On 12/05/2025 09:00, Philipp Stanner wrote:
On Thu, 2025-05-08 at 13:51 +0100, Tvrtko Ursulin wrote:
Hi Philipp,
On 08/05/2025 12:03, Philipp Stanner wrote:
On Thu, 2025-04-24 at 11:55 +0200, Philipp Stanner wrote:
The unit tests so far took care manually of avoiding memory leaks
that
might have occurred when calling drm_sched_fini().
The scheduler now takes care by itself of avoiding memory leaks
if
the
driver provides the callback
drm_sched_backend_ops.kill_fence_context().
Implement that callback for the unit tests. Remove the manual
cleanup
code.
@Tvrtko: On a scale from 1-10, how much do you love this patch? :)
Specific patch aside, it is the series as a whole I would like to be
sure there isn't a more elegant way to achieve the same end result.
I count this as a 9/10 \o/
:) Yes, sorry, it would a bit lower than that, at least until someone
can point out a fatal flaw in my alternative. :)
But jokes aside:
Like that sketch of a counter proposal I sent for the reasons listed
with it. Which were, AFAIR, to avoid needing to add more state
machine,
Well the state machine added is basically just the waitqueue. The
WRITE_ONCE booleans are currently just for correctness and clarity.
I've looked at them and want to remove them all in an other patch,
because I think they're not needed (workqueue handles that)
But yes, the added state is > 0
to avoid mandating drivers have to keep an internal list,
That's not mandated by the scheduler, but by logic itself. All drivers
need to have a list of on-flight fences. Otherwise the drivers would
have no chance of signaling those fences once their GPU tells them to
do so.
Probably it would be hard to signal without tracking of some sort yes,
although it wouldn't have to be indexed by fence context, or looked up
by it so maybe still simpler.
More importantly I think with this comment I was thinking about the fact
that with ops->cancel_job() approach I was able to remove the _done_
list tracking from the mock scheduler.
I have now provided two users of the new API, nouveau and the unit
tests. Can you think of a party for which the suggested approach
wouldn't work?
I did not think along those lines yet so don't know. I just thought it
was too much code to implement a relatively simple thing and that also a
few things in the design bothered me.
If you look at the diffstat from my proposal and ignore kerneldoc and
unit test stats, it literally adds 8 lines to drm_sched_fini() and a
single line to gpu_scheduler.h:
+ void (*cancel_job)(struct drm_sched_job *sched_job);
And in the former after it stops the workers:
+ if (sched->ops->cancel_job) {
+ struct drm_sched_job *job;
+
+ list_for_each_entry_reverse(job, &sched->pending_list,
list) {
+ sched->ops->cancel_job(job);
+ sched->ops->free_job(job);
+ }
+ }
To me this looks quite clean. Unless, I say this again, I am missing
some fatal flaw why it doesn't work.
Don't get me wrong, your approach does work and it definitely has its
charm. However, I think what I propose here is syntactically a bit
cleaner because the classical order of a fence first being signaled in
the driver and then the associated job being freed as usual by the
scheduler is guaranteed. IOW, we primarily rely on the signaling path.
Either way, neither your nor my approach would have worked out of the
box in Nouveau without that driver exploding.
What do you mean by this - the latest version of your series does or
does not work for nouveau?
Regards,
Tvrtko
and to align
better with the existing prototypes in the sched ops table (where
everything operates on jobs).
That's not a hard criteria IMO. Those are sched_backend_ops, not
sched_job_backend_ops, and prepare_job() already takes a parameter
other than a job.
Cheers,
P.
Regards,
Tvrtko
Signed-off-by: Philipp Stanner <pha...@kernel.org>
---
.../gpu/drm/scheduler/tests/mock_scheduler.c | 34
++++++++++++-----
--
1 file changed, 21 insertions(+), 13 deletions(-)
diff --git a/drivers/gpu/drm/scheduler/tests/mock_scheduler.c
b/drivers/gpu/drm/scheduler/tests/mock_scheduler.c
index f999c8859cf7..a72d26ca8262 100644
--- a/drivers/gpu/drm/scheduler/tests/mock_scheduler.c
+++ b/drivers/gpu/drm/scheduler/tests/mock_scheduler.c
@@ -228,10 +228,30 @@ static void mock_sched_free_job(struct
drm_sched_job *sched_job)
/* Mock job itself is freed by the kunit framework. */
}
+static void mock_sched_fence_context_kill(struct
drm_gpu_scheduler
*gpu_sched)
+{
+ struct drm_mock_scheduler *sched =
drm_sched_to_mock_sched(gpu_sched);
+ struct drm_mock_sched_job *job;
+ unsigned long flags;
+
+ spin_lock_irqsave(&sched->lock, flags);
+ list_for_each_entry(job, &sched->job_list, link) {
+ spin_lock(&job->lock);
+ if (!dma_fence_is_signaled_locked(&job-
hw_fence)) {
+ dma_fence_set_error(&job->hw_fence, -
ECANCELED);
+ dma_fence_signal_locked(&job->hw_fence);
+ }
+ complete(&job->done);
+ spin_unlock(&job->lock);
+ }
+ spin_unlock_irqrestore(&sched->lock, flags);
+}
+
static const struct drm_sched_backend_ops
drm_mock_scheduler_ops = {
.run_job = mock_sched_run_job,
.timedout_job = mock_sched_timedout_job,
- .free_job = mock_sched_free_job
+ .free_job = mock_sched_free_job,
+ .kill_fence_context = mock_sched_fence_context_kill,
};
/**
@@ -300,18 +320,6 @@ void drm_mock_sched_fini(struct
drm_mock_scheduler *sched)
drm_mock_sched_job_complete(job);
spin_unlock_irqrestore(&sched->lock, flags);
- /*
- * Free completed jobs and jobs not yet processed by the
DRM
scheduler
- * free worker.
- */
- spin_lock_irqsave(&sched->lock, flags);
- list_for_each_entry_safe(job, next, &sched->done_list,
link)
- list_move_tail(&job->link, &list);
- spin_unlock_irqrestore(&sched->lock, flags);
-
- list_for_each_entry_safe(job, next, &list, link)
- mock_sched_free_job(&job->base);
-
drm_sched_fini(&sched->base);
}
