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

[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;
+	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) {
 		/* 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);
-- 
2.14.3