[PATCH v2] drm/sched: Further optimise drm_sched_entity_push_job

[Tvrtko Ursulin]

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?

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,
>