[PATCH v3 4/9] drm/scheduler: Add fence deadline support
Andrey Grodzovsky
andrey.grodzovsky at amd.com
Wed Sep 22 14:31:22 UTC 2021
On 2021-09-21 11:32 p.m., Rob Clark wrote:
> On Tue, Sep 21, 2021 at 7:18 PM Andrey Grodzovsky
> <andrey.grodzovsky at amd.com> wrote:
>>
>> On 2021-09-21 4:47 p.m., Rob Clark wrote:
>>> On Tue, Sep 21, 2021 at 1:09 PM Andrey Grodzovsky
>>> <andrey.grodzovsky at amd.com> wrote:
>>>> On 2021-09-03 2:47 p.m., Rob Clark wrote:
>>>>
>>>>> From: Rob Clark <robdclark at chromium.org>
>>>>>
>>>>> As the finished fence is the one that is exposed to userspace, and
>>>>> therefore the one that other operations, like atomic update, would
>>>>> block on, we need to propagate the deadline from from the finished
>>>>> fence to the actual hw fence.
>>>>>
>>>>> v2: Split into drm_sched_fence_set_parent() (ckoenig)
>>>>>
>>>>> Signed-off-by: Rob Clark <robdclark at chromium.org>
>>>>> ---
>>>>> drivers/gpu/drm/scheduler/sched_fence.c | 34 +++++++++++++++++++++++++
>>>>> drivers/gpu/drm/scheduler/sched_main.c | 2 +-
>>>>> include/drm/gpu_scheduler.h | 8 ++++++
>>>>> 3 files changed, 43 insertions(+), 1 deletion(-)
>>>>>
>>>>> diff --git a/drivers/gpu/drm/scheduler/sched_fence.c b/drivers/gpu/drm/scheduler/sched_fence.c
>>>>> index bcea035cf4c6..4fc41a71d1c7 100644
>>>>> --- a/drivers/gpu/drm/scheduler/sched_fence.c
>>>>> +++ b/drivers/gpu/drm/scheduler/sched_fence.c
>>>>> @@ -128,6 +128,30 @@ static void drm_sched_fence_release_finished(struct dma_fence *f)
>>>>> dma_fence_put(&fence->scheduled);
>>>>> }
>>>>>
>>>>> +static void drm_sched_fence_set_deadline_finished(struct dma_fence *f,
>>>>> + ktime_t deadline)
>>>>> +{
>>>>> + struct drm_sched_fence *fence = to_drm_sched_fence(f);
>>>>> + unsigned long flags;
>>>>> +
>>>>> + spin_lock_irqsave(&fence->lock, flags);
>>>>> +
>>>>> + /* If we already have an earlier deadline, keep it: */
>>>>> + if (test_bit(DMA_FENCE_FLAG_HAS_DEADLINE_BIT, &f->flags) &&
>>>>> + ktime_before(fence->deadline, deadline)) {
>>>>> + spin_unlock_irqrestore(&fence->lock, flags);
>>>>> + return;
>>>>> + }
>>>>> +
>>>>> + fence->deadline = deadline;
>>>>> + set_bit(DMA_FENCE_FLAG_HAS_DEADLINE_BIT, &f->flags);
>>>>> +
>>>>> + spin_unlock_irqrestore(&fence->lock, flags);
>>>>> +
>>>>> + if (fence->parent)
>>>>> + dma_fence_set_deadline(fence->parent, deadline);
>>>>> +}
>>>>> +
>>>>> static const struct dma_fence_ops drm_sched_fence_ops_scheduled = {
>>>>> .get_driver_name = drm_sched_fence_get_driver_name,
>>>>> .get_timeline_name = drm_sched_fence_get_timeline_name,
>>>>> @@ -138,6 +162,7 @@ static const struct dma_fence_ops drm_sched_fence_ops_finished = {
>>>>> .get_driver_name = drm_sched_fence_get_driver_name,
>>>>> .get_timeline_name = drm_sched_fence_get_timeline_name,
>>>>> .release = drm_sched_fence_release_finished,
>>>>> + .set_deadline = drm_sched_fence_set_deadline_finished,
>>>>> };
>>>>>
>>>>> struct drm_sched_fence *to_drm_sched_fence(struct dma_fence *f)
>>>>> @@ -152,6 +177,15 @@ struct drm_sched_fence *to_drm_sched_fence(struct dma_fence *f)
>>>>> }
>>>>> EXPORT_SYMBOL(to_drm_sched_fence);
>>>>>
>>>>> +void drm_sched_fence_set_parent(struct drm_sched_fence *s_fence,
>>>>> + struct dma_fence *fence)
>>>>> +{
>>>>> + s_fence->parent = dma_fence_get(fence);
>>>>> + if (test_bit(DMA_FENCE_FLAG_HAS_DEADLINE_BIT,
>>>>> + &s_fence->finished.flags))
>>>>> + dma_fence_set_deadline(fence, s_fence->deadline);
>>>> I believe above you should pass be s_fence->finished to
>>>> dma_fence_set_deadline
>>>> instead it fence which is the HW fence itself.
>>> Hmm, unless this has changed recently with some patches I don't have,
>>> s_fence->parent is the one signalled by hw, so it is the one we want
>>> to set the deadline on
>>>
>>> BR,
>>> -R
>>
>> No it didn't change. But then when exactly will
>> drm_sched_fence_set_deadline_finished
>> execute such that fence->parent != NULL ? In other words, I am not clear
>> how propagation
>> happens otherwise - if dma_fence_set_deadline is called with the HW
>> fence then the assumption
>> here is that driver provided driver specific
>> dma_fence_ops.dma_fence_set_deadline callback executes
>> but I was under impression that drm_sched_fence_set_deadline_finished is
>> the one that propagates
>> the deadline to the HW fence's callback and for it to execute
>> dma_fence_set_deadline needs to be called
>> with s_fence->finished.
> Assuming I didn't screw up drm/msm conversion to scheduler,
> &s_fence->finished is the one that will be returned to userspace.. and
> later passed back to kernel for atomic commit (or to the compositor).
> So it is the one that fence->set_deadline() will be called on. But
> s_fence->parent is the actual hw fence that needs to know about the
> deadline. Depending on whether or not the job has been written into
> hw ringbuffer or not, there are two cases:
>
> 1) not scheduled yet, s_fence will store the deadline and propagate it
> later once s_fence->parent is known
And by later you mean the call to drm_sched_fence_set_parent
after HW fence is returned ? If yes I think i get it now.
Andrey
> 2) already scheduled, in which case s_fence->finished.set_deadline
> will propagate it directly to the real fence
>
> BR,
> -R
>
>> Andrey
>>
>>
>>
>>>> Andrey
>>>>
>>>>
>>>>> +}
>>>>> +
>>>>> struct drm_sched_fence *drm_sched_fence_alloc(struct drm_sched_entity *entity,
>>>>> void *owner)
>>>>> {
>>>>> diff --git a/drivers/gpu/drm/scheduler/sched_main.c b/drivers/gpu/drm/scheduler/sched_main.c
>>>>> index 595e47ff7d06..27bf0ac0625f 100644
>>>>> --- a/drivers/gpu/drm/scheduler/sched_main.c
>>>>> +++ b/drivers/gpu/drm/scheduler/sched_main.c
>>>>> @@ -978,7 +978,7 @@ static int drm_sched_main(void *param)
>>>>> drm_sched_fence_scheduled(s_fence);
>>>>>
>>>>> if (!IS_ERR_OR_NULL(fence)) {
>>>>> - s_fence->parent = dma_fence_get(fence);
>>>>> + drm_sched_fence_set_parent(s_fence, fence);
>>>>> r = dma_fence_add_callback(fence, &sched_job->cb,
>>>>> drm_sched_job_done_cb);
>>>>> if (r == -ENOENT)
>>>>> diff --git a/include/drm/gpu_scheduler.h b/include/drm/gpu_scheduler.h
>>>>> index 7f77a455722c..158ddd662469 100644
>>>>> --- a/include/drm/gpu_scheduler.h
>>>>> +++ b/include/drm/gpu_scheduler.h
>>>>> @@ -238,6 +238,12 @@ struct drm_sched_fence {
>>>>> */
>>>>> struct dma_fence finished;
>>>>>
>>>>> + /**
>>>>> + * @deadline: deadline set on &drm_sched_fence.finished which
>>>>> + * potentially needs to be propagated to &drm_sched_fence.parent
>>>>> + */
>>>>> + ktime_t deadline;
>>>>> +
>>>>> /**
>>>>> * @parent: the fence returned by &drm_sched_backend_ops.run_job
>>>>> * when scheduling the job on hardware. We signal the
>>>>> @@ -505,6 +511,8 @@ void drm_sched_entity_set_priority(struct drm_sched_entity *entity,
>>>>> enum drm_sched_priority priority);
>>>>> bool drm_sched_entity_is_ready(struct drm_sched_entity *entity);
>>>>>
>>>>> +void drm_sched_fence_set_parent(struct drm_sched_fence *s_fence,
>>>>> + struct dma_fence *fence);
>>>>> struct drm_sched_fence *drm_sched_fence_alloc(
>>>>> struct drm_sched_entity *s_entity, void *owner);
>>>>> void drm_sched_fence_init(struct drm_sched_fence *fence,
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