On Thu, Aug 2, 2018, 8:09 PM Andrey Grodzovsky <andrey.grodzov...@amd.com>
wrote:
>
>
> On 08/02/2018 02:43 AM, Nayan Deshmukh wrote:
>
> Hi Andrey,
>
> Good catch. I guess since both Christian and I were working on it
> parallelly we didn't catch this problem.
>
> If it is only causing a problem in push_job then we can handle it
> something like this:
>
>
> ----------------------------------------------------------------------------------------------------------------------------
> diff --git a/drivers/gpu/drm/scheduler/gpu_scheduler.c
> b/drivers/gpu/drm/scheduler/gpu_scheduler.c
> index 05dc6ecd4003..f344ce32f128 100644
> --- a/drivers/gpu/drm/scheduler/gpu_scheduler.c
> +++ b/drivers/gpu/drm/scheduler/gpu_scheduler.c
> @@ -563,6 +563,11 @@ void drm_sched_entity_push_job(struct drm_sched_job
> *sched_job,
> first = spsc_queue_count(&entity->job_queue) == 0;
> reschedule = idle && first && (entity->num_rq_list > 1);
>
> + if (first && list_empty(&entity->list)) {
>
>
> first might be false if the other process interrupted by SIGKILL in
> middle of wait_event_killable in drm_sched_entity_flush when there were
> still item in queue.
> I don't see a good way besides adding a 'stopped' flag to
> drm_sched_enitity.
>
Sorry I missed this mail. This case might happen but this was also not
being handled previously.
Nayan
>
> Andrey
>
> + DRM_ERROR("Trying to push to a killed entity\n");
> + return;
> + }
> +
> if (reschedule) {
> rq = drm_sched_entity_get_free_sched(entity);
> spin_lock(&entity->rq_lock);
> @@ -580,11 +585,6 @@ void drm_sched_entity_push_job(struct drm_sched_job
> *sched_job,
> if (first) {
> /* Add the entity to the run queue */
> spin_lock(&entity->rq_lock);
> - if (!entity->rq) {
> - DRM_ERROR("Trying to push to a killed entity\n");
> - spin_unlock(&entity->rq_lock);
> - return;
> - }
> drm_sched_rq_add_entity(entity->rq, entity);
> spin_unlock(&entity->rq_lock);
> drm_sched_wakeup(entity->rq->sched);
>
> -----------------------------------------------------------------------------------------------------------------------------
>
>
> On Thu, Aug 2, 2018 at 3:55 AM Andrey Grodzovsky <
> andrey.grodzov...@amd.com> wrote:
>
>> Thinking again about this change and 53d5f1e drm/scheduler: move idle
>> entities to scheduler with less load v2
>>
>> Looks to me like use case for which fc9a539 drm/scheduler: add NULL
>> pointer check for run queue (v2) was done
>>
>> will not work anymore.
>>
>> First of all in drm_sched_entity_push_job, 'if (!entity->rq)' will never
>> be true any more since we stopped entity->rq to NULL in
>>
>> drm_sched_entity_flush.
>>
>> Second of all, even after we removed the entity from rq in
>> drm_sched_entity_flush to terminate any subsequent submissions
>>
>> to the queue the other thread doing push job can just acquire again a
>> run queue
>>
>> from drm_sched_entity_get_free_sched and continue submission so you
>> can't substitute ' if (!entity->rq)' to 'if (list_empty(&entity->list))'.
>>
>> What about adding a 'stopped' flag to drm_sched_entity to be set in
>> drm_sched_entity_flush and in
>>
>> But it might be worth adding a stopped flag field if it is required at
> other places as well.
>
> Thanks,
> Nayan
>
>> drm_sched_entity_push_job check for 'if (!entity->stopped)' instead of
>> ' if (!entity->rq)' ?
>>
>> Andrey
>>
>>
>> On 07/30/2018 07:03 AM, Christian König wrote:
>> > We removed the redundancy of having an extra scheduler field, so we
>> > can't set the rq to NULL any more or otherwise won't know which
>> > scheduler to use for the cleanup.
>> >
>> > Just remove the entity from the scheduling list instead.
>> >
>> > Signed-off-by: Christian König <christian.koe...@amd.com>
>> > ---
>> > drivers/gpu/drm/scheduler/gpu_scheduler.c | 35
>> +++++++------------------------
>> > 1 file changed, 8 insertions(+), 27 deletions(-)
>> >
>> > diff --git a/drivers/gpu/drm/scheduler/gpu_scheduler.c
>> b/drivers/gpu/drm/scheduler/gpu_scheduler.c
>> > index f563e4fbb4b6..1b733229201e 100644
>> > --- a/drivers/gpu/drm/scheduler/gpu_scheduler.c
>> > +++ b/drivers/gpu/drm/scheduler/gpu_scheduler.c
>> > @@ -198,21 +198,6 @@ int drm_sched_entity_init(struct drm_sched_entity
>> *entity,
>> > }
>> > EXPORT_SYMBOL(drm_sched_entity_init);
>> >
>> > -/**
>> > - * drm_sched_entity_is_initialized - Query if entity is initialized
>> > - *
>> > - * @sched: Pointer to scheduler instance
>> > - * @entity: The pointer to a valid scheduler entity
>> > - *
>> > - * return true if entity is initialized, false otherwise
>> > -*/
>> > -static bool drm_sched_entity_is_initialized(struct drm_gpu_scheduler
>> *sched,
>> > - struct drm_sched_entity
>> *entity)
>> > -{
>> > - return entity->rq != NULL &&
>> > - entity->rq->sched == sched;
>> > -}
>> > -
>> > /**
>> > * drm_sched_entity_is_idle - Check if entity is idle
>> > *
>> > @@ -224,7 +209,8 @@ static bool drm_sched_entity_is_idle(struct
>> drm_sched_entity *entity)
>> > {
>> > rmb();
>> >
>> > - if (!entity->rq || spsc_queue_peek(&entity->job_queue) == NULL)
>> > + if (list_empty(&entity->list) ||
>> > + spsc_queue_peek(&entity->job_queue) == NULL)
>> > return true;
>> >
>> > return false;
>> > @@ -279,8 +265,6 @@ long drm_sched_entity_flush(struct drm_sched_entity
>> *entity, long timeout)
>> > long ret = timeout;
>> >
>> > sched = entity->rq->sched;
>> > - if (!drm_sched_entity_is_initialized(sched, entity))
>> > - return ret;
>> > /**
>> > * The client will not queue more IBs during this fini, consume
>> existing
>> > * queued IBs or discard them on SIGKILL
>> > @@ -299,7 +283,7 @@ long drm_sched_entity_flush(struct drm_sched_entity
>> *entity, long timeout)
>> > last_user = cmpxchg(&entity->last_user, current->group_leader,
>> NULL);
>> > if ((!last_user || last_user == current->group_leader) &&
>> > (current->flags & PF_EXITING) && (current->exit_code ==
>> SIGKILL))
>> > - drm_sched_entity_set_rq(entity, NULL);
>> > + drm_sched_rq_remove_entity(entity->rq, entity);
>> >
>> > return ret;
>> > }
>> > @@ -320,7 +304,7 @@ void drm_sched_entity_fini(struct drm_sched_entity
>> *entity)
>> > struct drm_gpu_scheduler *sched;
>> >
>> > sched = entity->rq->sched;
>> > - drm_sched_entity_set_rq(entity, NULL);
>> > + drm_sched_rq_remove_entity(entity->rq, entity);
>> >
>> > /* Consumption of existing IBs wasn't completed. Forcefully
>> > * remove them here.
>> > @@ -416,15 +400,12 @@ void drm_sched_entity_set_rq(struct
>> drm_sched_entity *entity,
>> > if (entity->rq == rq)
>> > return;
>> >
>> > - spin_lock(&entity->rq_lock);
>> > -
>> > - if (entity->rq)
>> > - drm_sched_rq_remove_entity(entity->rq, entity);
>> > + BUG_ON(!rq);
>> >
>> > + spin_lock(&entity->rq_lock);
>> > + drm_sched_rq_remove_entity(entity->rq, entity);
>> > entity->rq = rq;
>> > - if (rq)
>> > - drm_sched_rq_add_entity(rq, entity);
>> > -
>> > + drm_sched_rq_add_entity(rq, entity);
>> > spin_unlock(&entity->rq_lock);
>> > }
>> > EXPORT_SYMBOL(drm_sched_entity_set_rq);
>>
>>
>
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