[PATCH 09/10] drm/amdgpu: add gang submit backend
Christian König
ckoenig.leichtzumerken at gmail.com
Sat Mar 5 18:40:41 UTC 2022
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.
If we don't check for NULL here we would just crash.
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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