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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.
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);
-----------------------------------------------------------------------------------------------------------------------------
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.koenig@xxxxxxx>
> ---
> 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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