Re: [PATCH] drm/sched: Drain all entities in DRM sched run job worker

[Matthew Brost <matthew.brost@intel.com>]

On Thu, Jan 25, 2024 at 10:24:24AM +0100, Vlastimil Babka wrote:
> On 1/24/24 22:08, Matthew Brost wrote:
> > All entities must be drained in the DRM scheduler run job worker to
> > avoid the following case. An entity found that is ready, no job found
> > ready on entity, and run job worker goes idle with other entities + jobs
> > ready. Draining all ready entities (i.e. loop over all ready entities)
> > in the run job worker ensures all job that are ready will be scheduled.
> > 
> > Cc: Thorsten Leemhuis <regressions@leemhuis.info>
> > Reported-by: Mikhail Gavrilov <mikhail.v.gavrilov@gmail.com>
> > Closes: https://lore.kernel.org/all/CABXGCsM2VLs489CH-vF-1539-s3in37=bwuOWtoeeE+q26zE+Q@mail.gmail.com/
> > Reported-and-tested-by: Mario Limonciello <mario.limonciello@amd.com>
> > Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/3124
> > Link: https://lore.kernel.org/all/20240123021155.2775-1-mario.limonciello@amd.com/
> > Reported-by: Vlastimil Babka <vbabka@suse.cz>
> 
> Can change to Reported-and-tested-by: Vlastimil Babka <vbabka@suse.cz>
> 

+1, got it.

Matt

> Thanks!
> 
> > Closes: https://lore.kernel.org/dri-devel/05ddb2da-b182-4791-8ef7-82179fd159a8@amd.com/T/#m0c31d4d1b9ae9995bb880974c4f1dbaddc33a48a
> > Signed-off-by: Matthew Brost <matthew.brost@intel.com>
> > ---
> >  drivers/gpu/drm/scheduler/sched_main.c | 15 +++++++--------
> >  1 file changed, 7 insertions(+), 8 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/scheduler/sched_main.c b/drivers/gpu/drm/scheduler/sched_main.c
> > index 550492a7a031..85f082396d42 100644
> > --- a/drivers/gpu/drm/scheduler/sched_main.c
> > +++ b/drivers/gpu/drm/scheduler/sched_main.c
> > @@ -1178,21 +1178,20 @@ static void drm_sched_run_job_work(struct work_struct *w)
> >  	struct drm_sched_entity *entity;
> >  	struct dma_fence *fence;
> >  	struct drm_sched_fence *s_fence;
> > -	struct drm_sched_job *sched_job;
> > +	struct drm_sched_job *sched_job = NULL;
> >  	int r;
> >  
> >  	if (READ_ONCE(sched->pause_submit))
> >  		return;
> >  
> > -	entity = drm_sched_select_entity(sched);
> > +	/* Find entity with a ready job */
> > +	while (!sched_job && (entity = drm_sched_select_entity(sched))) {
> > +		sched_job = drm_sched_entity_pop_job(entity);
> > +		if (!sched_job)
> > +			complete_all(&entity->entity_idle);
> > +	}
> >  	if (!entity)
> > -		return;
> > -
> > -	sched_job = drm_sched_entity_pop_job(entity);
> > -	if (!sched_job) {
> > -		complete_all(&entity->entity_idle);
> >  		return;	/* No more work */
> > -	}
> >  
> >  	s_fence = sched_job->s_fence;
> >  
>