[PATCH v2] drm/sched: Further optimise drm_sched_entity_push_job

[Tvrtko Ursulin]

On 24/09/2024 10:45, Tvrtko Ursulin wrote:
> 
> On 24/09/2024 09:20, Christian König wrote:
>> Am 16.09.24 um 19:30 schrieb Tvrtko Ursulin:
>>> From: Tvrtko Ursulin <tvrtko.ursulin at igalia.com>
>>>
>>> Having removed one re-lock cycle on the entity->lock in a patch titled
>>> "drm/sched: Optimise drm_sched_entity_push_job", with only a tiny bit
>>> larger refactoring we can do the same optimisation on the rq->lock.
>>> (Currently both drm_sched_rq_add_entity() and
>>> drm_sched_rq_update_fifo_locked() take and release the same lock.)
>>>
>>> To achieve this we make drm_sched_rq_update_fifo_locked() and
>>> drm_sched_rq_add_entity() expect the rq->lock to be held.
>>>
>>> We also align drm_sched_rq_update_fifo_locked(),
>>> drm_sched_rq_add_entity() and
>>> drm_sched_rq_remove_fifo_locked() function signatures, by adding rq as a
>>> parameter to the latter.
>>>
>>> v2:
>>>   * Fix after rebase of the series.
>>>   * Avoid naming incosistency between drm_sched_rq_add/remove. 
>>> (Christian)
>>>
>>> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin at igalia.com>
>>> Cc: Christian König <christian.koenig at amd.com>
>>> Cc: Alex Deucher <alexander.deucher at amd.com>
>>> Cc: Luben Tuikov <ltuikov89 at gmail.com>
>>> Cc: Matthew Brost <matthew.brost at intel.com>
>>> Cc: Philipp Stanner <pstanner at redhat.com>
>>
>> Reviewed-by: Christian König <christian.koenig at amd.com>
> 
> Thanks!
> 
> Are you okay to pull into drm-misc-next or we should do some more 
> testing on this?
> 
> And/or should I resend the series once more in it's entirety so this v2 
> is not a reply-to to the original?

I have to respin for the drm_sched_wakeup fix that landed.

Regards,

Tvrtko

> 
> Regards,
> 
> Tvrtko
> 
>>
>>> ---
>>>   drivers/gpu/drm/scheduler/sched_entity.c | 12 ++++++++--
>>>   drivers/gpu/drm/scheduler/sched_main.c   | 29 ++++++++++++------------
>>>   include/drm/gpu_scheduler.h              |  3 ++-
>>>   3 files changed, 26 insertions(+), 18 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/scheduler/sched_entity.c 
>>> b/drivers/gpu/drm/scheduler/sched_entity.c
>>> index d982cebc6bee..8ace1f1ea66b 100644
>>> --- a/drivers/gpu/drm/scheduler/sched_entity.c
>>> +++ b/drivers/gpu/drm/scheduler/sched_entity.c
>>> @@ -515,9 +515,14 @@ struct drm_sched_job 
>>> *drm_sched_entity_pop_job(struct drm_sched_entity *entity)
>>>           next = to_drm_sched_job(spsc_queue_peek(&entity->job_queue));
>>>           if (next) {
>>> +            struct drm_sched_rq *rq;
>>> +
>>>               spin_lock(&entity->lock);
>>> -            drm_sched_rq_update_fifo_locked(entity,
>>> +            rq = entity->rq;
>>> +            spin_lock(&rq->lock);
>>> +            drm_sched_rq_update_fifo_locked(entity, rq,
>>>                               next->submit_ts);
>>> +            spin_unlock(&rq->lock);
>>>               spin_unlock(&entity->lock);
>>>           }
>>>       }
>>> @@ -618,11 +623,14 @@ void drm_sched_entity_push_job(struct 
>>> drm_sched_job *sched_job)
>>>           sched = rq->sched;
>>>           atomic_inc(sched->score);
>>> +
>>> +        spin_lock(&rq->lock);
>>>           drm_sched_rq_add_entity(rq, entity);
>>>           if (drm_sched_policy == DRM_SCHED_POLICY_FIFO)
>>> -            drm_sched_rq_update_fifo_locked(entity, submit_ts);
>>> +            drm_sched_rq_update_fifo_locked(entity, rq, submit_ts);
>>> +        spin_unlock(&rq->lock);
>>>           spin_unlock(&entity->lock);
>>>           drm_sched_wakeup(sched, entity);
>>> diff --git a/drivers/gpu/drm/scheduler/sched_main.c 
>>> b/drivers/gpu/drm/scheduler/sched_main.c
>>> index 18a952f73ecb..5c83fb92bb89 100644
>>> --- a/drivers/gpu/drm/scheduler/sched_main.c
>>> +++ b/drivers/gpu/drm/scheduler/sched_main.c
>>> @@ -153,17 +153,18 @@ static __always_inline bool 
>>> drm_sched_entity_compare_before(struct rb_node *a,
>>>       return ktime_before(ent_a->oldest_job_waiting, 
>>> ent_b->oldest_job_waiting);
>>>   }
>>> -static inline void drm_sched_rq_remove_fifo_locked(struct 
>>> drm_sched_entity *entity)
>>> +static void drm_sched_rq_remove_fifo_locked(struct drm_sched_entity 
>>> *entity,
>>> +                        struct drm_sched_rq *rq)
>>>   {
>>> -    struct drm_sched_rq *rq = entity->rq;
>>> -
>>>       if (!RB_EMPTY_NODE(&entity->rb_tree_node)) {
>>>           rb_erase_cached(&entity->rb_tree_node, &rq->rb_tree_root);
>>>           RB_CLEAR_NODE(&entity->rb_tree_node);
>>>       }
>>>   }
>>> -void drm_sched_rq_update_fifo_locked(struct drm_sched_entity 
>>> *entity, ktime_t ts)
>>> +void drm_sched_rq_update_fifo_locked(struct drm_sched_entity *entity,
>>> +                     struct drm_sched_rq *rq,
>>> +                     ktime_t ts)
>>>   {
>>>       /*
>>>        * Both locks need to be grabbed, one to protect from 
>>> entity->rq change
>>> @@ -171,17 +172,14 @@ void drm_sched_rq_update_fifo_locked(struct 
>>> drm_sched_entity *entity, ktime_t ts
>>>        * other to update the rb tree structure.
>>>        */
>>>       lockdep_assert_held(&entity->lock);
>>> +    lockdep_assert_held(&rq->lock);
>>> -    spin_lock(&entity->rq->lock);
>>> -
>>> -    drm_sched_rq_remove_fifo_locked(entity);
>>> +    drm_sched_rq_remove_fifo_locked(entity, rq);
>>>       entity->oldest_job_waiting = ts;
>>> -    rb_add_cached(&entity->rb_tree_node, &entity->rq->rb_tree_root,
>>> +    rb_add_cached(&entity->rb_tree_node, &rq->rb_tree_root,
>>>                 drm_sched_entity_compare_before);
>>> -
>>> -    spin_unlock(&entity->rq->lock);
>>>   }
>>>   /**
>>> @@ -213,15 +211,14 @@ 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)
>>>   {
>>> +    lockdep_assert_held(&entity->lock);
>>> +    lockdep_assert_held(&rq->lock);
>>> +
>>>       if (!list_empty(&entity->list))
>>>           return;
>>> -    spin_lock(&rq->lock);
>>> -
>>>       atomic_inc(rq->sched->score);
>>>       list_add_tail(&entity->list, &rq->entities);
>>> -
>>> -    spin_unlock(&rq->lock);
>>>   }
>>>   /**
>>> @@ -235,6 +232,8 @@ 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)
>>>   {
>>> +    lockdep_assert_held(&entity->lock);
>>> +
>>>       if (list_empty(&entity->list))
>>>           return;
>>> @@ -247,7 +246,7 @@ void drm_sched_rq_remove_entity(struct 
>>> drm_sched_rq *rq,
>>>           rq->current_entity = NULL;
>>>       if (drm_sched_policy == DRM_SCHED_POLICY_FIFO)
>>> -        drm_sched_rq_remove_fifo_locked(entity);
>>> +        drm_sched_rq_remove_fifo_locked(entity, rq);
>>>       spin_unlock(&rq->lock);
>>>   }
>>> diff --git a/include/drm/gpu_scheduler.h b/include/drm/gpu_scheduler.h
>>> index 80198e6cf537..b21806d5a8eb 100644
>>> --- a/include/drm/gpu_scheduler.h
>>> +++ b/include/drm/gpu_scheduler.h
>>> @@ -596,7 +596,8 @@ 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);
>>> -void drm_sched_rq_update_fifo_locked(struct drm_sched_entity 
>>> *entity, ktime_t ts);
>>> +void drm_sched_rq_update_fifo_locked(struct drm_sched_entity *entity,
>>> +                     struct drm_sched_rq *rq, ktime_t ts);
>>>   int drm_sched_entity_init(struct drm_sched_entity *entity,
>>>                 enum drm_sched_priority priority,
>>