2 * Copyright 2015 Advanced Micro Devices, Inc.
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5 * copy of this software and associated documentation files (the "Software"),
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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,
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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 /* job_finish is called after hw fence signaled
270 static void drm_sched_job_finish(struct work_struct *work)
272 struct drm_sched_job *s_job = container_of(work, struct drm_sched_job,
274 struct drm_gpu_scheduler *sched = s_job->sched;
278 * Canceling the timeout without removing our job from the ring mirror
279 * list is safe, as we will only end up in this worker if our jobs
280 * finished fence has been signaled. So even if some another worker
281 * manages to find this job as the next job in the list, the fence
282 * signaled check below will prevent the timeout to be restarted.
284 cancel_delayed_work_sync(&sched->work_tdr);
286 spin_lock_irqsave(&sched->job_list_lock, flags);
287 /* queue TDR for next job */
288 drm_sched_start_timeout(sched);
289 spin_unlock_irqrestore(&sched->job_list_lock, flags);
291 sched->ops->free_job(s_job);
294 static void drm_sched_job_begin(struct drm_sched_job *s_job)
296 struct drm_gpu_scheduler *sched = s_job->sched;
299 spin_lock_irqsave(&sched->job_list_lock, flags);
300 list_add_tail(&s_job->node, &sched->ring_mirror_list);
301 drm_sched_start_timeout(sched);
302 spin_unlock_irqrestore(&sched->job_list_lock, flags);
305 static void drm_sched_job_timedout(struct work_struct *work)
307 struct drm_gpu_scheduler *sched;
308 struct drm_sched_job *job;
311 sched = container_of(work, struct drm_gpu_scheduler, work_tdr.work);
312 job = list_first_entry_or_null(&sched->ring_mirror_list,
313 struct drm_sched_job, node);
316 job->sched->ops->timedout_job(job);
318 spin_lock_irqsave(&sched->job_list_lock, flags);
319 drm_sched_start_timeout(sched);
320 spin_unlock_irqrestore(&sched->job_list_lock, flags);
324 * drm_sched_increase_karma - Update sched_entity guilty flag
326 * @bad: The job guilty of time out
328 * Increment on every hang caused by the 'bad' job. If this exceeds the hang
329 * limit of the scheduler then the respective sched entity is marked guilty and
330 * jobs from it will not be scheduled further
332 void drm_sched_increase_karma(struct drm_sched_job *bad)
335 struct drm_sched_entity *tmp;
336 struct drm_sched_entity *entity;
337 struct drm_gpu_scheduler *sched = bad->sched;
339 /* don't increase @bad's karma if it's from KERNEL RQ,
340 * because sometimes GPU hang would cause kernel jobs (like VM updating jobs)
341 * corrupt but keep in mind that kernel jobs always considered good.
343 if (bad->s_priority != DRM_SCHED_PRIORITY_KERNEL) {
344 atomic_inc(&bad->karma);
345 for (i = DRM_SCHED_PRIORITY_MIN; i < DRM_SCHED_PRIORITY_KERNEL;
347 struct drm_sched_rq *rq = &sched->sched_rq[i];
349 spin_lock(&rq->lock);
350 list_for_each_entry_safe(entity, tmp, &rq->entities, list) {
351 if (bad->s_fence->scheduled.context ==
352 entity->fence_context) {
353 if (atomic_read(&bad->karma) >
354 bad->sched->hang_limit)
356 atomic_set(entity->guilty, 1);
360 spin_unlock(&rq->lock);
361 if (&entity->list != &rq->entities)
366 EXPORT_SYMBOL(drm_sched_increase_karma);
369 * drm_sched_stop - stop the scheduler
371 * @sched: scheduler instance
374 void drm_sched_stop(struct drm_gpu_scheduler *sched)
376 struct drm_sched_job *s_job;
378 struct dma_fence *last_fence = NULL;
380 kthread_park(sched->thread);
383 * Verify all the signaled jobs in mirror list are removed from the ring
384 * by waiting for the latest job to enter the list. This should insure that
385 * also all the previous jobs that were in flight also already singaled
386 * and removed from the list.
388 spin_lock_irqsave(&sched->job_list_lock, flags);
389 list_for_each_entry_reverse(s_job, &sched->ring_mirror_list, node) {
390 if (s_job->s_fence->parent &&
391 dma_fence_remove_callback(s_job->s_fence->parent,
393 dma_fence_put(s_job->s_fence->parent);
394 s_job->s_fence->parent = NULL;
395 atomic_dec(&sched->hw_rq_count);
397 last_fence = dma_fence_get(&s_job->s_fence->finished);
401 spin_unlock_irqrestore(&sched->job_list_lock, flags);
404 dma_fence_wait(last_fence, false);
405 dma_fence_put(last_fence);
409 EXPORT_SYMBOL(drm_sched_stop);
412 * drm_sched_job_recovery - recover jobs after a reset
414 * @sched: scheduler instance
417 void drm_sched_start(struct drm_gpu_scheduler *sched, bool full_recovery)
419 struct drm_sched_job *s_job, *tmp;
426 * Locking the list is not required here as the sched thread is parked
427 * so no new jobs are being pushed in to HW and in drm_sched_stop we
428 * flushed all the jobs who were still in mirror list but who already
429 * signaled and removed them self from the list. Also concurrent
430 * GPU recovers can't run in parallel.
432 list_for_each_entry_safe(s_job, tmp, &sched->ring_mirror_list, node) {
433 struct dma_fence *fence = s_job->s_fence->parent;
436 r = dma_fence_add_callback(fence, &s_job->cb,
437 drm_sched_process_job);
439 drm_sched_process_job(fence, &s_job->cb);
441 DRM_ERROR("fence add callback failed (%d)\n",
444 drm_sched_process_job(NULL, &s_job->cb);
447 drm_sched_start_timeout(sched);
450 kthread_unpark(sched->thread);
452 EXPORT_SYMBOL(drm_sched_start);
455 * drm_sched_resubmit_jobs - helper to relunch job from mirror ring list
457 * @sched: scheduler instance
460 void drm_sched_resubmit_jobs(struct drm_gpu_scheduler *sched)
462 struct drm_sched_job *s_job, *tmp;
463 uint64_t guilty_context;
464 bool found_guilty = false;
466 /*TODO DO we need spinlock here ? */
467 list_for_each_entry_safe(s_job, tmp, &sched->ring_mirror_list, node) {
468 struct drm_sched_fence *s_fence = s_job->s_fence;
470 if (!found_guilty && atomic_read(&s_job->karma) > sched->hang_limit) {
472 guilty_context = s_job->s_fence->scheduled.context;
475 if (found_guilty && s_job->s_fence->scheduled.context == guilty_context)
476 dma_fence_set_error(&s_fence->finished, -ECANCELED);
478 s_job->s_fence->parent = sched->ops->run_job(s_job);
479 atomic_inc(&sched->hw_rq_count);
482 EXPORT_SYMBOL(drm_sched_resubmit_jobs);
485 * drm_sched_job_init - init a scheduler job
487 * @job: scheduler job to init
488 * @entity: scheduler entity to use
489 * @owner: job owner for debugging
491 * Refer to drm_sched_entity_push_job() documentation
492 * for locking considerations.
494 * Returns 0 for success, negative error code otherwise.
496 int drm_sched_job_init(struct drm_sched_job *job,
497 struct drm_sched_entity *entity,
500 struct drm_gpu_scheduler *sched;
502 drm_sched_entity_select_rq(entity);
506 sched = entity->rq->sched;
509 job->entity = entity;
510 job->s_priority = entity->rq - sched->sched_rq;
511 job->s_fence = drm_sched_fence_create(entity, owner);
514 job->id = atomic64_inc_return(&sched->job_id_count);
516 INIT_WORK(&job->finish_work, drm_sched_job_finish);
517 INIT_LIST_HEAD(&job->node);
521 EXPORT_SYMBOL(drm_sched_job_init);
524 * drm_sched_job_cleanup - clean up scheduler job resources
526 * @job: scheduler job to clean up
528 void drm_sched_job_cleanup(struct drm_sched_job *job)
530 dma_fence_put(&job->s_fence->finished);
533 EXPORT_SYMBOL(drm_sched_job_cleanup);
536 * drm_sched_ready - is the scheduler ready
538 * @sched: scheduler instance
540 * Return true if we can push more jobs to the hw, otherwise false.
542 static bool drm_sched_ready(struct drm_gpu_scheduler *sched)
544 return atomic_read(&sched->hw_rq_count) <
545 sched->hw_submission_limit;
549 * drm_sched_wakeup - Wake up the scheduler when it is ready
551 * @sched: scheduler instance
554 void drm_sched_wakeup(struct drm_gpu_scheduler *sched)
556 if (drm_sched_ready(sched))
557 wake_up_interruptible(&sched->wake_up_worker);
561 * drm_sched_select_entity - Select next entity to process
563 * @sched: scheduler instance
565 * Returns the entity to process or NULL if none are found.
567 static struct drm_sched_entity *
568 drm_sched_select_entity(struct drm_gpu_scheduler *sched)
570 struct drm_sched_entity *entity;
573 if (!drm_sched_ready(sched))
576 /* Kernel run queue has higher priority than normal run queue*/
577 for (i = DRM_SCHED_PRIORITY_MAX - 1; i >= DRM_SCHED_PRIORITY_MIN; i--) {
578 entity = drm_sched_rq_select_entity(&sched->sched_rq[i]);
587 * drm_sched_process_job - process a job
590 * @cb: fence callbacks
592 * Called after job has finished execution.
594 static void drm_sched_process_job(struct dma_fence *f, struct dma_fence_cb *cb)
596 struct drm_sched_job *s_job = container_of(cb, struct drm_sched_job, cb);
597 struct drm_sched_fence *s_fence = s_job->s_fence;
598 struct drm_gpu_scheduler *sched = s_fence->sched;
601 cancel_delayed_work(&sched->work_tdr);
603 atomic_dec(&sched->hw_rq_count);
604 atomic_dec(&sched->num_jobs);
606 spin_lock_irqsave(&sched->job_list_lock, flags);
607 /* remove job from ring_mirror_list */
608 list_del_init(&s_job->node);
609 spin_unlock_irqrestore(&sched->job_list_lock, flags);
611 drm_sched_fence_finished(s_fence);
613 trace_drm_sched_process_job(s_fence);
614 wake_up_interruptible(&sched->wake_up_worker);
616 schedule_work(&s_job->finish_work);
620 * drm_sched_blocked - check if the scheduler is blocked
622 * @sched: scheduler instance
624 * Returns true if blocked, otherwise false.
626 static bool drm_sched_blocked(struct drm_gpu_scheduler *sched)
628 if (kthread_should_park()) {
637 * drm_sched_main - main scheduler thread
639 * @param: scheduler instance
643 static int drm_sched_main(void *param)
645 struct sched_param sparam = {.sched_priority = 1};
646 struct drm_gpu_scheduler *sched = (struct drm_gpu_scheduler *)param;
649 sched_setscheduler(current, SCHED_FIFO, &sparam);
651 while (!kthread_should_stop()) {
652 struct drm_sched_entity *entity = NULL;
653 struct drm_sched_fence *s_fence;
654 struct drm_sched_job *sched_job;
655 struct dma_fence *fence;
657 wait_event_interruptible(sched->wake_up_worker,
658 (!drm_sched_blocked(sched) &&
659 (entity = drm_sched_select_entity(sched))) ||
660 kthread_should_stop());
665 sched_job = drm_sched_entity_pop_job(entity);
669 s_fence = sched_job->s_fence;
671 atomic_inc(&sched->hw_rq_count);
672 drm_sched_job_begin(sched_job);
674 fence = sched->ops->run_job(sched_job);
675 drm_sched_fence_scheduled(s_fence);
678 s_fence->parent = dma_fence_get(fence);
679 r = dma_fence_add_callback(fence, &sched_job->cb,
680 drm_sched_process_job);
682 drm_sched_process_job(fence, &sched_job->cb);
684 DRM_ERROR("fence add callback failed (%d)\n",
686 dma_fence_put(fence);
688 drm_sched_process_job(NULL, &sched_job->cb);
690 wake_up(&sched->job_scheduled);
696 * drm_sched_init - Init a gpu scheduler instance
698 * @sched: scheduler instance
699 * @ops: backend operations for this scheduler
700 * @hw_submission: number of hw submissions that can be in flight
701 * @hang_limit: number of times to allow a job to hang before dropping it
702 * @timeout: timeout value in jiffies for the scheduler
703 * @name: name used for debugging
705 * Return 0 on success, otherwise error code.
707 int drm_sched_init(struct drm_gpu_scheduler *sched,
708 const struct drm_sched_backend_ops *ops,
709 unsigned hw_submission,
716 sched->hw_submission_limit = hw_submission;
718 sched->timeout = timeout;
719 sched->hang_limit = hang_limit;
720 for (i = DRM_SCHED_PRIORITY_MIN; i < DRM_SCHED_PRIORITY_MAX; i++)
721 drm_sched_rq_init(sched, &sched->sched_rq[i]);
723 init_waitqueue_head(&sched->wake_up_worker);
724 init_waitqueue_head(&sched->job_scheduled);
725 INIT_LIST_HEAD(&sched->ring_mirror_list);
726 spin_lock_init(&sched->job_list_lock);
727 atomic_set(&sched->hw_rq_count, 0);
728 INIT_DELAYED_WORK(&sched->work_tdr, drm_sched_job_timedout);
729 atomic_set(&sched->num_jobs, 0);
730 atomic64_set(&sched->job_id_count, 0);
732 /* Each scheduler will run on a seperate kernel thread */
733 sched->thread = kthread_run(drm_sched_main, sched, sched->name);
734 if (IS_ERR(sched->thread)) {
735 ret = PTR_ERR(sched->thread);
736 sched->thread = NULL;
737 DRM_ERROR("Failed to create scheduler for %s.\n", name);
744 EXPORT_SYMBOL(drm_sched_init);
747 * drm_sched_fini - Destroy a gpu scheduler
749 * @sched: scheduler instance
751 * Tears down and cleans up the scheduler.
753 void drm_sched_fini(struct drm_gpu_scheduler *sched)
756 kthread_stop(sched->thread);
758 sched->ready = false;
760 EXPORT_SYMBOL(drm_sched_fini);