Re: [PATCH] drm/sched: Extend the documentation.

Am 05.04.2018 um 00:32 schrieb Eric Anholt:

These comments answer all the questions I had for myself when implementing a driver using the GPU scheduler.

Signed-off-by: Eric Anholt eric@anholt.net

Reviewed-by: Christian König christian.koenig@amd.com

Already pushed to amd-staging-drm-next as well.

Thanks, Christian.

---

include/drm/gpu_scheduler.h | 46 +++++++++++++++++++++++++++++++++---- 1 file changed, 42 insertions(+), 4 deletions(-)

diff --git a/include/drm/gpu_scheduler.h b/include/drm/gpu_scheduler.h index dfd54fb94e10..c053a32341bf 100644 --- a/include/drm/gpu_scheduler.h +++ b/include/drm/gpu_scheduler.h @@ -43,10 +43,12 @@ enum drm_sched_priority { };

/**

• • A scheduler entity is a wrapper around a job queue or a group
• • of other entities. Entities take turns emitting jobs from their
• • job queues to corresponding hardware ring based on scheduling
• • policy.

• • drm_sched_entity - A wrapper around a job queue (typically attached
• • to the DRM file_priv).
• • 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;

@@ -78,7 +80,18 @@ struct drm_sched_rq {

struct drm_sched_fence { 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.
  

• */
  

  struct dma_fence finished;
• struct dma_fence_cb cb; struct dma_fence *parent; struct drm_gpu_scheduler *sched;

@@ -88,6 +101,13 @@ struct drm_sched_fence {

struct drm_sched_fence *to_drm_sched_fence(struct dma_fence *f);

+/**

• • drm_sched_job - A job to be run by an entity.
• • 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
• • to schedule the job.
• */ struct drm_sched_job { struct spsc_node queue_node; struct drm_gpu_scheduler *sched;

@@ -112,10 +132,28 @@ static inline bool drm_sched_invalidate_job(struct drm_sched_job *s_job,

• 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
  

• * 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
  

• * 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.
  

• */
  

  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.
  

• */
  

  void (*free_job)(struct drm_sched_job *sched_job); };