[PATCH 2/3] drm/scheduler: add documentation

Nayan Deshmukh nayan26deshmukh at gmail.com
Mon May 28 07:09:09 UTC 2018


If there are no more objections/suggestions I will send the patch with
the changes suggested by Alex and Christian later today.

Nayan

On Fri, May 25, 2018 at 8:24 PM, Alex Deucher <alexdeucher at gmail.com> wrote:
> On Fri, May 25, 2018 at 12:45 AM, Nayan Deshmukh
> <nayan26deshmukh at gmail.com> wrote:
>> convert existing raw comments into kernel-doc format as well
>> as add new documentation
>>
>> Signed-off-by: Alex Deucher <alexander.deucher at amd.com>
>> Signed-off-by: Nayan Deshmukh <nayan26deshmukh at gmail.com>
>
> Looks good.  just a couple comments below to clarify the language.
> With those fixed:
> Reviewed-by: Alex Deucher <alexander.deucher at amd.com>
>
>> ---
>>  drivers/gpu/drm/scheduler/gpu_scheduler.c | 214 ++++++++++++++++++++++++------
>>  include/drm/gpu_scheduler.h               | 153 +++++++++++++++++----
>>  2 files changed, 296 insertions(+), 71 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/scheduler/gpu_scheduler.c b/drivers/gpu/drm/scheduler/gpu_scheduler.c
>> index 44d480768dfe..c70c983e3e74 100644
>> --- a/drivers/gpu/drm/scheduler/gpu_scheduler.c
>> +++ b/drivers/gpu/drm/scheduler/gpu_scheduler.c
>> @@ -21,6 +21,29 @@
>>   *
>>   */
>>
>> +/**
>> + * DOC: Overview
>> + *
>> + * The GPU scheduler provides entities which allow userspace to push jobs
>> + * into software queues which are then scheduled on a hardware run queue.
>> + * The software queues have a priority among them. The scheduler selects the entities
>> + * from the run queue using FIFO. The scheduler provides dependency handling
>
> a FIFO
>
>> + * features among jobs. The driver is supposed to provide functions for backend
>
> The driver provides callback functions for backend
>
>> + * operations to the scheduler like submitting a job to hardware run queue,
>> + * returning the dependency of a job etc.
>> + *
>> + * The organisation of the scheduler is the following:-
>
> drop the -
>
>> + *
>> + * 1. Each ring buffer has one scheduler
>
> Each hw run queue
>
>> + * 2. Each scheduler has multiple run queues with different priorities
>> + *    (i.e. HIGH_HW,HIGH_SW, KERNEL, NORMAL)
>
> s/i.e./e.g.,/
>
>> + * 3. Each run queue has a queue of entities to schedule
>
> Each scheduler run queue has a queue of entities to schedule
>
>> + * 4. Entities themselves maintain a queue of jobs that will be scheduled on
>> + *    the hardware.
>> + *
>> + * The jobs in a entity are always scheduled in the order that they were pushed.
>> + */
>> +
>>  #include <linux/kthread.h>
>>  #include <linux/wait.h>
>>  #include <linux/sched.h>
>> @@ -39,7 +62,13 @@ static bool drm_sched_entity_is_ready(struct drm_sched_entity *entity);
>>  static void drm_sched_wakeup(struct drm_gpu_scheduler *sched);
>>  static void drm_sched_process_job(struct dma_fence *f, struct dma_fence_cb *cb);
>>
>> -/* Initialize a given run queue struct */
>> +/**
>> + * drm_sched_rq_init - initialize a given run queue struct
>> + *
>> + * @rq: scheduler run queue
>> + *
>> + * Initializes a scheduler runqueue.
>> + */
>>  static void drm_sched_rq_init(struct drm_sched_rq *rq)
>>  {
>>         spin_lock_init(&rq->lock);
>> @@ -47,6 +76,14 @@ static void drm_sched_rq_init(struct drm_sched_rq *rq)
>>         rq->current_entity = NULL;
>>  }
>>
>> +/**
>> + * drm_sched_rq_add_entity - add an entity
>> + *
>> + * @rq: scheduler run queue
>> + * @entity: scheduler entity
>> + *
>> + * Adds a scheduler entity to the run queue.
>> + */
>>  static void drm_sched_rq_add_entity(struct drm_sched_rq *rq,
>>                                     struct drm_sched_entity *entity)
>>  {
>> @@ -57,6 +94,14 @@ static void drm_sched_rq_add_entity(struct drm_sched_rq *rq,
>>         spin_unlock(&rq->lock);
>>  }
>>
>> +/**
>> + * drm_sched_rq_remove_entity - remove an entity
>> + *
>> + * @rq: scheduler run queue
>> + * @entity: scheduler entity
>> + *
>> + * Removes a scheduler entity from the run queue.
>> + */
>>  static void drm_sched_rq_remove_entity(struct drm_sched_rq *rq,
>>                                        struct drm_sched_entity *entity)
>>  {
>> @@ -70,9 +115,9 @@ static void drm_sched_rq_remove_entity(struct drm_sched_rq *rq,
>>  }
>>
>>  /**
>> - * Select an entity which could provide a job to run
>> + * drm_sched_rq_select_entity - Select an entity which could provide a job to run
>>   *
>> - * @rq         The run queue to check.
>> + * @rq: scheduler run queue to check.
>>   *
>>   * Try to find a ready entity, returns NULL if none found.
>>   */
>> @@ -112,15 +157,16 @@ drm_sched_rq_select_entity(struct drm_sched_rq *rq)
>>  }
>>
>>  /**
>> - * Init a context entity used by scheduler when submit to HW ring.
>> + * drm_sched_entity_init - Init a context entity used by scheduler when
>> + * submit to HW ring.
>>   *
>> - * @sched      The pointer to the scheduler
>> - * @entity     The pointer to a valid drm_sched_entity
>> - * @rq         The run queue this entity belongs
>> - * @guilty      atomic_t set to 1 when a job on this queue
>> - *              is found to be guilty causing a timeout
>> + * @sched: scheduler instance
>> + * @entity: scheduler entity to init
>> + * @rq: the run queue this entity belongs
>> + * @guilty: atomic_t set to 1 when a job on this queue
>> + *          is found to be guilty causing a timeout
>>   *
>> - * return 0 if succeed. negative error code on failure
>> + * Returns 0 on success or a negative error code on failure.
>>  */
>>  int drm_sched_entity_init(struct drm_gpu_scheduler *sched,
>>                           struct drm_sched_entity *entity,
>> @@ -149,10 +195,10 @@ int drm_sched_entity_init(struct drm_gpu_scheduler *sched,
>>  EXPORT_SYMBOL(drm_sched_entity_init);
>>
>>  /**
>> - * Query if entity is initialized
>> + * drm_sched_entity_is_initialized - Query if entity is initialized
>>   *
>> - * @sched       Pointer to scheduler instance
>> - * @entity     The pointer to a valid scheduler entity
>> + * @sched: Pointer to scheduler instance
>> + * @entity: The pointer to a valid scheduler entity
>>   *
>>   * return true if entity is initialized, false otherwise
>>  */
>> @@ -164,11 +210,11 @@ static bool drm_sched_entity_is_initialized(struct drm_gpu_scheduler *sched,
>>  }
>>
>>  /**
>> - * Check if entity is idle
>> + * drm_sched_entity_is_idle - Check if entity is idle
>>   *
>> - * @entity     The pointer to a valid scheduler entity
>> + * @entity: scheduler entity
>>   *
>> - * Return true if entity don't has any unscheduled jobs.
>> + * Returns true if the entity does not have any unscheduled jobs.
>>   */
>>  static bool drm_sched_entity_is_idle(struct drm_sched_entity *entity)
>>  {
>> @@ -180,9 +226,9 @@ static bool drm_sched_entity_is_idle(struct drm_sched_entity *entity)
>>  }
>>
>>  /**
>> - * Check if entity is ready
>> + * drm_sched_entity_is_ready - Check if entity is ready
>>   *
>> - * @entity     The pointer to a valid scheduler entity
>> + * @entity: scheduler entity
>>   *
>>   * Return true if entity could provide a job.
>>   */
>> @@ -210,12 +256,12 @@ static void drm_sched_entity_kill_jobs_cb(struct dma_fence *f,
>>
>>
>>  /**
>> - * Destroy a context entity
>> + * drm_sched_entity_do_release - Destroy a context entity
>>   *
>> - * @sched       Pointer to scheduler instance
>> - * @entity     The pointer to a valid scheduler entity
>> + * @sched: scheduler instance
>> + * @entity: scheduler entity
>>   *
>> - * Splitting drm_sched_entity_fini() into two functions, The first one is does the waiting,
>> + * Splitting drm_sched_entity_fini() into two functions, The first one does the waiting,
>>   * removes the entity from the runqueue and returns an error when the process was killed.
>>   */
>>  void drm_sched_entity_do_release(struct drm_gpu_scheduler *sched,
>> @@ -237,12 +283,13 @@ void drm_sched_entity_do_release(struct drm_gpu_scheduler *sched,
>>  EXPORT_SYMBOL(drm_sched_entity_do_release);
>>
>>  /**
>> - * Destroy a context entity
>> + * drm_sched_entity_cleanup - Destroy a context entity
>>   *
>> - * @sched       Pointer to scheduler instance
>> - * @entity     The pointer to a valid scheduler entity
>> + * @sched: scheduler instance
>> + * @entity: scheduler entity
>>   *
>> - * The second one then goes over the entity and signals all jobs with an error code.
>> + * This should be called after @drm_sched_entity_do_release. It goes over the
>> + * entity and signals all jobs with an error code if the process was killed.
>>   */
>>  void drm_sched_entity_cleanup(struct drm_gpu_scheduler *sched,
>>                            struct drm_sched_entity *entity)
>> @@ -281,6 +328,14 @@ void drm_sched_entity_cleanup(struct drm_gpu_scheduler *sched,
>>  }
>>  EXPORT_SYMBOL(drm_sched_entity_cleanup);
>>
>> +/**
>> + * drm_sched_entity_fini - Destroy a context entity
>> + *
>> + * @sched: scheduler instance
>> + * @entity: scheduler entity
>> + *
>> + * Calls drm_sched_entity_do_release() and drm_sched_entity_cleanup()
>> + */
>>  void drm_sched_entity_fini(struct drm_gpu_scheduler *sched,
>>                                 struct drm_sched_entity *entity)
>>  {
>> @@ -306,6 +361,15 @@ static void drm_sched_entity_clear_dep(struct dma_fence *f, struct dma_fence_cb
>>         dma_fence_put(f);
>>  }
>>
>> +/**
>> + * drm_sched_entity_set_rq - Sets the run queue for an entity
>> + *
>> + * @entity: scheduler entity
>> + * @rq: scheduler run queue
>> + *
>> + * Sets the run queue for an entity and removes the entity from the previous
>> + * run queue in which was present.
>> + */
>>  void drm_sched_entity_set_rq(struct drm_sched_entity *entity,
>>                              struct drm_sched_rq *rq)
>>  {
>> @@ -325,6 +389,14 @@ void drm_sched_entity_set_rq(struct drm_sched_entity *entity,
>>  }
>>  EXPORT_SYMBOL(drm_sched_entity_set_rq);
>>
>> +/**
>> + * drm_sched_dependency_optimized
>> + *
>> + * @fence: the dependency fence
>> + * @entity: the entity which depends on the above fence
>> + *
>> + * Returns true if the dependency can be optimized and false otherwise
>> + */
>>  bool drm_sched_dependency_optimized(struct dma_fence* fence,
>>                                     struct drm_sched_entity *entity)
>>  {
>> @@ -413,9 +485,10 @@ drm_sched_entity_pop_job(struct drm_sched_entity *entity)
>>  }
>>
>>  /**
>> - * Submit a job to the job queue
>> + * drm_sched_entity_push_job - Submit a job to the entity's job queue
>>   *
>> - * @sched_job          The pointer to job required to submit
>> + * @sched_job: job to submit
>> + * @entity: scheduler entity
>>   *
>>   * Note: To guarantee that the order of insertion to queue matches
>>   * the job's fence sequence number this function should be
>> @@ -506,6 +579,13 @@ static void drm_sched_job_timedout(struct work_struct *work)
>>         job->sched->ops->timedout_job(job);
>>  }
>>
>> +/**
>> + * drm_sched_hw_job_reset - stop the scheduler if it contains the bad job
>> + *
>> + * @sched: scheduler instance
>> + * @bad: bad scheduler job
>> + *
>> + */
>>  void drm_sched_hw_job_reset(struct drm_gpu_scheduler *sched, struct drm_sched_job *bad)
>>  {
>>         struct drm_sched_job *s_job;
>> @@ -550,6 +630,12 @@ void drm_sched_hw_job_reset(struct drm_gpu_scheduler *sched, struct drm_sched_jo
>>  }
>>  EXPORT_SYMBOL(drm_sched_hw_job_reset);
>>
>> +/**
>> + * drm_sched_job_recovery - recover jobs after a reset
>> + *
>> + * @sched: scheduler instance
>> + *
>> + */
>>  void drm_sched_job_recovery(struct drm_gpu_scheduler *sched)
>>  {
>>         struct drm_sched_job *s_job, *tmp;
>> @@ -599,10 +685,17 @@ void drm_sched_job_recovery(struct drm_gpu_scheduler *sched)
>>  EXPORT_SYMBOL(drm_sched_job_recovery);
>>
>>  /**
>> - * Init a sched_job with basic field
>> + * drm_sched_job_init - init a scheduler job
>>   *
>> - * Note: Refer to drm_sched_entity_push_job documentation
>> + * @job: scheduler job to init
>> + * @sched: scheduler instance
>> + * @entity: scheduler entity to use
>> + * @owner: job owner for debugging
>> + *
>> + * Refer to drm_sched_entity_push_job() documentation
>>   * for locking considerations.
>> + *
>> + * Returns 0 for success, negative error code otherwise.
>>   */
>>  int drm_sched_job_init(struct drm_sched_job *job,
>>                        struct drm_gpu_scheduler *sched,
>> @@ -626,7 +719,11 @@ int drm_sched_job_init(struct drm_sched_job *job,
>>  EXPORT_SYMBOL(drm_sched_job_init);
>>
>>  /**
>> - * Return ture if we can push more jobs to the hw.
>> + * drm_sched_ready - is the scheduler ready
>> + *
>> + * @sched: scheduler instance
>> + *
>> + * Return true if we can push more jobs to the hw, otherwise false.
>>   */
>>  static bool drm_sched_ready(struct drm_gpu_scheduler *sched)
>>  {
>> @@ -635,7 +732,10 @@ static bool drm_sched_ready(struct drm_gpu_scheduler *sched)
>>  }
>>
>>  /**
>> - * Wake up the scheduler when it is ready
>> + * drm_sched_wakeup - Wake up the scheduler when it is ready
>> + *
>> + * @sched: scheduler instance
>> + *
>>   */
>>  static void drm_sched_wakeup(struct drm_gpu_scheduler *sched)
>>  {
>> @@ -644,8 +744,12 @@ static void drm_sched_wakeup(struct drm_gpu_scheduler *sched)
>>  }
>>
>>  /**
>> - * Select next entity to process
>> -*/
>> + * drm_sched_select_entity - Select next entity to process
>> + *
>> + * @sched: scheduler instance
>> + *
>> + * Returns the entity to process or NULL if none are found.
>> + */
>>  static struct drm_sched_entity *
>>  drm_sched_select_entity(struct drm_gpu_scheduler *sched)
>>  {
>> @@ -665,6 +769,14 @@ drm_sched_select_entity(struct drm_gpu_scheduler *sched)
>>         return entity;
>>  }
>>
>> +/**
>> + * drm_sched_process_job - process a job
>> + *
>> + * @f: fence
>> + * @cb: fence callbacks
>> + *
>> + * Called after job has finished execution.
>> + */
>>  static void drm_sched_process_job(struct dma_fence *f, struct dma_fence_cb *cb)
>>  {
>>         struct drm_sched_fence *s_fence =
>> @@ -680,6 +792,13 @@ static void drm_sched_process_job(struct dma_fence *f, struct dma_fence_cb *cb)
>>         wake_up_interruptible(&sched->wake_up_worker);
>>  }
>>
>> +/**
>> + * drm_sched_blocked - check if the scheduler is blocked
>> + *
>> + * @sched: scheduler instance
>> + *
>> + * Returns true if blocked, otherwise false.
>> + */
>>  static bool drm_sched_blocked(struct drm_gpu_scheduler *sched)
>>  {
>>         if (kthread_should_park()) {
>> @@ -690,6 +809,13 @@ static bool drm_sched_blocked(struct drm_gpu_scheduler *sched)
>>         return false;
>>  }
>>
>> +/**
>> + * drm_sched_main - main scheduler thread
>> + *
>> + * @param: scheduler instance
>> + *
>> + * Returns 0.
>> + */
>>  static int drm_sched_main(void *param)
>>  {
>>         struct sched_param sparam = {.sched_priority = 1};
>> @@ -744,15 +870,17 @@ static int drm_sched_main(void *param)
>>  }
>>
>>  /**
>> - * Init a gpu scheduler instance
>> + * drm_sched_init - Init a gpu scheduler instance
>>   *
>> - * @sched              The pointer to the scheduler
>> - * @ops                        The backend operations for this scheduler.
>> - * @hw_submissions     Number of hw submissions to do.
>> - * @name               Name used for debugging
>> + * @sched: scheduler instance
>> + * @ops: backend operations for this scheduler
>> + * @hw_submission: number of hw submissions that can be in flight
>> + * @hang_limit: number of times to allow a job to hang before dropping it
>> + * @timeout: timeout value in jiffies for the scheduler
>> + * @name: name used for debugging
>>   *
>>   * Return 0 on success, otherwise error code.
>> -*/
>> + */
>>  int drm_sched_init(struct drm_gpu_scheduler *sched,
>>                    const struct drm_sched_backend_ops *ops,
>>                    unsigned hw_submission,
>> @@ -788,9 +916,11 @@ int drm_sched_init(struct drm_gpu_scheduler *sched,
>>  EXPORT_SYMBOL(drm_sched_init);
>>
>>  /**
>> - * Destroy a gpu scheduler
>> + * drm_sched_fini - Destroy a gpu scheduler
>> + *
>> + * @sched: scheduler instance
>>   *
>> - * @sched      The pointer to the scheduler
>> + * Tears down and cleans up the scheduler.
>>   */
>>  void drm_sched_fini(struct drm_gpu_scheduler *sched)
>>  {
>> diff --git a/include/drm/gpu_scheduler.h b/include/drm/gpu_scheduler.h
>> index dec655894d08..496442f12bff 100644
>> --- a/include/drm/gpu_scheduler.h
>> +++ b/include/drm/gpu_scheduler.h
>> @@ -43,13 +43,33 @@ enum drm_sched_priority {
>>  };
>>
>>  /**
>> - * drm_sched_entity - A wrapper around a job queue (typically attached
>> - * to the DRM file_priv).
>> + * struct drm_sched_entity - A wrapper around a job queue (typically
>> + * attached to the DRM file_priv).
>> + *
>> + * @list: used to append this struct to the list of entities in the
>> + *        runqueue.
>> + * @rq: runqueue to which this entity belongs.
>> + * @rq_lock: lock to modify the runqueue to which this entity belongs.
>> + * @sched: the scheduler instance to which this entity is enqueued.
>> + * @job_queue: the list of jobs of this entity.
>> + * @fence_seq: a linearly increasing seqno incremented with each
>> + *             new &drm_sched_fence which is part of the entity.
>> + * @fence_context: a unique context for all the fences which belong
>> + *                 to this entity.
>> + *                 The &drm_sched_fence.scheduled uses the
>> + *                 fence_context but &drm_sched_fence.finished uses
>> + *                 fence_context + 1.
>> + * @dependency: the dependency fence of the job which is on the top
>> + *              of the job queue.
>> + * @cb: callback for the dependency fence above.
>> + * @guilty: points to ctx's guilty.
>> + * @fini_status: contains the exit status in case the process was signalled.
>> + * @last_scheduled: points to the finished fence of the last scheduled job.
>>   *
>>   * Entities will emit jobs in order to their corresponding hardware
>>   * ring, and the scheduler will alternate between entities based on
>>   * scheduling policy.
>> -*/
>> + */
>>  struct drm_sched_entity {
>>         struct list_head                list;
>>         struct drm_sched_rq             *rq;
>> @@ -63,47 +83,96 @@ struct drm_sched_entity {
>>
>>         struct dma_fence                *dependency;
>>         struct dma_fence_cb             cb;
>> -       atomic_t                        *guilty; /* points to ctx's guilty */
>> -       int            fini_status;
>> -       struct dma_fence    *last_scheduled;
>> +       atomic_t                        *guilty;
>> +       int                             fini_status;
>> +       struct dma_fence                *last_scheduled;
>>  };
>>
>>  /**
>> + * struct drm_sched_rq - queue of entities to be scheduled.
>> + *
>> + * @lock: to modify the entities list.
>> + * @entities: list of the entities to be scheduled.
>> + * @current_entity: the entity which is to be scheduled.
>> + *
>>   * Run queue is a set of entities scheduling command submissions for
>>   * one specific ring. It implements the scheduling policy that selects
>>   * the next entity to emit commands from.
>> -*/
>> + */
>>  struct drm_sched_rq {
>>         spinlock_t                      lock;
>>         struct list_head                entities;
>>         struct drm_sched_entity         *current_entity;
>>  };
>>
>> +/**
>> + * struct drm_sched_fence - fences corresponding to the scheduling of a job.
>> + */
>>  struct drm_sched_fence {
>> +        /**
>> +         * @scheduled: this fence is what will be signaled by the scheduler
>> +         * when the job is scheduled.
>> +         */
>>         struct dma_fence                scheduled;
>>
>> -       /* This fence is what will be signaled by the scheduler when
>> -        * the job is completed.
>> -        *
>> -        * When setting up an out fence for the job, you should use
>> -        * this, since it's available immediately upon
>> -        * drm_sched_job_init(), and the fence returned by the driver
>> -        * from run_job() won't be created until the dependencies have
>> -        * resolved.
>> -        */
>> +        /**
>> +         * @finished: this fence is what will be signaled by the scheduler
>> +         * when the job is completed.
>> +         *
>> +         * When setting up an out fence for the job, you should use
>> +         * this, since it's available immediately upon
>> +         * drm_sched_job_init(), and the fence returned by the driver
>> +         * from run_job() won't be created until the dependencies have
>> +         * resolved.
>> +         */
>>         struct dma_fence                finished;
>>
>> +        /**
>> +         * @cb: the callback for the parent fence below.
>> +         */
>>         struct dma_fence_cb             cb;
>> +        /**
>> +         * @parent: the fence returned by &drm_sched_backend_ops.run_job
>> +         * when scheduling the job on hardware. We signal the
>> +         * &drm_sched_fence.finished fence once parent is signalled.
>> +         */
>>         struct dma_fence                *parent;
>> +        /**
>> +         * @sched: the scheduler instance to which the job having this struct
>> +         * belongs to.
>> +         */
>>         struct drm_gpu_scheduler        *sched;
>> +        /**
>> +         * @lock: the lock used by the scheduled and the finished fences.
>> +         */
>>         spinlock_t                      lock;
>> +        /**
>> +         * @owner: job owner for debugging
>> +         */
>>         void                            *owner;
>>  };
>>
>>  struct drm_sched_fence *to_drm_sched_fence(struct dma_fence *f);
>>
>>  /**
>> - * drm_sched_job - A job to be run by an entity.
>> + * struct drm_sched_job - A job to be run by an entity.
>> + *
>> + * @queue_node: used to append this struct to the queue of jobs in an entity.
>> + * @sched: the scheduler instance on which this job is scheduled.
>> + * @s_fence: contains the fences for the scheduling of job.
>> + * @finish_cb: the callback for the finished fence.
>> + * @finish_work: schedules the function @drm_sched_job_finish once the job has
>> + *               finished to remove the job from the
>> + *               @drm_gpu_scheduler.ring_mirror_list.
>> + * @node: used to append this struct to the @drm_gpu_scheduler.ring_mirror_list.
>> + * @work_tdr: schedules a delayed call to @drm_sched_job_timedout after the timeout
>> + *            interval is over.
>> + * @id: a unique id assigned to each job scheduled on the scheduler.
>> + * @karma: increment on every hang caused by this job. If this exceeds the hang
>> + *         limit of the scheduler then the job is marked guilty and will not
>> + *         be scheduled further.
>> + * @s_priority: the priority of the job.
>> + * @entity: the entity to which this job belongs.
>>   *
>>   * A job is created by the driver using drm_sched_job_init(), and
>>   * should call drm_sched_entity_push_job() once it wants the scheduler
>> @@ -130,38 +199,64 @@ static inline bool drm_sched_invalidate_job(struct drm_sched_job *s_job,
>>  }
>>
>>  /**
>> + * struct drm_sched_backend_ops
>> + *
>>   * Define the backend operations called by the scheduler,
>> - * these functions should be implemented in driver side
>> -*/
>> + * these functions should be implemented in driver side.
>> + */
>>  struct drm_sched_backend_ops {
>> -       /* Called when the scheduler is considering scheduling this
>> -        * job next, to get another struct dma_fence for this job to
>> +       /**
>> +         * @dependency: Called when the scheduler is considering scheduling
>> +         * this job next, to get another struct dma_fence for this job to
>>          * block on.  Once it returns NULL, run_job() may be called.
>>          */
>>         struct dma_fence *(*dependency)(struct drm_sched_job *sched_job,
>>                                         struct drm_sched_entity *s_entity);
>>
>> -       /* Called to execute the job once all of the dependencies have
>> -        * been resolved.  This may be called multiple times, if
>> +       /**
>> +         * @run_job: Called to execute the job once all of the dependencies
>> +         * have been resolved.  This may be called multiple times, if
>>          * timedout_job() has happened and drm_sched_job_recovery()
>>          * decides to try it again.
>>          */
>>         struct dma_fence *(*run_job)(struct drm_sched_job *sched_job);
>>
>> -       /* Called when a job has taken too long to execute, to trigger
>> -        * GPU recovery.
>> +       /**
>> +         * @timedout_job: Called when a job has taken too long to execute,
>> +         * to trigger GPU recovery.
>>          */
>>         void (*timedout_job)(struct drm_sched_job *sched_job);
>>
>> -       /* Called once the job's finished fence has been signaled and
>> -        * it's time to clean it up.
>> +       /**
>> +         * @free_job: Called once the job's finished fence has been signaled
>> +         * and it's time to clean it up.
>>          */
>>         void (*free_job)(struct drm_sched_job *sched_job);
>>  };
>>
>>  /**
>> - * One scheduler is implemented for each hardware ring
>> -*/
>> + * struct drm_gpu_scheduler
>> + *
>> + * @ops: backend operations provided by the driver.
>> + * @hw_submission_limit: the max size of the hardware queue.
>> + * @timeout: the time after which a job is removed from the scheduler.
>> + * @name: name of the ring for which this scheduler is being used.
>> + * @sched_rq: priority wise array of run queues.
>> + * @wake_up_worker: the wait queue on which the scheduler sleeps until a job
>> + *                  is ready to be scheduled.
>> + * @job_scheduled: once @drm_sched_entity_do_release is called the scheduler
>> + *                 waits on this wait queue until all the scheduled jobs are
>> + *                 finished.
>> + * @hw_rq_count: the number of jobs currently in the hardware queue.
>> + * @job_id_count: used to assign unique id to the each job.
>> + * @thread: the kthread on which the scheduler which run.
>> + * @ring_mirror_list: the list of jobs which are currently in the job queue.
>> + * @job_list_lock: lock to protect the ring_mirror_list.
>> + * @hang_limit: once the hangs by a job crosses this limit then it is marked
>> + *              guilty and it will be considered for scheduling further.
>> + *
>> + * One scheduler is implemented for each hardware ring.
>> + */
>>  struct drm_gpu_scheduler {
>>         const struct drm_sched_backend_ops      *ops;
>>         uint32_t                        hw_submission_limit;
>> --
>> 2.14.3
>>


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