[PATCH 5/5] drm/amdgpu: Follow up change to previous drm scheduler change.
Christian König
christian.koenig at amd.com
Thu Jun 23 05:52:11 UTC 2022
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.
>
> 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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