduler instance
426 * @full_recovery: proceed with complete sched restart
429 void drm_sched_start(struct drm_gpu_scheduler *sched, bool full_recovery)
431 struct drm_sched_job *s_job, *tmp;
436 * Locking the list is not required here as the sched thread is parked
437 * so no new jobs are being inserted or removed. Also concurrent
438 * GPU recovers can't run in parallel.
440 list_for_each_entry_safe(s_job, tmp, &sched->ring_mirror_list, node) {
441 struct dma_fence *fence = s_job->s_fence->parent;
443 atomic_inc(&sched->hw_rq_count);
449 r = dma_fence_add_callback(fence, &s_job->cb,
450 drm_sched_process_job);
452 drm_sched_process_job(fence, &s_job->cb);
454 DRM_ERROR("fence add callback failed (%d)\n",
457 drm_sched_process_job(NULL, &s_job->cb);
461 spin_lock_irqsave(&sched->job_list_lock, flags);
462 drm_sched_start_timeout(sched);
463 spin_unlock_irqrestore(&sched->job_list_lock, flags);
466 kthread_unpark(sched->thread);
468 EXPORT_SYMBOL(drm_sched_start);
471 * drm_sched_resubmit_jobs - helper to relunch job from mirror ring list
473 * @sched: scheduler instance
476 void drm_sched_resubmit_jobs(struct drm_gpu_scheduler *sched)
478 struct drm_sched_job *s_job, *tmp;
479 uint64_t guilty_context;
480 bool found_guilty = false;
481 struct dma_fence *fence;
483 list_for_each_entry_safe(s_job, tmp, &sched->ring_mirror_list, node) {
484 struct drm_sched_fence *s_fence = s_job->s_fence;
486 if (!found_guilty && atomic_read(&s_job->karma) > sched->hang_limit) {
488 guilty_context = s_job->s_fence->scheduled.context;
491 if (found_guilty && s_job->s_fence->scheduled.context == guilty_context)
492 dma_fence_set_error(&s_fence->finished, -ECANCELED);
494 dma_fence_put(s_job->s_fence->parent);
495 fence = sched->ops->run_job(s_job);
497 if (IS_ERR_OR_NULL(fence)) {
498 s_job->s_fence->parent = NULL;
499 dma_fence_set_error(&s_fence->finished, PTR_ERR(fence));
501 s_job->s_fence->parent = fence;
507 EXPORT_SYMBOL(drm_sched_resubmit_jobs);
510 * drm_sched_job_init - init a scheduler job
512 * @job: scheduler job to init
513 * @entity: scheduler entity to use
514 * @owner: job owner for debugging
516 * Refer to drm_sched_entity_push_job() documentation
517 * for locking considerations.
519 * Returns 0 for success, negative error code otherwise.
521 int drm_sched_job_init(struct drm_sched_job *job,
522 struct drm_sched_entity *entity,
525 struct drm_gpu_scheduler *sched;
527 drm_sched_entity_select_rq(entity);
531 sched = entity->rq->sched;
534 job->entity = entity;
535 job->s_priority = entity->rq - sched->sched_rq;
536 job->s_fence = drm_sched_fence_create(entity, owner);
539 job->id = atomic64_inc_return(&sched->job_id_count);
541 INIT_LIST_HEAD(&job->node);
545 EXPORT_SYMBOL(drm_sched_job_init);
548 * drm_sched_job_cleanup - clean up scheduler job resources
550 * @job: scheduler job to clean up
552 void drm_sched_job_cleanup(struct drm_sched_job *job)
554 dma_fence_put(&job->s_fence->finished);
557 EXPORT_SYMBOL(drm_sched_job_cleanup);
560 * drm_sched_ready - is the scheduler ready
562 * @sched: scheduler instance
564 * Return true if we can push more jobs to the hw, otherwise false.
566 static bool drm_sched_ready(struct drm_gpu_scheduler *sched)
568 return atomic_read(&sched->hw_rq_count) <
569 sched->hw_submission_limit;
573 * drm_sched_wakeup - Wake up the scheduler when it is ready
575 * @sched: scheduler instance
578 void drm_sched_wakeup(struct drm_gpu_scheduler *sched)
580 if (drm_sched_ready(sched))
581 wake_up_interruptible(&sched->wake_up_worker);
585 * drm_sched_select_entity - Select next entity to process
587 * @sched: scheduler instance
589 * Returns the entity to process or NULL if none are found.
591 static struct drm_sched_entity *
592 drm_sched_select_entity(struct drm_gpu_scheduler *sched)
594 struct drm_sched_entity *entity;
597 if (!drm_sched_ready(sched))
600 /* Kernel run queue has higher priority than normal run queue*/
601 for (i = DRM_SCHED_PRIORITY_MAX - 1; i >= DRM_SCHED_PRIORITY_MIN; i--) {
602 entity = drm_sched_rq_select_entity(&sched->sched_rq[i]);
611 * drm_sched_process_job - process a job
614 * @cb: fence callbacks
616 * Called after job has finished execution.
618 static void drm_sched_process_job(struct dma_fence *f, struct dma_fence_cb *cb)
620 struct drm_sched_job *s_job = container_of(cb, struct drm_sched_job, cb);
621 struct drm_sched_fence *s_fence = s_job->s_fence;
622 struct drm_gpu_scheduler *sched = s_fence->sched;
624 atomic_dec(&sched->hw_rq_count);
625 atomic_dec(&sched->num_jobs);
627 trace_drm_sched_process_job(s_fence);
629 drm_sched_fence_finished(s_fence);
630 wake_up_interruptible(&sched->wake_up_worker);
634 * drm_sched_cleanup_jobs - destroy finished jobs
636 * @sched: scheduler instance
638 * Remove all finished jobs from the mirror list and destroy them.
640 static void drm_sched_cleanup_jobs(struct drm_gpu_scheduler *sched)
644 /* Don't destroy jobs while the timeout worker is running */
645 if (sched->timeout != MAX_SCHEDULE_TIMEOUT &&
646 !cancel_delayed_work(&sched->work_tdr))
650 while (!list_empty(&sched->ring_mirror_list)) {
651 struct drm_sched_job *job;
653 job = list_first_entry(&sched->ring_mirror_list,
654 struct drm_sched_job, node);
655 if (!dma_fence_is_signaled(&job->s_fence->finished))
658 spin_lock_irqsave(&sched->job_list_lock, flags);
659 /* remove job from ring_mirror_list */
660 list_del_init(&job->node);
661 spin_unlock_irqrestore(&sched->job_list_lock, flags);
663 sched->ops->free_job(job);
666 /* queue timeout for next job */
667 spin_lock_irqsave(&sched->job_list_lock, flags);
668 drm_sched_start_timeout(sched);
669 spin_unlock_irqrestore(&sched->job_list_lock, flags);
674 * drm_sched_blocked - check if the scheduler is blocked
676 * @sched: scheduler instance
678 * Returns true if blocked, otherwise false.
680 static bool drm_sched_blocked(struct drm_gpu_scheduler *sched)
682 if (kthread_should_park()) {
691 * drm_sched_main - main scheduler thread
693 * @param: scheduler instance
697 static int drm_sched_main(void *param)
699 struct sched_param sparam = {.sched_priority = 1};
700 struct drm_gpu_scheduler *sched = (struct drm_gpu_scheduler *)param;
703 sched_setscheduler(current, SCHED_FIFO, &sparam);
705 while (!kthread_should_stop()) {
706 struct drm_sched_entity *entity = NULL;
707 struct drm_sched_fence *s_fence;
708 struct drm_sched_job *sched_job;
709 struct dma_fence *fence;
711 wait_event_interruptible(sched->wake_up_worker,
712 (drm_sched_cleanup_jobs(sched),
713 (!drm_sched_blocked(sched) &&
714 (entity = drm_sched_select_entity(sched))) ||
715 kthread_should_stop()));
720 sched_job = drm_sched_entity_pop_job(entity);
724 s_fence = sched_job->s_fence;
726 atomic_inc(&sched->hw_rq_count);
727 drm_sched_job_begin(sched_job);
729 fence = sched->ops->run_job(sched_job);
730 drm_sched_fence_scheduled(s_fence);
732 if (!IS_ERR_OR_NULL(fence)) {
733 s_fence->parent = dma_fence_get(fence);
734 r = dma_fence_add_callback(fence, &sched_job->cb,
735 drm_sched_process_job);
737 drm_sched_process_job(fence, &sched_job->cb);
739 DRM_ERROR("fence add callback failed (%d)\n",
741 dma_fence_put(fence);
744 dma_fence_set_error(&s_fence->finished, PTR_ERR(fence));
745 drm_sched_process_job(NULL, &sched_job->cb);
748 wake_up(&sched->job_scheduled);
754 * drm_sched_init - Init a gpu scheduler instance
756 * @sched: scheduler instance
757 * @ops: backend operations for this scheduler
758 * @hw_submission: number of hw submissions that can be in flight
759 * @hang_limit: number of times to allow a job to hang before dropping it
760 * @timeout: timeout value in jiffies for the scheduler
761 * @name: name used for debugging
763 * Return 0 on success, otherwise error code.
765 int drm_sched_init(struct drm_gpu_scheduler *sched,
766 const struct drm_sched_backend_ops *ops,
767 unsigned hw_submission,
774 sched->hw_submission_limit = hw_submission;
776 sched->timeout = timeout;
777 sched->hang_limit = hang_limit;
778 for (i = DRM_SCHED_PRIORITY_MIN; i < DRM_SCHED_PRIORITY_MAX; i++)
779 drm_sched_rq_init(sched, &sched->sched_rq[i]);
781 init_waitqueue_head(&sched->wake_up_worker);
782 init_waitqueue_head(&sched->job_scheduled);
783 INIT_LIST_HEAD(&sched->ring_mirror_list);
784 spin_lock_init(&sched->job_list_lock);
785 atomic_set(&sched->hw_rq_count, 0);
786 INIT_DELAYED_WORK(&sched->work_tdr, drm_sched_job_timedout);
787 atomic_set(&sched->num_jobs, 0);
788 atomic64_set(&sched->job_id_count, 0);
790 /* Each scheduler will run on a seperate kernel thread */
791 sched->thread = kthread_run(drm_sched_main, sched, sched->name);
792 if (IS_ERR(sched->thread)) {
793 ret = PTR_ERR(sched->thread);
794 sched->thread = NULL;
795 DRM_ERROR("Failed to create scheduler for %s.\n", name);
802 EXPORT_SYMBOL(drm_sched_init);
805 * drm_sched_fini - Destroy a gpu scheduler
807 * @sched: scheduler instance
809 * Tears down and cleans up the scheduler.
811 void drm_sched_fini(struct drm_gpu_scheduler *sched)
814 kthread_stop(sched->thread);
816 sched->ready = false;
818 EXPORT_SYMBOL(drm_sched_fini);