[PATCH 09/10] drm/amdgpu: add gang submit backend
Andrey Grodzovsky
andrey.grodzovsky at amd.com
Mon Mar 7 15:40:41 UTC 2022
On 2022-03-05 13:40, Christian König wrote:
> Am 04.03.22 um 18:10 schrieb Andrey Grodzovsky:
>>
>> On 2022-03-03 03:23, Christian König wrote:
>>> Allows submitting jobs as gang which needs to run on multiple
>>> engines at the same time.
>>>
>>> Basic idea is that we have a global gang submit fence representing
>>> when the
>>> gang leader is finally pushed to run on the hardware last.
>>>
>>> Jobs submitted as gang are never re-submitted in case of a GPU reset
>>> since this
>>> won't work and will just deadlock the hardware immediately again.
>>>
>>> Signed-off-by: Christian König <christian.koenig at amd.com>
>>> ---
>>> drivers/gpu/drm/amd/amdgpu/amdgpu.h | 3 ++
>>> drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 34
>>> ++++++++++++++++++++++
>>> drivers/gpu/drm/amd/amdgpu/amdgpu_job.c | 28 ++++++++++++++++--
>>> drivers/gpu/drm/amd/amdgpu/amdgpu_job.h | 3 ++
>>> 4 files changed, 66 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
>>> index 7f447ed7a67f..a664d43d7502 100644
>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
>>> @@ -852,6 +852,7 @@ struct amdgpu_device {
>>> u64 fence_context;
>>> unsigned num_rings;
>>> struct amdgpu_ring *rings[AMDGPU_MAX_RINGS];
>>> + struct dma_fence __rcu *gang_submit;
>>> bool ib_pool_ready;
>>> struct amdgpu_sa_manager ib_pools[AMDGPU_IB_POOL_MAX];
>>> struct amdgpu_sched
>>> gpu_sched[AMDGPU_HW_IP_NUM][AMDGPU_RING_PRIO_MAX];
>>> @@ -1233,6 +1234,8 @@ void amdgpu_device_invalidate_hdp(struct
>>> amdgpu_device *adev,
>>> struct amdgpu_ring *ring);
>>> void amdgpu_device_halt(struct amdgpu_device *adev);
>>> +struct dma_fence *amdgpu_device_switch_gang(struct amdgpu_device
>>> *adev,
>>> + struct dma_fence *gang);
>>> /* atpx handler */
>>> #if defined(CONFIG_VGA_SWITCHEROO)
>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
>>> index d78141e2c509..a116b8c08827 100644
>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
>>> @@ -3512,6 +3512,7 @@ int amdgpu_device_init(struct amdgpu_device
>>> *adev,
>>> adev->gmc.gart_size = 512 * 1024 * 1024;
>>> adev->accel_working = false;
>>> adev->num_rings = 0;
>>> + RCU_INIT_POINTER(adev->gang_submit, dma_fence_get_stub());
>>> adev->mman.buffer_funcs = NULL;
>>> adev->mman.buffer_funcs_ring = NULL;
>>> adev->vm_manager.vm_pte_funcs = NULL;
>>> @@ -3989,6 +3990,7 @@ void amdgpu_device_fini_sw(struct
>>> amdgpu_device *adev)
>>> release_firmware(adev->firmware.gpu_info_fw);
>>> adev->firmware.gpu_info_fw = NULL;
>>> adev->accel_working = false;
>>> + dma_fence_put(rcu_dereference_protected(adev->gang_submit, true));
>>> amdgpu_reset_fini(adev);
>>> @@ -5744,3 +5746,35 @@ void amdgpu_device_halt(struct
>>> amdgpu_device *adev)
>>> pci_disable_device(pdev);
>>> pci_wait_for_pending_transaction(pdev);
>>> }
>>> +
>>> +/**
>>> + * amdgpu_device_switch_gang - switch to a new gang
>>> + * @adev: amdgpu_device pointer
>>> + * @gang: the gang to switch to
>>> + *
>>> + * Try to switch to a new gang or return a reference to the current
>>> gang if that
>>> + * isn't possible.
>>> + * Returns: Either NULL if we switched correctly or a reference to
>>> the existing
>>> + * gang.
>>> + */
>>> +struct dma_fence *amdgpu_device_switch_gang(struct amdgpu_device
>>> *adev,
>>> + struct dma_fence *gang)
>>> +{
>>> + struct dma_fence *old = NULL;
>>> +
>>> + do {
>>> + dma_fence_put(old);
>>> + old = dma_fence_get_rcu_safe(&adev->gang_submit);
>>> +
>>> + if (old == gang)
>>> + break;
>>> +
>>> + if (!dma_fence_is_signaled(old))
>>> + return old;
>>> +
>>> + } while (cmpxchg((struct dma_fence __force **)&adev->gang_submit,
>>> + old, gang) != old);
>>> +
>>> + dma_fence_put(old);
>>> + return NULL;
>>> +}
>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_job.c
>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_job.c
>>> index e07ceae36a5c..059e11c7898c 100644
>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_job.c
>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_job.c
>>> @@ -169,11 +169,29 @@ static void amdgpu_job_free_cb(struct
>>> drm_sched_job *s_job)
>>> kfree(job);
>>> }
>>> +void amdgpu_job_set_gang_leader(struct amdgpu_job *job,
>>> + struct amdgpu_job *leader)
>>> +{
>>> + struct dma_fence *fence = &leader->base.s_fence->scheduled;
>>> +
>>> + WARN_ON(job->gang_submit);
>>> +
>>> + /*
>>> + * Don't add a reference when we are the gang leader to avoid
>>> circle
>>> + * dependency.
>>> + */
>>> + if (job != leader)
>>> + dma_fence_get(fence);
>>> + job->gang_submit = fence;
>>> +}
>>> +
>>> void amdgpu_job_free(struct amdgpu_job *job)
>>> {
>>> amdgpu_job_free_resources(job);
>>> amdgpu_sync_free(&job->sync);
>>> amdgpu_sync_free(&job->sched_sync);
>>> + if (job->gang_submit != &job->base.s_fence->scheduled)
>>> + dma_fence_put(job->gang_submit);
>>> /* only put the hw fence if has embedded fence */
>>> if (job->hw_fence.ops != NULL)
>>> @@ -247,12 +265,16 @@ static struct dma_fence
>>> *amdgpu_job_dependency(struct drm_sched_job *sched_job,
>>> fence = amdgpu_sync_get_fence(&job->sync);
>>> }
>>> + if (!fence && !job->gang_submit)
>>> + fence = amdgpu_device_switch_gang(ring->adev,
>>> job->gang_submit);
>>> +
>>
>>
>> Why job->gang_submit should be NULL in the check above ? Don't you
>> want to switch to an actual new gang fence here ?
>> Jobs that don't have gang_submit fence set are not gang jobs anyway
>> and we don't care for this dependency
>> for them right ?
>
> Well exactly that's the point. That a job is not part of a gang submit
> is signaled by setting the pointer to NULL.
No dispute on this
>
> If we don't check for NULL here we would just crash.
But you go into the 'if clause' if job->gang_submit is equal to NULL, i
would expect to see here
if (!fence &&*job->gang_submit*) because you want to switch to an actual
new gang (not to NULL)
Andrey
>
> Christian.
>
>>
>> Andrey
>>
>>
>>> return fence;
>>> }
>>> static struct dma_fence *amdgpu_job_run(struct drm_sched_job
>>> *sched_job)
>>> {
>>> struct amdgpu_ring *ring = to_amdgpu_ring(sched_job->sched);
>>> + struct amdgpu_device *adev = ring->adev;
>>> struct dma_fence *fence = NULL, *finished;
>>> struct amdgpu_job *job;
>>> int r = 0;
>>> @@ -264,8 +286,10 @@ static struct dma_fence *amdgpu_job_run(struct
>>> drm_sched_job *sched_job)
>>> trace_amdgpu_sched_run_job(job);
>>> - if (job->vram_lost_counter !=
>>> atomic_read(&ring->adev->vram_lost_counter))
>>> - dma_fence_set_error(finished, -ECANCELED);/* skip IB as
>>> well if VRAM lost */
>>> + /* Skip job if VRAM is lost and never resubmit gangs */
>>> + if (job->vram_lost_counter !=
>>> atomic_read(&adev->vram_lost_counter) ||
>>> + (job->job_run_counter && job->gang_submit))
>>> + dma_fence_set_error(finished, -ECANCELED);
>>> if (finished->error < 0) {
>>> DRM_INFO("Skip scheduling IBs!\n");
>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_job.h
>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_job.h
>>> index 0bab8fe0d419..615328130615 100644
>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_job.h
>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_job.h
>>> @@ -51,6 +51,7 @@ struct amdgpu_job {
>>> struct amdgpu_sync sched_sync;
>>> struct dma_fence hw_fence;
>>> struct dma_fence *external_hw_fence;
>>> + struct dma_fence *gang_submit;
>>> uint32_t preamble_status;
>>> uint32_t preemption_status;
>>> bool vm_needs_flush;
>>> @@ -80,6 +81,8 @@ int amdgpu_job_alloc_with_ib(struct amdgpu_device
>>> *adev, unsigned size,
>>> void amdgpu_job_set_resources(struct amdgpu_job *job, struct
>>> amdgpu_bo *gds,
>>> struct amdgpu_bo *gws, struct amdgpu_bo *oa);
>>> void amdgpu_job_free_resources(struct amdgpu_job *job);
>>> +void amdgpu_job_set_gang_leader(struct amdgpu_job *job,
>>> + struct amdgpu_job *leader);
>>> void amdgpu_job_free(struct amdgpu_job *job);
>>> int amdgpu_job_submit(struct amdgpu_job *job, struct
>>> drm_sched_entity *entity,
>>> void *owner, struct dma_fence **f);
>
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