[PATCH 4/4] drm/scheduler: move idle entities to scheduler with less load

[Christian König]

Am 31.07.2018 um 12:37 schrieb Nayan Deshmukh:
> This is the first attempt to move entities between schedulers to
> have dynamic load balancing. We just move entities with no jobs for
> now as moving the ones with jobs will lead to other compilcations
> like ensuring that the other scheduler does not remove a job from
> the current entity while we are moving.
>
> Signed-off-by: Nayan Deshmukh <nayan26deshmukh at gmail.com>
> ---
>   drivers/gpu/drm/scheduler/gpu_scheduler.c | 25 ++++++++++++++++++++-----
>   1 file changed, 20 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/gpu/drm/scheduler/gpu_scheduler.c b/drivers/gpu/drm/scheduler/gpu_scheduler.c
> index c67f65ad8f15..f665a84d48ef 100644
> --- a/drivers/gpu/drm/scheduler/gpu_scheduler.c
> +++ b/drivers/gpu/drm/scheduler/gpu_scheduler.c
> @@ -540,6 +540,8 @@ drm_sched_entity_pop_job(struct drm_sched_entity *entity)
>   	if (!sched_job)
>   		return NULL;
>   
> +	sched_job->sched = sched;
> +	sched_job->s_fence->sched = sched;
>   	while ((entity->dependency = sched->ops->dependency(sched_job, entity)))
>   		if (drm_sched_entity_add_dependency_cb(entity))
>   			return NULL;
> @@ -570,16 +572,29 @@ drm_sched_entity_pop_job(struct drm_sched_entity *entity)
>   void drm_sched_entity_push_job(struct drm_sched_job *sched_job,
>   			       struct drm_sched_entity *entity)
>   {
> -	struct drm_gpu_scheduler *sched = sched_job->sched;
> -	bool first = false;
> +	struct drm_gpu_scheduler *sched = entity->rq->sched;

Is the local "sched" variable actually still used?

Might be a good idea to drop that since we potentially changing the 
scheduler/rq.


> +	struct drm_sched_rq *rq = entity->rq;
> +	bool first = false, reschedule, idle;
>   
> -	trace_drm_sched_job(sched_job, entity);
> +	idle = entity->last_scheduled == NULL ||
> +		dma_fence_is_signaled(entity->last_scheduled);
> +	first = spsc_queue_count(&entity->job_queue) == 0;
> +	reschedule = idle && first && (entity->num_rq_list > 1);
> +
> +	if (reschedule) {
> +		rq = drm_sched_entity_get_free_sched(entity);
> +		spin_lock(&entity->rq_lock);
> +		drm_sched_rq_remove_entity(entity->rq, entity);
> +		entity->rq = rq;
> +		spin_unlock(&entity->rq_lock);
> +	}
>   
> +	trace_drm_sched_job(sched_job, entity);
>   	atomic_inc(&entity->rq->sched->num_jobs);
>   	first = spsc_queue_push(&entity->job_queue, &sched_job->queue_node);
>   
>   	/* first job wakes up scheduler */
> -	if (first) {
> +	if (first || reschedule) {

You can drop that extra check since we can only rescheduler when there 
wasn't any jobs in the entity.

Christian.

>   		/* Add the entity to the run queue */
>   		spin_lock(&entity->rq_lock);
>   		if (!entity->rq) {
> @@ -589,7 +604,7 @@ 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);
> -		drm_sched_wakeup(sched);
> +		drm_sched_wakeup(entity->rq->sched);
>   	}
>   }
>   EXPORT_SYMBOL(drm_sched_entity_push_job);