Re: [PATCH 1/2] drm/scheduler: bind job earlier to scheduler

[Nayan Deshmukh <nayan26deshmukh@xxxxxxxxx>]

Hi Christian,

On Mon, Aug 6, 2018 at 5:49 PM Christian König <ckoenig.leichtzumerken@xxxxxxxxx> wrote:

Update job earlier with the scheduler it is supposed to be scheduled on.

Otherwise we could incorrectly optimize dependencies when moving an
entity from one scheduler to another.

I don't think change is really required, the old code should work fine. Read below for more comments.
 

Signed-off-by: Christian König <christian.koenig@xxxxxxx>
---
 drivers/gpu/drm/scheduler/gpu_scheduler.c | 4 ++--
 drivers/gpu/drm/scheduler/sched_fence.c   | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/scheduler/gpu_scheduler.c b/drivers/gpu/drm/scheduler/gpu_scheduler.c
index 65078dd3c82c..029863726c99 100644
--- a/drivers/gpu/drm/scheduler/gpu_scheduler.c
+++ b/drivers/gpu/drm/scheduler/gpu_scheduler.c
@@ -533,8 +533,6 @@ 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)))

The job should have the correct scheduler before the sched->oops->dependency() function is called for the first time. Hence I placed the assignment here.

It might also be that I am missing some case so please let me know if such a case exists where this might lead to wrong optimization.

Regards,

Nayan

                if (drm_sched_entity_add_dependency_cb(entity))
                        return NULL;
@@ -581,6 +579,8 @@ void drm_sched_entity_push_job(struct drm_sched_job *sched_job,
                spin_unlock(&entity->rq_lock);
        }

+       sched_job->sched = entity->rq->sched;
+       sched_job->s_fence->sched = entity->rq->sched;
        trace_drm_sched_job(sched_job, entity);
        atomic_inc(&entity->rq->sched->num_jobs);
        WRITE_ONCE(entity->last_user, current->group_leader);
diff --git a/drivers/gpu/drm/scheduler/sched_fence.c b/drivers/gpu/drm/scheduler/sched_fence.c
index 4029312fdd81..6dab18d288d7 100644
--- a/drivers/gpu/drm/scheduler/sched_fence.c
+++ b/drivers/gpu/drm/scheduler/sched_fence.c
@@ -172,7 +172,7 @@ struct drm_sched_fence *drm_sched_fence_create(struct drm_sched_entity *entity,
                return NULL;

        fence->owner = owner;
-       fence->sched = entity->rq->sched;
+       fence->sched = NULL;
        spin_lock_init(&fence->lock);

        seq = atomic_inc_return(&entity->fence_seq);
--
2.14.1

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