2 * Copyright 2015 Advanced Micro Devices, Inc.
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24 #ifndef _DRM_GPU_SCHEDULER_H_
25 #define _DRM_GPU_SCHEDULER_H_
27 #include <drm/spsc_queue.h>
28 #include <linux/dma-fence.h>
29 #include <linux/completion.h>
30 #include <linux/xarray.h>
32 #define MAX_WAIT_SCHED_ENTITY_Q_EMPTY msecs_to_jiffies(1000)
34 struct drm_gem_object;
36 struct drm_gpu_scheduler;
39 /* These are often used as an (initial) index
40 * to an array, and as such should start at 0.
42 enum drm_sched_priority {
43 DRM_SCHED_PRIORITY_MIN,
44 DRM_SCHED_PRIORITY_NORMAL,
45 DRM_SCHED_PRIORITY_HIGH,
46 DRM_SCHED_PRIORITY_KERNEL,
48 DRM_SCHED_PRIORITY_COUNT,
49 DRM_SCHED_PRIORITY_UNSET = -2
53 * struct drm_sched_entity - A wrapper around a job queue (typically
54 * attached to the DRM file_priv).
56 * Entities will emit jobs in order to their corresponding hardware
57 * ring, and the scheduler will alternate between entities based on
60 struct drm_sched_entity {
64 * Used to append this struct to the list of entities in the runqueue
65 * @rq under &drm_sched_rq.entities.
67 * Protected by &drm_sched_rq.lock of @rq.
69 struct list_head list;
74 * Runqueue on which this entity is currently scheduled.
76 * FIXME: Locking is very unclear for this. Writers are protected by
77 * @rq_lock, but readers are generally lockless and seem to just race
78 * with not even a READ_ONCE.
80 struct drm_sched_rq *rq;
85 * A list of schedulers (struct drm_gpu_scheduler). Jobs from this entity can
86 * be scheduled on any scheduler on this list.
88 * This can be modified by calling drm_sched_entity_modify_sched().
89 * Locking is entirely up to the driver, see the above function for more
92 * This will be set to NULL if &num_sched_list equals 1 and @rq has been
95 * FIXME: This means priority changes through
96 * drm_sched_entity_set_priority() will be lost henceforth in this case.
98 struct drm_gpu_scheduler **sched_list;
103 * Number of drm_gpu_schedulers in the @sched_list.
105 unsigned int num_sched_list;
110 * Priority of the entity. This can be modified by calling
111 * drm_sched_entity_set_priority(). Protected by &rq_lock.
113 enum drm_sched_priority priority;
118 * Lock to modify the runqueue to which this entity belongs.
123 * @job_queue: the list of jobs of this entity.
125 struct spsc_queue job_queue;
130 * A linearly increasing seqno incremented with each new
131 * &drm_sched_fence which is part of the entity.
133 * FIXME: Callers of drm_sched_job_arm() need to ensure correct locking,
134 * this doesn't need to be atomic.
141 * A unique context for all the fences which belong to this entity. The
142 * &drm_sched_fence.scheduled uses the fence_context but
143 * &drm_sched_fence.finished uses fence_context + 1.
145 uint64_t fence_context;
150 * The dependency fence of the job which is on the top of the job queue.
152 struct dma_fence *dependency;
157 * Callback for the dependency fence above.
159 struct dma_fence_cb cb;
164 * Points to entities' guilty.
171 * Points to the finished fence of the last scheduled job. Only written
172 * by the scheduler thread, can be accessed locklessly from
173 * drm_sched_job_arm() iff the queue is empty.
175 struct dma_fence *last_scheduled;
178 * @last_user: last group leader pushing a job into the entity.
180 struct task_struct *last_user;
185 * Marks the enity as removed from rq and destined for
186 * termination. This is set by calling drm_sched_entity_flush() and by
194 * Signals when entity is not in use, used to sequence entity cleanup in
195 * drm_sched_entity_fini().
197 struct completion entity_idle;
201 * struct drm_sched_rq - queue of entities to be scheduled.
203 * @lock: to modify the entities list.
204 * @sched: the scheduler to which this rq belongs to.
205 * @entities: list of the entities to be scheduled.
206 * @current_entity: the entity which is to be scheduled.
208 * Run queue is a set of entities scheduling command submissions for
209 * one specific ring. It implements the scheduling policy that selects
210 * the next entity to emit commands from.
212 struct drm_sched_rq {
214 struct drm_gpu_scheduler *sched;
215 struct list_head entities;
216 struct drm_sched_entity *current_entity;
220 * struct drm_sched_fence - fences corresponding to the scheduling of a job.
222 struct drm_sched_fence {
224 * @scheduled: this fence is what will be signaled by the scheduler
225 * when the job is scheduled.
227 struct dma_fence scheduled;
230 * @finished: this fence is what will be signaled by the scheduler
231 * when the job is completed.
233 * When setting up an out fence for the job, you should use
234 * this, since it's available immediately upon
235 * drm_sched_job_init(), and the fence returned by the driver
236 * from run_job() won't be created until the dependencies have
239 struct dma_fence finished;
242 * @parent: the fence returned by &drm_sched_backend_ops.run_job
243 * when scheduling the job on hardware. We signal the
244 * &drm_sched_fence.finished fence once parent is signalled.
246 struct dma_fence *parent;
248 * @sched: the scheduler instance to which the job having this struct
251 struct drm_gpu_scheduler *sched;
253 * @lock: the lock used by the scheduled and the finished fences.
257 * @owner: job owner for debugging
262 struct drm_sched_fence *to_drm_sched_fence(struct dma_fence *f);
265 * struct drm_sched_job - A job to be run by an entity.
267 * @queue_node: used to append this struct to the queue of jobs in an entity.
268 * @list: a job participates in a "pending" and "done" lists.
269 * @sched: the scheduler instance on which this job is scheduled.
270 * @s_fence: contains the fences for the scheduling of job.
271 * @finish_cb: the callback for the finished fence.
272 * @id: a unique id assigned to each job scheduled on the scheduler.
273 * @karma: increment on every hang caused by this job. If this exceeds the hang
274 * limit of the scheduler then the job is marked guilty and will not
275 * be scheduled further.
276 * @s_priority: the priority of the job.
277 * @entity: the entity to which this job belongs.
278 * @cb: the callback for the parent fence in s_fence.
280 * A job is created by the driver using drm_sched_job_init(), and
281 * should call drm_sched_entity_push_job() once it wants the scheduler
282 * to schedule the job.
284 struct drm_sched_job {
285 struct spsc_node queue_node;
286 struct list_head list;
287 struct drm_gpu_scheduler *sched;
288 struct drm_sched_fence *s_fence;
289 struct dma_fence_cb finish_cb;
292 enum drm_sched_priority s_priority;
293 struct drm_sched_entity *entity;
294 struct dma_fence_cb cb;
298 * Contains the dependencies as struct dma_fence for this job, see
299 * drm_sched_job_add_dependency() and
300 * drm_sched_job_add_implicit_dependencies().
302 struct xarray dependencies;
304 /** @last_dependency: tracks @dependencies as they signal */
305 unsigned long last_dependency;
308 static inline bool drm_sched_invalidate_job(struct drm_sched_job *s_job,
311 return s_job && atomic_inc_return(&s_job->karma) > threshold;
314 enum drm_gpu_sched_stat {
315 DRM_GPU_SCHED_STAT_NONE, /* Reserve 0 */
316 DRM_GPU_SCHED_STAT_NOMINAL,
317 DRM_GPU_SCHED_STAT_ENODEV,
321 * struct drm_sched_backend_ops
323 * Define the backend operations called by the scheduler,
324 * these functions should be implemented in driver side.
326 struct drm_sched_backend_ops {
330 * Called when the scheduler is considering scheduling this job next, to
331 * get another struct dma_fence for this job to block on. Once it
332 * returns NULL, run_job() may be called.
334 * If a driver exclusively uses drm_sched_job_add_dependency() and
335 * drm_sched_job_add_implicit_dependencies() this can be ommitted and
338 struct dma_fence *(*dependency)(struct drm_sched_job *sched_job,
339 struct drm_sched_entity *s_entity);
342 * @run_job: Called to execute the job once all of the dependencies
343 * have been resolved. This may be called multiple times, if
344 * timedout_job() has happened and drm_sched_job_recovery()
345 * decides to try it again.
347 struct dma_fence *(*run_job)(struct drm_sched_job *sched_job);
350 * @timedout_job: Called when a job has taken too long to execute,
351 * to trigger GPU recovery.
353 * This method is called in a workqueue context.
355 * Drivers typically issue a reset to recover from GPU hangs, and this
356 * procedure usually follows the following workflow:
358 * 1. Stop the scheduler using drm_sched_stop(). This will park the
359 * scheduler thread and cancel the timeout work, guaranteeing that
360 * nothing is queued while we reset the hardware queue
361 * 2. Try to gracefully stop non-faulty jobs (optional)
362 * 3. Issue a GPU reset (driver-specific)
363 * 4. Re-submit jobs using drm_sched_resubmit_jobs()
364 * 5. Restart the scheduler using drm_sched_start(). At that point, new
365 * jobs can be queued, and the scheduler thread is unblocked
367 * Note that some GPUs have distinct hardware queues but need to reset
368 * the GPU globally, which requires extra synchronization between the
369 * timeout handler of the different &drm_gpu_scheduler. One way to
370 * achieve this synchronization is to create an ordered workqueue
371 * (using alloc_ordered_workqueue()) at the driver level, and pass this
372 * queue to drm_sched_init(), to guarantee that timeout handlers are
373 * executed sequentially. The above workflow needs to be slightly
374 * adjusted in that case:
376 * 1. Stop all schedulers impacted by the reset using drm_sched_stop()
377 * 2. Try to gracefully stop non-faulty jobs on all queues impacted by
378 * the reset (optional)
379 * 3. Issue a GPU reset on all faulty queues (driver-specific)
380 * 4. Re-submit jobs on all schedulers impacted by the reset using
381 * drm_sched_resubmit_jobs()
382 * 5. Restart all schedulers that were stopped in step #1 using
385 * Return DRM_GPU_SCHED_STAT_NOMINAL, when all is normal,
386 * and the underlying driver has started or completed recovery.
388 * Return DRM_GPU_SCHED_STAT_ENODEV, if the device is no longer
389 * available, i.e. has been unplugged.
391 enum drm_gpu_sched_stat (*timedout_job)(struct drm_sched_job *sched_job);
394 * @free_job: Called once the job's finished fence has been signaled
395 * and it's time to clean it up.
397 void (*free_job)(struct drm_sched_job *sched_job);
401 * struct drm_gpu_scheduler
403 * @ops: backend operations provided by the driver.
404 * @hw_submission_limit: the max size of the hardware queue.
405 * @timeout: the time after which a job is removed from the scheduler.
406 * @name: name of the ring for which this scheduler is being used.
407 * @sched_rq: priority wise array of run queues.
408 * @wake_up_worker: the wait queue on which the scheduler sleeps until a job
409 * is ready to be scheduled.
410 * @job_scheduled: once @drm_sched_entity_do_release is called the scheduler
411 * waits on this wait queue until all the scheduled jobs are
413 * @hw_rq_count: the number of jobs currently in the hardware queue.
414 * @job_id_count: used to assign unique id to the each job.
415 * @timeout_wq: workqueue used to queue @work_tdr
416 * @work_tdr: schedules a delayed call to @drm_sched_job_timedout after the
417 * timeout interval is over.
418 * @thread: the kthread on which the scheduler which run.
419 * @pending_list: the list of jobs which are currently in the job queue.
420 * @job_list_lock: lock to protect the pending_list.
421 * @hang_limit: once the hangs by a job crosses this limit then it is marked
422 * guilty and it will no longer be considered for scheduling.
423 * @score: score to help loadbalancer pick a idle sched
424 * @_score: score used when the driver doesn't provide one
425 * @ready: marks if the underlying HW is ready to work
426 * @free_guilty: A hit to time out handler to free the guilty job.
428 * One scheduler is implemented for each hardware ring.
430 struct drm_gpu_scheduler {
431 const struct drm_sched_backend_ops *ops;
432 uint32_t hw_submission_limit;
435 struct drm_sched_rq sched_rq[DRM_SCHED_PRIORITY_COUNT];
436 wait_queue_head_t wake_up_worker;
437 wait_queue_head_t job_scheduled;
438 atomic_t hw_rq_count;
439 atomic64_t job_id_count;
440 struct workqueue_struct *timeout_wq;
441 struct delayed_work work_tdr;
442 struct task_struct *thread;
443 struct list_head pending_list;
444 spinlock_t job_list_lock;
452 int drm_sched_init(struct drm_gpu_scheduler *sched,
453 const struct drm_sched_backend_ops *ops,
454 uint32_t hw_submission, unsigned hang_limit,
455 long timeout, struct workqueue_struct *timeout_wq,
456 atomic_t *score, const char *name);
458 void drm_sched_fini(struct drm_gpu_scheduler *sched);
459 int drm_sched_job_init(struct drm_sched_job *job,
460 struct drm_sched_entity *entity,
462 void drm_sched_job_arm(struct drm_sched_job *job);
463 int drm_sched_job_add_dependency(struct drm_sched_job *job,
464 struct dma_fence *fence);
465 int drm_sched_job_add_implicit_dependencies(struct drm_sched_job *job,
466 struct drm_gem_object *obj,
470 void drm_sched_entity_modify_sched(struct drm_sched_entity *entity,
471 struct drm_gpu_scheduler **sched_list,
472 unsigned int num_sched_list);
474 void drm_sched_job_cleanup(struct drm_sched_job *job);
475 void drm_sched_wakeup(struct drm_gpu_scheduler *sched);
476 void drm_sched_stop(struct drm_gpu_scheduler *sched, struct drm_sched_job *bad);
477 void drm_sched_start(struct drm_gpu_scheduler *sched, bool full_recovery);
478 void drm_sched_resubmit_jobs(struct drm_gpu_scheduler *sched);
479 void drm_sched_resubmit_jobs_ext(struct drm_gpu_scheduler *sched, int max);
480 void drm_sched_increase_karma(struct drm_sched_job *bad);
481 void drm_sched_reset_karma(struct drm_sched_job *bad);
482 void drm_sched_increase_karma_ext(struct drm_sched_job *bad, int type);
483 bool drm_sched_dependency_optimized(struct dma_fence* fence,
484 struct drm_sched_entity *entity);
485 void drm_sched_fault(struct drm_gpu_scheduler *sched);
486 void drm_sched_job_kickout(struct drm_sched_job *s_job);
488 void drm_sched_rq_add_entity(struct drm_sched_rq *rq,
489 struct drm_sched_entity *entity);
490 void drm_sched_rq_remove_entity(struct drm_sched_rq *rq,
491 struct drm_sched_entity *entity);
493 int drm_sched_entity_init(struct drm_sched_entity *entity,
494 enum drm_sched_priority priority,
495 struct drm_gpu_scheduler **sched_list,
496 unsigned int num_sched_list,
498 long drm_sched_entity_flush(struct drm_sched_entity *entity, long timeout);
499 void drm_sched_entity_fini(struct drm_sched_entity *entity);
500 void drm_sched_entity_destroy(struct drm_sched_entity *entity);
501 void drm_sched_entity_select_rq(struct drm_sched_entity *entity);
502 struct drm_sched_job *drm_sched_entity_pop_job(struct drm_sched_entity *entity);
503 void drm_sched_entity_push_job(struct drm_sched_job *sched_job);
504 void drm_sched_entity_set_priority(struct drm_sched_entity *entity,
505 enum drm_sched_priority priority);
506 bool drm_sched_entity_is_ready(struct drm_sched_entity *entity);
508 struct drm_sched_fence *drm_sched_fence_alloc(
509 struct drm_sched_entity *s_entity, void *owner);
510 void drm_sched_fence_init(struct drm_sched_fence *fence,
511 struct drm_sched_entity *entity);
512 void drm_sched_fence_free(struct drm_sched_fence *fence);
514 void drm_sched_fence_scheduled(struct drm_sched_fence *fence);
515 void drm_sched_fence_finished(struct drm_sched_fence *fence);
517 unsigned long drm_sched_suspend_timeout(struct drm_gpu_scheduler *sched);
518 void drm_sched_resume_timeout(struct drm_gpu_scheduler *sched,
519 unsigned long remaining);
520 struct drm_gpu_scheduler *
521 drm_sched_pick_best(struct drm_gpu_scheduler **sched_list,
522 unsigned int num_sched_list);