[Intel-xe] [PATCH v2 03/31] drm/sched: Add DRM_SCHED_POLICY_SINGLE_ENTITY scheduling policy

Thomas Hellström thomas.hellstrom at linux.intel.com
Mon May 8 12:40:24 UTC 2023


An question below, with that addressed (possibly without change)

although I'm not a scheduler expert and we should ideally have 
additional reviewers,

Reviewed-by: Thomas Hellström <thomas.hellstrom at linux.intel.com>

On 5/2/23 02:16, Matthew Brost wrote:
> DRM_SCHED_POLICY_SINGLE_ENTITY creates a 1 to 1 relationship between
> scheduler and entity. No priorities or run queue used in this mode.
> Intended for devices with firmware schedulers.
>
> Signed-off-by: Matthew Brost <matthew.brost at intel.com>
> ---
>   drivers/gpu/drm/scheduler/sched_entity.c | 64 +++++++++++++++++++-----
>   drivers/gpu/drm/scheduler/sched_fence.c  |  2 +-
>   drivers/gpu/drm/scheduler/sched_main.c   | 63 ++++++++++++++++++++---
>   include/drm/gpu_scheduler.h              |  8 +++
>   4 files changed, 115 insertions(+), 22 deletions(-)
>
> diff --git a/drivers/gpu/drm/scheduler/sched_entity.c b/drivers/gpu/drm/scheduler/sched_entity.c
> index 2300b2fc06ab..8b70900c54cc 100644
> --- a/drivers/gpu/drm/scheduler/sched_entity.c
> +++ b/drivers/gpu/drm/scheduler/sched_entity.c
> @@ -83,6 +83,7 @@ int drm_sched_entity_init(struct drm_sched_entity *entity,
>   	memset(entity, 0, sizeof(struct drm_sched_entity));
>   	INIT_LIST_HEAD(&entity->list);
>   	entity->rq = NULL;
> +	entity->single_sched = NULL;
>   	entity->guilty = guilty;
>   	entity->num_sched_list = num_sched_list;
>   	entity->priority = priority;
> @@ -91,7 +92,15 @@ int drm_sched_entity_init(struct drm_sched_entity *entity,
>   	RB_CLEAR_NODE(&entity->rb_tree_node);
>   
>   	if(num_sched_list) {
> -		entity->rq = &sched_list[0]->sched_rq[entity->priority];
> +		if (sched_list[0]->sched_policy !=
> +		    DRM_SCHED_POLICY_SINGLE_ENTITY) {
> +			entity->rq = &sched_list[0]->sched_rq[entity->priority];
> +		} else {
> +			if (num_sched_list != 1 || sched_list[0]->single_entity)
> +				return -EINVAL;
> +			sched_list[0]->single_entity = entity;
> +			entity->single_sched = sched_list[0];
> +		}
>   	}
>   
>   	init_completion(&entity->entity_idle);
> @@ -125,7 +134,8 @@ void drm_sched_entity_modify_sched(struct drm_sched_entity *entity,
>   				    struct drm_gpu_scheduler **sched_list,
>   				    unsigned int num_sched_list)
>   {
> -	WARN_ON(!num_sched_list || !sched_list);

Is there a way to get to the drm device so we can use drm_WARN_ON() here 
and below? I figure not?

Thanks,

Thomas


> +	WARN_ON(!num_sched_list || !sched_list ||
> +		!!entity->single_sched);
>   
>   	entity->sched_list = sched_list;
>   	entity->num_sched_list = num_sched_list;
> @@ -195,13 +205,15 @@ static void drm_sched_entity_kill(struct drm_sched_entity *entity)
>   {
>   	struct drm_sched_job *job;
>   	struct dma_fence *prev;
> +	bool single_entity = !!entity->single_sched;
>   
> -	if (!entity->rq)
> +	if (!entity->rq && !single_entity)
>   		return;
>   
>   	spin_lock(&entity->rq_lock);
>   	entity->stopped = true;
> -	drm_sched_rq_remove_entity(entity->rq, entity);
> +	if (!single_entity)
> +		drm_sched_rq_remove_entity(entity->rq, entity);
>   	spin_unlock(&entity->rq_lock);
>   
>   	/* Make sure this entity is not used by the scheduler at the moment */
> @@ -223,6 +235,20 @@ static void drm_sched_entity_kill(struct drm_sched_entity *entity)
>   	dma_fence_put(prev);
>   }
>   
> +/**
> + * drm_sched_entity_to_scheduler - Schedule entity to GPU scheduler
> + * @entity: scheduler entity
> + *
> + * Returns GPU scheduler for the entity
> + */
> +struct drm_gpu_scheduler *
> +drm_sched_entity_to_scheduler(struct drm_sched_entity *entity)
> +{
> +	bool single_entity = !!entity->single_sched;
> +
> +	return single_entity ? entity->single_sched : entity->rq->sched;
> +}
> +
>   /**
>    * drm_sched_entity_flush - Flush a context entity
>    *
> @@ -240,11 +266,12 @@ long drm_sched_entity_flush(struct drm_sched_entity *entity, long timeout)
>   	struct drm_gpu_scheduler *sched;
>   	struct task_struct *last_user;
>   	long ret = timeout;
> +	bool single_entity = !!entity->single_sched;
>   
> -	if (!entity->rq)
> +	if (!entity->rq && !single_entity)
>   		return 0;
>   
> -	sched = entity->rq->sched;
> +	sched = drm_sched_entity_to_scheduler(entity);
>   	/**
>   	 * The client will not queue more IBs during this fini, consume existing
>   	 * queued IBs or discard them on SIGKILL
> @@ -337,7 +364,7 @@ static void drm_sched_entity_wakeup(struct dma_fence *f,
>   		container_of(cb, struct drm_sched_entity, cb);
>   
>   	drm_sched_entity_clear_dep(f, cb);
> -	drm_sched_wakeup(entity->rq->sched);
> +	drm_sched_wakeup(drm_sched_entity_to_scheduler(entity));
>   }
>   
>   /**
> @@ -351,6 +378,8 @@ static void drm_sched_entity_wakeup(struct dma_fence *f,
>   void drm_sched_entity_set_priority(struct drm_sched_entity *entity,
>   				   enum drm_sched_priority priority)
>   {
> +	WARN_ON(!!entity->single_sched);
> +
>   	spin_lock(&entity->rq_lock);
>   	entity->priority = priority;
>   	spin_unlock(&entity->rq_lock);
> @@ -363,7 +392,7 @@ EXPORT_SYMBOL(drm_sched_entity_set_priority);
>    */
>   static bool drm_sched_entity_add_dependency_cb(struct drm_sched_entity *entity)
>   {
> -	struct drm_gpu_scheduler *sched = entity->rq->sched;
> +	struct drm_gpu_scheduler *sched = drm_sched_entity_to_scheduler(entity);
>   	struct dma_fence *fence = entity->dependency;
>   	struct drm_sched_fence *s_fence;
>   
> @@ -456,7 +485,8 @@ 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 (entity->rq->sched->sched_policy == DRM_SCHED_POLICY_FIFO) {
> +	if (drm_sched_entity_to_scheduler(entity)->sched_policy ==
> +	    DRM_SCHED_POLICY_FIFO) {
>   		struct drm_sched_job *next;
>   
>   		next = to_drm_sched_job(spsc_queue_peek(&entity->job_queue));
> @@ -473,6 +503,8 @@ void drm_sched_entity_select_rq(struct drm_sched_entity *entity)
>   	struct drm_gpu_scheduler *sched;
>   	struct drm_sched_rq *rq;
>   
> +	WARN_ON(!!entity->single_sched);
> +
>   	/* single possible engine and already selected */
>   	if (!entity->sched_list)
>   		return;
> @@ -522,16 +554,21 @@ void drm_sched_entity_select_rq(struct drm_sched_entity *entity)
>   void drm_sched_entity_push_job(struct drm_sched_job *sched_job)
>   {
>   	struct drm_sched_entity *entity = sched_job->entity;
> +	bool single_entity = !!entity->single_sched;
>   	bool first;
>   
>   	trace_drm_sched_job(sched_job, entity);
> -	atomic_inc(entity->rq->sched->score);
> +	if (!single_entity)
> +		atomic_inc(entity->rq->sched->score);
>   	WRITE_ONCE(entity->last_user, current->group_leader);
>   	first = spsc_queue_push(&entity->job_queue, &sched_job->queue_node);
>   	sched_job->submit_ts = ktime_get();
>   
>   	/* first job wakes up scheduler */
>   	if (first) {
> +		struct drm_gpu_scheduler *sched =
> +			drm_sched_entity_to_scheduler(entity);
> +
>   		/* Add the entity to the run queue */
>   		spin_lock(&entity->rq_lock);
>   		if (entity->stopped) {
> @@ -541,13 +578,14 @@ void drm_sched_entity_push_job(struct drm_sched_job *sched_job)
>   			return;
>   		}
>   
> -		drm_sched_rq_add_entity(entity->rq, entity);
> +		if (!single_entity)
> +			drm_sched_rq_add_entity(entity->rq, entity);
>   		spin_unlock(&entity->rq_lock);
>   
> -		if (entity->rq->sched->sched_policy == DRM_SCHED_POLICY_FIFO)
> +		if (sched->sched_policy == DRM_SCHED_POLICY_FIFO)
>   			drm_sched_rq_update_fifo(entity, sched_job->submit_ts);
>   
> -		drm_sched_wakeup(entity->rq->sched);
> +		drm_sched_wakeup(sched);
>   	}
>   }
>   EXPORT_SYMBOL(drm_sched_entity_push_job);
> diff --git a/drivers/gpu/drm/scheduler/sched_fence.c b/drivers/gpu/drm/scheduler/sched_fence.c
> index 7fd869520ef2..1ba5056851dd 100644
> --- a/drivers/gpu/drm/scheduler/sched_fence.c
> +++ b/drivers/gpu/drm/scheduler/sched_fence.c
> @@ -167,7 +167,7 @@ void drm_sched_fence_init(struct drm_sched_fence *fence,
>   {
>   	unsigned seq;
>   
> -	fence->sched = entity->rq->sched;
> +	fence->sched = drm_sched_entity_to_scheduler(entity);
>   	seq = atomic_inc_return(&entity->fence_seq);
>   	dma_fence_init(&fence->scheduled, &drm_sched_fence_ops_scheduled,
>   		       &fence->lock, entity->fence_context, seq);
> diff --git a/drivers/gpu/drm/scheduler/sched_main.c b/drivers/gpu/drm/scheduler/sched_main.c
> index 6777a2db554f..870568d94f1f 100644
> --- a/drivers/gpu/drm/scheduler/sched_main.c
> +++ b/drivers/gpu/drm/scheduler/sched_main.c
> @@ -32,7 +32,8 @@
>    * backend operations to the scheduler like submitting a job to hardware run queue,
>    * returning the dependencies of a job etc.
>    *
> - * The organisation of the scheduler is the following:
> + * The organisation of the scheduler is the following for scheduling policies
> + * DRM_SCHED_POLICY_RR and DRM_SCHED_POLICY_FIFO:
>    *
>    * 1. Each hw run queue has one scheduler
>    * 2. Each scheduler has multiple run queues with different priorities
> @@ -41,7 +42,22 @@
>    * 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.
> + * The organisation of the scheduler is the following for scheduling policy
> + * DRM_SCHED_POLICY_SINGLE_ENTITY:
> + *
> + * 1. One to one relationship between scheduler and entity
> + * 2. No priorities implemented per scheduler (single job queue)
> + * 3. No run queues in scheduler rather jobs are directly dequeued from entity
> + * 4. The entity maintains 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
> + * regardless of scheduling policy.
> + *
> + * A policy of DRM_SCHED_POLICY_RR or DRM_SCHED_POLICY_FIFO is expected to used
> + * when the KMD is scheduling directly on the hardware while a scheduling policy
> + * of DRM_SCHED_POLICY_SINGLE_ENTITY is expected to be used when there is a
> + * firmare scheduler.
>    */
>   
>   #include <linux/wait.h>
> @@ -92,6 +108,8 @@ static inline void drm_sched_rq_remove_fifo_locked(struct drm_sched_entity *enti
>   
>   void drm_sched_rq_update_fifo(struct drm_sched_entity *entity, ktime_t ts)
>   {
> +	WARN_ON(!!entity->single_sched);
> +
>   	/*
>   	 * Both locks need to be grabbed, one to protect from entity->rq change
>   	 * for entity from within concurrent drm_sched_entity_select_rq and the
> @@ -122,6 +140,8 @@ void drm_sched_rq_update_fifo(struct drm_sched_entity *entity, ktime_t ts)
>   static void drm_sched_rq_init(struct drm_gpu_scheduler *sched,
>   			      struct drm_sched_rq *rq)
>   {
> +	WARN_ON(sched->sched_policy == DRM_SCHED_POLICY_SINGLE_ENTITY);
> +
>   	spin_lock_init(&rq->lock);
>   	INIT_LIST_HEAD(&rq->entities);
>   	rq->rb_tree_root = RB_ROOT_CACHED;
> @@ -140,6 +160,8 @@ static void drm_sched_rq_init(struct drm_gpu_scheduler *sched,
>   void drm_sched_rq_add_entity(struct drm_sched_rq *rq,
>   			     struct drm_sched_entity *entity)
>   {
> +	WARN_ON(!!entity->single_sched);
> +
>   	if (!list_empty(&entity->list))
>   		return;
>   
> @@ -162,6 +184,8 @@ void drm_sched_rq_add_entity(struct drm_sched_rq *rq,
>   void drm_sched_rq_remove_entity(struct drm_sched_rq *rq,
>   				struct drm_sched_entity *entity)
>   {
> +	WARN_ON(!!entity->single_sched);
> +
>   	if (list_empty(&entity->list))
>   		return;
>   
> @@ -691,7 +715,7 @@ int drm_sched_job_init(struct drm_sched_job *job,
>   		       struct drm_sched_entity *entity,
>   		       void *owner)
>   {
> -	if (!entity->rq)
> +	if (!entity->rq && !entity->single_sched)
>   		return -ENOENT;
>   
>   	job->entity = entity;
> @@ -724,13 +748,16 @@ void drm_sched_job_arm(struct drm_sched_job *job)
>   {
>   	struct drm_gpu_scheduler *sched;
>   	struct drm_sched_entity *entity = job->entity;
> +	bool single_entity = !!entity->single_sched;
>   
>   	BUG_ON(!entity);
> -	drm_sched_entity_select_rq(entity);
> -	sched = entity->rq->sched;
> +	if (!single_entity)
> +		drm_sched_entity_select_rq(entity);
> +	sched = drm_sched_entity_to_scheduler(entity);
>   
>   	job->sched = sched;
> -	job->s_priority = entity->rq - sched->sched_rq;
> +	if (!single_entity)
> +		job->s_priority = entity->rq - sched->sched_rq;
>   	job->id = atomic64_inc_return(&sched->job_id_count);
>   
>   	drm_sched_fence_init(job->s_fence, job->entity);
> @@ -954,6 +981,13 @@ drm_sched_select_entity(struct drm_gpu_scheduler *sched)
>   	if (!drm_sched_ready(sched))
>   		return NULL;
>   
> +	if (sched->single_entity) {
> +		if (drm_sched_entity_is_ready(sched->single_entity))
> +			return sched->single_entity;
> +
> +		return NULL;
> +	}
> +
>   	/* Kernel run queue has higher priority than normal run queue*/
>   	for (i = DRM_SCHED_PRIORITY_COUNT - 1; i >= DRM_SCHED_PRIORITY_MIN; i--) {
>   		entity = sched->sched_policy == DRM_SCHED_POLICY_FIFO ?
> @@ -1210,6 +1244,7 @@ int drm_sched_init(struct drm_gpu_scheduler *sched,
>   		return -EINVAL;
>   
>   	sched->ops = ops;
> +	sched->single_entity = NULL;
>   	sched->hw_submission_limit = hw_submission;
>   	sched->name = name;
>   	sched->run_wq = run_wq ? : system_wq;
> @@ -1222,7 +1257,9 @@ int drm_sched_init(struct drm_gpu_scheduler *sched,
>   		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++)
> +	for (i = DRM_SCHED_PRIORITY_MIN; sched_policy !=
> +	     DRM_SCHED_POLICY_SINGLE_ENTITY && i < DRM_SCHED_PRIORITY_COUNT;
> +	     i++)
>   		drm_sched_rq_init(sched, &sched->sched_rq[i]);
>   
>   	init_waitqueue_head(&sched->job_scheduled);
> @@ -1255,7 +1292,15 @@ void drm_sched_fini(struct drm_gpu_scheduler *sched)
>   
>   	drm_sched_run_wq_stop(sched);
>   
> -	for (i = DRM_SCHED_PRIORITY_COUNT - 1; i >= DRM_SCHED_PRIORITY_MIN; i--) {
> +	if (sched->single_entity) {
> +		spin_lock(&sched->single_entity->rq_lock);
> +		sched->single_entity->stopped = true;
> +		spin_unlock(&sched->single_entity->rq_lock);
> +	}
> +
> +	for (i = DRM_SCHED_PRIORITY_COUNT - 1; sched->sched_policy !=
> +	     DRM_SCHED_POLICY_SINGLE_ENTITY && i >= DRM_SCHED_PRIORITY_MIN;
> +	     i--) {
>   		struct drm_sched_rq *rq = &sched->sched_rq[i];
>   
>   		if (!rq)
> @@ -1299,6 +1344,8 @@ void drm_sched_increase_karma(struct drm_sched_job *bad)
>   	struct drm_sched_entity *entity;
>   	struct drm_gpu_scheduler *sched = bad->sched;
>   
> +	WARN_ON(sched->sched_policy == DRM_SCHED_POLICY_SINGLE_ENTITY);
> +
>   	/* don't change @bad's karma if it's from KERNEL RQ,
>   	 * because sometimes GPU hang would cause kernel jobs (like VM updating jobs)
>   	 * corrupt but keep in mind that kernel jobs always considered good.
> diff --git a/include/drm/gpu_scheduler.h b/include/drm/gpu_scheduler.h
> index 3df801401028..669d6520cd3a 100644
> --- a/include/drm/gpu_scheduler.h
> +++ b/include/drm/gpu_scheduler.h
> @@ -70,6 +70,7 @@ enum drm_sched_policy {
>   	DRM_SCHED_POLICY_DEFAULT,
>   	DRM_SCHED_POLICY_RR,
>   	DRM_SCHED_POLICY_FIFO,
> +	DRM_SCHED_POLICY_SINGLE_ENTITY,
>   	DRM_SCHED_POLICY_COUNT,
>   };
>   
> @@ -103,6 +104,9 @@ struct drm_sched_entity {
>   	 */
>   	struct drm_sched_rq		*rq;
>   
> +	/** @single_sched: Single scheduler */
> +	struct drm_gpu_scheduler	*single_sched;
> +
>   	/**
>   	 * @sched_list:
>   	 *
> @@ -488,6 +492,7 @@ struct drm_sched_backend_ops {
>    * struct drm_gpu_scheduler - scheduler instance-specific data
>    *
>    * @ops: backend operations provided by the driver.
> + * @single_entity: Single entity for the scheduler
>    * @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.
> @@ -519,6 +524,7 @@ struct drm_sched_backend_ops {
>    */
>   struct drm_gpu_scheduler {
>   	const struct drm_sched_backend_ops	*ops;
> +	struct drm_sched_entity		*single_entity;
>   	uint32_t			hw_submission_limit;
>   	long				timeout;
>   	const char			*name;
> @@ -604,6 +610,8 @@ int drm_sched_entity_init(struct drm_sched_entity *entity,
>   			  struct drm_gpu_scheduler **sched_list,
>   			  unsigned int num_sched_list,
>   			  atomic_t *guilty);
> +struct drm_gpu_scheduler *
> +drm_sched_entity_to_scheduler(struct drm_sched_entity *entity);
>   long drm_sched_entity_flush(struct drm_sched_entity *entity, long timeout);
>   void drm_sched_entity_fini(struct drm_sched_entity *entity);
>   void drm_sched_entity_destroy(struct drm_sched_entity *entity);


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