On 16/05/2025 11:54, Danilo Krummrich wrote:
On Fri, May 16, 2025 at 11:19:50AM +0100, Tvrtko Ursulin wrote:
On 16/05/2025 10:53, Danilo Krummrich wrote:
On Fri, May 16, 2025 at 10:33:30AM +0100, Tvrtko Ursulin wrote:
On 24/04/2025 10:55, Philipp Stanner wrote:
+ * @kill_fence_context: kill the fence context belonging to this
scheduler
Which fence context would that be? ;)
There's one one per ring and a scheduler instance represents a single ring. So,
what should be specified here?
I was pointing out the fact not all drivers are 1:1 sched:entity.
I'm well aware, but how is that relevant? Entities don't have an associated
fence context, but a GPU Ring (either hardware or software) has, which a
scheduler instance represents.
Aha! Well.. how it is relevant and do entities not have an associated
fence context? Well, entity->fence_context.. that was my first
association this whole time. Never it crossed my mind this is talking
about the hardware fence context. Proof in the pudding naming should be
improved.
But I also don't think there is a requirement for fences returned from
->run_job() to have a single context. Which again makes it not the best
naming.
Thought it would be obvious from the ";)".
I should read from ";)" that you refer to a 1:N-sched:entity relationship (which
doesn't seem to be related)?
Also, "fence context" would be a new terminology in gpu_scheduler.h API
level. You could call it ->sched_fini() or similar to signify at which point
in the API it gets called and then the fact it takes sched as parameter
would be natural.
The driver should tear down the fence context in this callback, not the while
scheduler. ->sched_fini() would hence be misleading.
Not the while what? Not while drm_sched_fini()?
*whole
Could call it sched_kill()
or anything. My point is that we dont' have "fence context" in the API but
entities so adding a new term sounds sub-optimal.
In the callback the driver should neither tear down an entity, nor the whole
scheduler, hence we shouldn't call it like that. sched_kill() is therefore
misleading as well.
->sched_exit()? ->sched_stop()? ->sched_cleanup()?
It should be named after what it actually does (or should do). Feel free to
propose a different name that conforms with that.
We also probably want some commentary on the topic of indefinite (or very
long at least) blocking a thread exit / SIGINT/TERM/KILL time.
You mean in case the driver does implement the callback, but does *not* properly
tear down the fence context? So, you ask for describing potential consequences
of drivers having bugs in the implementation of the callback? Or something else?
I was proposing the kerneldoc for the vfunc should document the callback
must not block, or if blocking is unavoidable, either document a guideline
on how long is acceptable. Maybe even enforce a limit in the scheduler core
itself.
Killing the fence context shouldn't block.
Cool. And maybe convert the wait_event to wait_event_timeout with a
warning to be robust.
Mind you, I still think a solution which does not add new state
machinery should be preferred.
Regards,
Tvrtko
