[PATCH 5/5] drm/amdgpu: Follow up change to previous drm scheduler change.
Andrey Grodzovsky
andrey.grodzovsky at amd.com
Thu Jun 23 14:51:28 UTC 2022
On 2022-06-23 01:52, Christian König wrote:
> Am 22.06.22 um 19:19 schrieb Andrey Grodzovsky:
>>
>> On 2022-06-22 03:17, Christian König wrote:
>>> Am 21.06.22 um 22:00 schrieb Andrey Grodzovsky:
>>>>
>>>> On 2022-06-21 03:28, Christian König wrote:
>>>>> Am 21.06.22 um 00:03 schrieb Andrey Grodzovsky:
>>>>>> Align refcount behaviour for amdgpu_job embedded HW fence with
>>>>>> classic pointer style HW fences by increasing refcount each
>>>>>> time emit is called so amdgpu code doesn't need to make workarounds
>>>>>> using amdgpu_job.job_run_counter to keep the HW fence refcount
>>>>>> balanced.
>>>>>
>>>>> Could we now also remove job_run_counter?
>>>>>
>>>>> Christian.
>>>>
>>>>
>>>> I am afraid not, job counter is needed since at all times the
>>>> refcount on the
>>>> embedded fence cannot drop to zero because this will free the job
>>>> itself before
>>>> the end of it's life cycle. We have to be able to differentiate in
>>>> amdgpu_fence_emit
>>>> between first ever call where we init the embedded fence's refcount
>>>> from scratch using kref_init
>>>> to repeating calls when refcount already > 0 and we just fake
>>>> increase the refcount to align
>>>> behavior with pointer style fences in other drivers.
>>>
>>> Well what we should probably rather do is move the init out of emit
>>> instead.
>>>
>>> The only down side I can see is that the sequence number isn't know
>>> on initial init and so needs to be zero or something like that.
>>>
>>> Regards,
>>> Christian.
>>
>>
>> Not sure how this help, the problem is not there but in
>> amdgpu_job_run, for embedded fence and resubmit job in pending list
>> amdgpu_job_run
>> will be called twice or even 3 times with recheck guilty job
>> sequence. I am supposed to do dma_fence_init to embeded HW fence only
>> on first call while on second and
>> third only update sequence_num and increase refcount. How can i
>> differentiate between first and non first calls without
>> job_run_counter ?
>
> Yeah, good point. We should really stop re-submitting jobs altogether
> in the kernel and move that whole functionality into userspace.
>
> Christian.
So i guess we keep this for now and see how to move resubmit
functionality to user space ? as a separate task ?
Andrey
>
>>
>> Andrey
>>
>>
>>>
>>>>
>>>> I guess we could assume that embedded fence is all zeroes before
>>>> first dma_fence_init if assuming the job itself
>>>> was allocated using kzalloc and so u can look at dma_fence_ops ==
>>>> NULL or maybe seqno == 0
>>>> as a hint if that the fist call or not but it's a risky assumption
>>>> in my opinion.
>>>>
>>>> Andrey
>>>>
>>>>
>>>>>
>>>>>>
>>>>>> Also since in the previous patch we resumed setting
>>>>>> s_fence->parent to NULL
>>>>>> in drm_sched_stop switch to directly checking if job->hw_fence is
>>>>>> signaled to short circuit reset if already signed.
>>>>>>
>>>>>> Signed-off-by: Andrey Grodzovsky <andrey.grodzovsky at amd.com>
>>>>>> Tested-by: Yiqing Yao <yiqing.yao at amd.com>
>>>>>> ---
>>>>>> drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c | 2 ++
>>>>>> drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 23
>>>>>> ++++++++++++++++------
>>>>>> drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c | 7 ++++++-
>>>>>> drivers/gpu/drm/amd/amdgpu/amdgpu_job.c | 4 ----
>>>>>> 4 files changed, 25 insertions(+), 11 deletions(-)
>>>>>>
>>>>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c
>>>>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c
>>>>>> index 513c57f839d8..447bd92c4856 100644
>>>>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c
>>>>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c
>>>>>> @@ -684,6 +684,8 @@ int amdgpu_amdkfd_submit_ib(struct
>>>>>> amdgpu_device *adev,
>>>>>> goto err_ib_sched;
>>>>>> }
>>>>>> + /* Drop the initial kref_init count (see drm_sched_main as
>>>>>> example) */
>>>>>> + dma_fence_put(f);
>>>>>> ret = dma_fence_wait(f, false);
>>>>>> err_ib_sched:
>>>>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
>>>>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
>>>>>> index c99541685804..f9718119834f 100644
>>>>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
>>>>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
>>>>>> @@ -5009,16 +5009,28 @@ static void
>>>>>> amdgpu_device_recheck_guilty_jobs(
>>>>>> /* clear job's guilty and depend the folowing step to
>>>>>> decide the real one */
>>>>>> drm_sched_reset_karma(s_job);
>>>>>> - /* for the real bad job, it will be resubmitted twice,
>>>>>> adding a dma_fence_get
>>>>>> - * to make sure fence is balanced */
>>>>>> - dma_fence_get(s_job->s_fence->parent);
>>>>>> drm_sched_resubmit_jobs_ext(&ring->sched, 1);
>>>>>> + if (!s_job->s_fence->parent) {
>>>>>> + DRM_WARN("Failed to get a HW fence for job!");
>>>>>> + continue;
>>>>>> + }
>>>>>> +
>>>>>> ret = dma_fence_wait_timeout(s_job->s_fence->parent,
>>>>>> false, ring->sched.timeout);
>>>>>> if (ret == 0) { /* timeout */
>>>>>> DRM_ERROR("Found the real bad job! ring:%s,
>>>>>> job_id:%llx\n",
>>>>>> ring->sched.name, s_job->id);
>>>>>> +
>>>>>> + /* Clear this failed job from fence array */
>>>>>> + amdgpu_fence_driver_clear_job_fences(ring);
>>>>>> +
>>>>>> + /* Since the job won't signal and we go for
>>>>>> + * another resubmit drop this parent pointer
>>>>>> + */
>>>>>> + dma_fence_put(s_job->s_fence->parent);
>>>>>> + s_job->s_fence->parent = NULL;
>>>>>> +
>>>>>> /* set guilty */
>>>>>> drm_sched_increase_karma(s_job);
>>>>>> retry:
>>>>>> @@ -5047,7 +5059,6 @@ static void amdgpu_device_recheck_guilty_jobs(
>>>>>> /* got the hw fence, signal finished fence */
>>>>>> atomic_dec(ring->sched.score);
>>>>>> - dma_fence_put(s_job->s_fence->parent);
>>>>>> dma_fence_get(&s_job->s_fence->finished);
>>>>>> dma_fence_signal(&s_job->s_fence->finished);
>>>>>> dma_fence_put(&s_job->s_fence->finished);
>>>>>> @@ -5220,8 +5231,8 @@ int amdgpu_device_gpu_recover(struct
>>>>>> amdgpu_device *adev,
>>>>>> *
>>>>>> * job->base holds a reference to parent fence
>>>>>> */
>>>>>> - if (job && job->base.s_fence->parent &&
>>>>>> - dma_fence_is_signaled(job->base.s_fence->parent)) {
>>>>>> + if (job && (job->hw_fence.ops != NULL) &&
>>>>>> + dma_fence_is_signaled(&job->hw_fence)) {
>>>>>> job_signaled = true;
>>>>>> dev_info(adev->dev, "Guilty job already signaled,
>>>>>> skipping HW reset");
>>>>>> goto skip_hw_reset;
>>>>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c
>>>>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c
>>>>>> index d6d54ba4c185..9bd4e18212fc 100644
>>>>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c
>>>>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c
>>>>>> @@ -164,11 +164,16 @@ int amdgpu_fence_emit(struct amdgpu_ring
>>>>>> *ring, struct dma_fence **f, struct amd
>>>>>> if (job && job->job_run_counter) {
>>>>>> /* reinit seq for resubmitted jobs */
>>>>>> fence->seqno = seq;
>>>>>> + /* TO be inline with external fence creation and other
>>>>>> drivers */
>>>>>> + dma_fence_get(fence);
>>>>>> } else {
>>>>>> - if (job)
>>>>>> + if (job) {
>>>>>> dma_fence_init(fence, &amdgpu_job_fence_ops,
>>>>>> &ring->fence_drv.lock,
>>>>>> adev->fence_context + ring->idx, seq);
>>>>>> + /* Against remove in amdgpu_job_{free, free_cb} */
>>>>>> + dma_fence_get(fence);
>>>>>> + }
>>>>>> else
>>>>>> dma_fence_init(fence, &amdgpu_fence_ops,
>>>>>> &ring->fence_drv.lock,
>>>>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_job.c
>>>>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_job.c
>>>>>> index 58568fdde2d0..638e1d600258 100644
>>>>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_job.c
>>>>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_job.c
>>>>>> @@ -267,10 +267,6 @@ static struct dma_fence
>>>>>> *amdgpu_job_run(struct drm_sched_job *sched_job)
>>>>>> DRM_ERROR("Error scheduling IBs (%d)\n", r);
>>>>>> }
>>>>>> - if (!job->job_run_counter)
>>>>>> - dma_fence_get(fence);
>>>>>> - else if (finished->error < 0)
>>>>>> - dma_fence_put(&job->hw_fence);
>>>>>> job->job_run_counter++;
>>>>>> amdgpu_job_free_resources(job);
>>>>>
>>>
>
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