Re: [RFC PATCH 02/10] drm/sched: Move schedule policy to scheduler / entity

[Matthew Brost <matthew.brost@intel.com>]

On Wed, Apr 05, 2023 at 01:37:22PM -0400, Luben Tuikov wrote:
> Hi,
> 
> Inlined:
> 

Thanks for the feedback.

> On 2023-04-03 20:22, Matthew Brost wrote:
> > Rather than a global modparam for scheduling policy, move the scheduling
> > policy to scheduler / entity so user can control each scheduler / entity
> > policy.
> > 
> > Signed-off-by: Matthew Brost <matthew.brost@intel.com>
> > ---
> >  drivers/gpu/drm/amd/amdgpu/amdgpu_device.c |  1 +
> >  drivers/gpu/drm/etnaviv/etnaviv_sched.c    |  3 ++-
> >  drivers/gpu/drm/lima/lima_sched.c          |  3 ++-
> >  drivers/gpu/drm/msm/msm_ringbuffer.c       |  3 ++-
> >  drivers/gpu/drm/panfrost/panfrost_job.c    |  3 ++-
> >  drivers/gpu/drm/scheduler/sched_entity.c   | 25 ++++++++++++++++++----
> >  drivers/gpu/drm/scheduler/sched_main.c     | 21 +++++++++++++-----
> >  drivers/gpu/drm/v3d/v3d_sched.c            | 15 ++++++++-----
> >  include/drm/gpu_scheduler.h                | 23 ++++++++++++++------
> >  9 files changed, 73 insertions(+), 24 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> > index 00c9c03c8f94..4df0fca5a74c 100644
> > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> > @@ -2368,6 +2368,7 @@ static int amdgpu_device_init_schedulers(struct amdgpu_device *adev)
> >  				   ring->num_hw_submission, amdgpu_job_hang_limit,
> >  				   timeout, adev->reset_domain->wq,
> >  				   ring->sched_score, ring->name,
> > +				   DRM_SCHED_POLICY_DEFAULT,
> >  				   adev->dev);
> >  		if (r) {
> >  			DRM_ERROR("Failed to create scheduler on ring %s.\n",
> > diff --git a/drivers/gpu/drm/etnaviv/etnaviv_sched.c b/drivers/gpu/drm/etnaviv/etnaviv_sched.c
> > index 8486a2923f1b..61204a3f8b0b 100644
> > --- a/drivers/gpu/drm/etnaviv/etnaviv_sched.c
> > +++ b/drivers/gpu/drm/etnaviv/etnaviv_sched.c
> > @@ -136,7 +136,8 @@ int etnaviv_sched_init(struct etnaviv_gpu *gpu)
> >  	ret = drm_sched_init(&gpu->sched, &etnaviv_sched_ops, NULL,
> >  			     etnaviv_hw_jobs_limit, etnaviv_job_hang_limit,
> >  			     msecs_to_jiffies(500), NULL, NULL,
> > -			     dev_name(gpu->dev), gpu->dev);
> > +			     dev_name(gpu->dev), DRM_SCHED_POLICY_DEFAULT,
> > +			     gpu->dev);
> >  	if (ret)
> >  		return ret;
> >  
> > diff --git a/drivers/gpu/drm/lima/lima_sched.c b/drivers/gpu/drm/lima/lima_sched.c
> > index 54f53bece27c..33042ba6ae93 100644
> > --- a/drivers/gpu/drm/lima/lima_sched.c
> > +++ b/drivers/gpu/drm/lima/lima_sched.c
> > @@ -491,7 +491,8 @@ int lima_sched_pipe_init(struct lima_sched_pipe *pipe, const char *name)
> >  	return drm_sched_init(&pipe->base, &lima_sched_ops, NULL, 1,
> >  			      lima_job_hang_limit,
> >  			      msecs_to_jiffies(timeout), NULL,
> > -			      NULL, name, pipe->ldev->dev);
> > +			      NULL, name, DRM_SCHED_POLICY_DEFAULT,
> > +			      pipe->ldev->dev);
> >  }
> >  
> >  void lima_sched_pipe_fini(struct lima_sched_pipe *pipe)
> > diff --git a/drivers/gpu/drm/msm/msm_ringbuffer.c b/drivers/gpu/drm/msm/msm_ringbuffer.c
> > index 5879fc262047..f408a9097315 100644
> > --- a/drivers/gpu/drm/msm/msm_ringbuffer.c
> > +++ b/drivers/gpu/drm/msm/msm_ringbuffer.c
> > @@ -97,7 +97,8 @@ struct msm_ringbuffer *msm_ringbuffer_new(struct msm_gpu *gpu, int id,
> >  
> >  	ret = drm_sched_init(&ring->sched, &msm_sched_ops, NULL,
> >  			num_hw_submissions, 0, sched_timeout,
> > -			NULL, NULL, to_msm_bo(ring->bo)->name, gpu->dev->dev);
> > +			NULL, NULL, to_msm_bo(ring->bo)->name,
> > +			DRM_SCHED_POLICY_DEFAULT, gpu->dev->dev);
> >  	if (ret) {
> >  		goto fail;
> >  	}
> > diff --git a/drivers/gpu/drm/panfrost/panfrost_job.c b/drivers/gpu/drm/panfrost/panfrost_job.c
> > index f48b07056a16..effa48b33dce 100644
> > --- a/drivers/gpu/drm/panfrost/panfrost_job.c
> > +++ b/drivers/gpu/drm/panfrost/panfrost_job.c
> > @@ -819,7 +819,8 @@ int panfrost_job_init(struct panfrost_device *pfdev)
> >  				     nentries, 0,
> >  				     msecs_to_jiffies(JOB_TIMEOUT_MS),
> >  				     pfdev->reset.wq,
> > -				     NULL, "pan_js", pfdev->dev);
> > +				     NULL, "pan_js", DRM_SCHED_POLICY_DEFAULT,
> > +				     pfdev->dev);
> >  		if (ret) {
> >  			dev_err(pfdev->dev, "Failed to create scheduler: %d.", ret);
> >  			goto err_sched;
> > diff --git a/drivers/gpu/drm/scheduler/sched_entity.c b/drivers/gpu/drm/scheduler/sched_entity.c
> > index 15d04a0ec623..f1299e51860b 100644
> > --- a/drivers/gpu/drm/scheduler/sched_entity.c
> > +++ b/drivers/gpu/drm/scheduler/sched_entity.c
> > @@ -33,6 +33,20 @@
> >  #define to_drm_sched_job(sched_job)		\
> >  		container_of((sched_job), struct drm_sched_job, queue_node)
> >  
> > +static bool bad_policies(struct drm_gpu_scheduler **sched_list,
> > +			 unsigned int num_sched_list)
> > +{
> > +	enum drm_sched_policy sched_policy = sched_list[0]->sched_policy;
> > +	unsigned int i;
> > +
> > +	/* All scdedule policies must match */
> > +	for (i = 1; i < num_sched_list; ++i)
> > +		if (sched_policy != sched_list[i]->sched_policy)
> > +			return true;
> > +
> > +	return false;
> > +}
> > +
> >  /**
> >   * drm_sched_entity_init - Init a context entity used by scheduler when
> >   * submit to HW ring.
> > @@ -62,7 +76,8 @@ int drm_sched_entity_init(struct drm_sched_entity *entity,
> >  			  unsigned int num_sched_list,
> >  			  atomic_t *guilty)
> >  {
> > -	if (!(entity && sched_list && (num_sched_list == 0 || sched_list[0])))
> > +	if (!(entity && sched_list && (num_sched_list == 0 || sched_list[0])) ||
> > +	    bad_policies(sched_list, num_sched_list))
> >  		return -EINVAL;
> >  
> >  	memset(entity, 0, sizeof(struct drm_sched_entity));
> > @@ -75,8 +90,10 @@ int drm_sched_entity_init(struct drm_sched_entity *entity,
> >  	entity->last_scheduled = NULL;
> >  	RB_CLEAR_NODE(&entity->rb_tree_node);
> >  
> > -	if(num_sched_list)
> > +	if(num_sched_list) {
> >  		entity->rq = &sched_list[0]->sched_rq[entity->priority];
> > +		entity->sched_policy = sched_list[0]->sched_policy;
> > +	}
> >  
> >  	init_completion(&entity->entity_idle);
> >  
> > @@ -440,7 +457,7 @@ struct drm_sched_job *drm_sched_entity_pop_job(struct drm_sched_entity *entity)
> >  	 * Update the entity's location in the min heap according to
> >  	 * the timestamp of the next job, if any.
> >  	 */
> > -	if (drm_sched_policy == DRM_SCHED_POLICY_FIFO) {
> > +	if (entity->sched_policy == DRM_SCHED_POLICY_FIFO) {
> 
> The entity (context) shouldn't have the "sched_policy" property.
> That property belong only to the scheduler.
> 

Sure. Will have to drop the union of sched_main & rq then.

> >  		struct drm_sched_job *next;
> >  
> >  		next = to_drm_sched_job(spsc_queue_peek(&entity->job_queue));
> > @@ -528,7 +545,7 @@ void drm_sched_entity_push_job(struct drm_sched_job *sched_job)
> >  		drm_sched_rq_add_entity(entity->rq, entity);
> >  		spin_unlock(&entity->rq_lock);
> >  
> > -		if (drm_sched_policy == DRM_SCHED_POLICY_FIFO)
> > +		if (entity->sched_policy == DRM_SCHED_POLICY_FIFO)
> >  			drm_sched_rq_update_fifo(entity, sched_job->submit_ts);
> >  
> >  		drm_sched_wakeup(entity->rq->sched);
> > diff --git a/drivers/gpu/drm/scheduler/sched_main.c b/drivers/gpu/drm/scheduler/sched_main.c
> > index 808008990721..77894976fa55 100644
> > --- a/drivers/gpu/drm/scheduler/sched_main.c
> > +++ b/drivers/gpu/drm/scheduler/sched_main.c
> > @@ -62,14 +62,14 @@
> >  #define to_drm_sched_job(sched_job)		\
> >  		container_of((sched_job), struct drm_sched_job, queue_node)
> >  
> > -int drm_sched_policy = DRM_SCHED_POLICY_FIFO;
> > +int default_drm_sched_policy = DRM_SCHED_POLICY_FIFO;
> >  
> >  /**
> >   * DOC: sched_policy (int)
> >   * Used to override default entities scheduling policy in a run queue.
> >   */
> >  MODULE_PARM_DESC(sched_policy, "Specify the scheduling policy for entities on a run-queue, " __stringify(DRM_SCHED_POLICY_RR) " = Round Robin, " __stringify(DRM_SCHED_POLICY_FIFO) " = FIFO (default).");
> > -module_param_named(sched_policy, drm_sched_policy, int, 0444);
> > +module_param_named(sched_policy, default_drm_sched_policy, int, 0444);
> >  
> >  static __always_inline bool drm_sched_entity_compare_before(struct rb_node *a,
> >  							    const struct rb_node *b)
> > @@ -173,7 +173,7 @@ void drm_sched_rq_remove_entity(struct drm_sched_rq *rq,
> >  	if (rq->current_entity == entity)
> >  		rq->current_entity = NULL;
> >  
> > -	if (drm_sched_policy == DRM_SCHED_POLICY_FIFO)
> > +	if (entity->sched_policy == DRM_SCHED_POLICY_FIFO)
> >  		drm_sched_rq_remove_fifo_locked(entity);
> >  
> >  	spin_unlock(&rq->lock);
> > @@ -931,7 +931,7 @@ drm_sched_select_entity(struct drm_gpu_scheduler *sched)
> >  
> >  	/* Kernel run queue has higher priority than normal run queue*/
> >  	for (i = DRM_SCHED_PRIORITY_COUNT - 1; i >= DRM_SCHED_PRIORITY_MIN; i--) {
> > -		entity = drm_sched_policy == DRM_SCHED_POLICY_FIFO ?
> > +		entity = sched->sched_policy == DRM_SCHED_POLICY_FIFO ?
> >  			drm_sched_rq_select_entity_fifo(&sched->sched_rq[i]) :
> >  			drm_sched_rq_select_entity_rr(&sched->sched_rq[i]);
> >  		if (entity)
> > @@ -1106,6 +1106,7 @@ static void drm_sched_main(struct work_struct *w)
> >   *		used
> >   * @score: optional score atomic shared with other schedulers
> >   * @name: name used for debugging
> > + * @sched_policy: schedule policy
> >   * @dev: target &struct device
> >   *
> >   * Return 0 on success, otherwise error code.
> > @@ -1115,9 +1116,15 @@ int drm_sched_init(struct drm_gpu_scheduler *sched,
> >  		   struct workqueue_struct *run_wq,
> >  		   unsigned hw_submission, unsigned hang_limit,
> >  		   long timeout, struct workqueue_struct *timeout_wq,
> > -		   atomic_t *score, const char *name, struct device *dev)
> > +		   atomic_t *score, const char *name,
> > +		   enum drm_sched_policy sched_policy,
> > +		   struct device *dev)
> >  {
> >  	int i;
> > +
> > +	if (sched_policy >= DRM_SCHED_POLICY_MAX)
> > +		return -EINVAL;
> > +
> >  	sched->ops = ops;
> >  	sched->hw_submission_limit = hw_submission;
> >  	sched->name = name;
> > @@ -1127,6 +1134,10 @@ int drm_sched_init(struct drm_gpu_scheduler *sched,
> >  	sched->hang_limit = hang_limit;
> >  	sched->score = score ? score : &sched->_score;
> >  	sched->dev = dev;
> > +	if (sched_policy == DRM_SCHED_POLICY_DEFAULT)
> > +		sched->sched_policy = default_drm_sched_policy;
> > +	else
> > +		sched->sched_policy = sched_policy;
> >  	for (i = DRM_SCHED_PRIORITY_MIN; i < DRM_SCHED_PRIORITY_COUNT; i++)
> >  		drm_sched_rq_init(sched, &sched->sched_rq[i]);
> >  
> > diff --git a/drivers/gpu/drm/v3d/v3d_sched.c b/drivers/gpu/drm/v3d/v3d_sched.c
> > index 38e092ea41e6..5e3fe77fa991 100644
> > --- a/drivers/gpu/drm/v3d/v3d_sched.c
> > +++ b/drivers/gpu/drm/v3d/v3d_sched.c
> > @@ -391,7 +391,8 @@ v3d_sched_init(struct v3d_dev *v3d)
> >  			     &v3d_bin_sched_ops, NULL,
> >  			     hw_jobs_limit, job_hang_limit,
> >  			     msecs_to_jiffies(hang_limit_ms), NULL,
> > -			     NULL, "v3d_bin", v3d->drm.dev);
> > +			     NULL, "v3d_bin", DRM_SCHED_POLICY_DEFAULT,
> > +			     v3d->drm.dev);
> >  	if (ret)
> >  		return ret;
> >  
> > @@ -399,7 +400,8 @@ v3d_sched_init(struct v3d_dev *v3d)
> >  			     &v3d_render_sched_ops, NULL,
> >  			     hw_jobs_limit, job_hang_limit,
> >  			     msecs_to_jiffies(hang_limit_ms), NULL,
> > -			     NULL, "v3d_render", v3d->drm.dev);
> > +			     ULL, "v3d_render", DRM_SCHED_POLICY_DEFAULT,
> > +			     v3d->drm.dev);
> >  	if (ret)
> >  		goto fail;
> >  
> > @@ -407,7 +409,8 @@ v3d_sched_init(struct v3d_dev *v3d)
> >  			     &v3d_tfu_sched_ops, NULL,
> >  			     hw_jobs_limit, job_hang_limit,
> >  			     msecs_to_jiffies(hang_limit_ms), NULL,
> > -			     NULL, "v3d_tfu", v3d->drm.dev);
> > +			     NULL, "v3d_tfu", DRM_SCHED_POLICY_DEFAULT,
> > +			     v3d->drm.dev);
> >  	if (ret)
> >  		goto fail;
> >  
> > @@ -416,7 +419,8 @@ v3d_sched_init(struct v3d_dev *v3d)
> >  				     &v3d_csd_sched_ops, NULL,
> >  				     hw_jobs_limit, job_hang_limit,
> >  				     msecs_to_jiffies(hang_limit_ms), NULL,
> > -				     NULL, "v3d_csd", v3d->drm.dev);
> > +				     NULL, "v3d_csd", DRM_SCHED_POLICY_DEFAULT,
> > +				     v3d->drm.dev);
> >  		if (ret)
> >  			goto fail;
> >  
> > @@ -424,7 +428,8 @@ v3d_sched_init(struct v3d_dev *v3d)
> >  				     &v3d_cache_clean_sched_ops, NULL,
> >  				     hw_jobs_limit, job_hang_limit,
> >  				     msecs_to_jiffies(hang_limit_ms), NULL,
> > -				     NULL, "v3d_cache_clean", v3d->drm.dev);
> > +				     NULL, "v3d_cache_clean",
> > +				     DRM_SCHED_POLICY_DEFAULT, v3d->drm.dev);
> >  		if (ret)
> >  			goto fail;
> >  	}
> > diff --git a/include/drm/gpu_scheduler.h b/include/drm/gpu_scheduler.h
> > index 98fb5f85eba6..39cb72b7fe5d 100644
> > --- a/include/drm/gpu_scheduler.h
> > +++ b/include/drm/gpu_scheduler.h
> > @@ -72,11 +72,15 @@ enum drm_sched_priority {
> >  	DRM_SCHED_PRIORITY_UNSET = -2
> >  };
> >  
> > -/* Used to chose between FIFO and RR jobs scheduling */
> > -extern int drm_sched_policy;
> > -
> > -#define DRM_SCHED_POLICY_RR    0
> > -#define DRM_SCHED_POLICY_FIFO  1
> > +/* Used to chose default scheduling policy*/
> > +extern int default_drm_sched_policy;
> > +
> > +enum drm_sched_policy {
> > +	DRM_SCHED_POLICY_DEFAULT,
> > +	DRM_SCHED_POLICY_RR,
> > +	DRM_SCHED_POLICY_FIFO,
> > +	DRM_SCHED_POLICY_MAX,
> > +};
> 
> Please don't use MAX. It is very confusing, as maximum and minimum values
> are values which can be attained, in literature and common use.
> For instance, "the maximum temperature today is 287K, also expect rains"
> means that that temperature will actually be attained.
> 
> Use, DRM_SCHED_POLICY_COUNT for instance, since for 0-based indexing,
> as that of C enums, the last element in the set is in fact the number of
> elements, i.e. the count of the set. (_NUM is also bad as it means
> "number" which could really be anything.)
> 
> So using DRM_SCHED_POLICY_COUNT is most clear.
>

Got it, will change.
 
> >  
> >  /**
> >   * struct drm_sched_entity - A wrapper around a job queue (typically
> > @@ -217,6 +221,9 @@ struct drm_sched_entity {
> >  	 */
> >  	bool 				stopped;
> >  
> > +	/** @sched_policy: Schedule policy for entity */
> > +	enum drm_sched_policy		sched_policy;
> > +
> 
> This creates data redundancy. "sched_policy" should only be found
> in the drm_gpu_scheduler structure. The context's tasks then get to run
> on a scheduler with such and such priority. We shouldn't have this here,
> only in drm_gpu_scheduler structure.
> 

Addressed above, will do.

Matt

> Regards,
> Luben
> 
> >  	/**
> >  	 * @entity_idle:
> >  	 *
> > @@ -489,6 +496,7 @@ struct drm_sched_backend_ops {
> >   *              guilty and it will no longer be considered for scheduling.
> >   * @score: score to help loadbalancer pick a idle sched
> >   * @_score: score used when the driver doesn't provide one
> > + * @sched_policy: Schedule policy for scheduler
> >   * @ready: marks if the underlying HW is ready to work
> >   * @free_guilty: A hit to time out handler to free the guilty job.
> >   * @pause_run_wq: pause queuing of @work_run on @run_wq
> > @@ -514,6 +522,7 @@ struct drm_gpu_scheduler {
> >  	int				hang_limit;
> >  	atomic_t                        *score;
> >  	atomic_t                        _score;
> > +	enum drm_sched_policy		sched_policy;
> >  	bool				ready;
> >  	bool				free_guilty;
> >  	bool				pause_run_wq;
> > @@ -525,7 +534,9 @@ int drm_sched_init(struct drm_gpu_scheduler *sched,
> >  		   struct workqueue_struct *run_wq,
> >  		   uint32_t hw_submission, unsigned hang_limit,
> >  		   long timeout, struct workqueue_struct *timeout_wq,
> > -		   atomic_t *score, const char *name, struct device *dev);
> > +		   atomic_t *score, const char *name,
> > +		   enum drm_sched_policy sched_policy,
> > +		   struct device *dev);
> >  
> >  void drm_sched_fini(struct drm_gpu_scheduler *sched);
> >  int drm_sched_job_init(struct drm_sched_job *job,
>