Re: [PATCH v2] drm/sched: Further optimise drm_sched_entity_push_job

[Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxxx>]

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@xxxxxxxxxx>
> > >
> > > 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@xxxxxxxxxx>
> > > Cc: Christian König <christian.koenig@xxxxxxx>
> > > Cc: Alex Deucher <alexander.deucher@xxxxxxx>
> > > Cc: Luben Tuikov <ltuikov89@xxxxxxxxx>
> > > Cc: Matthew Brost <matthew.brost@xxxxxxxxx>
> > > Cc: Philipp Stanner <pstanner@xxxxxxxxxx>
> >
> > Reviewed-by: Christian König <christian.koenig@xxxxxxx>
>
> 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,