Inlined:
On 2022-07-14 06:39, 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@xxxxxxx>
> ---
> 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 2871a3e3801f..19308db52984 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> @@ -881,6 +881,7 @@ 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];
> @@ -1288,6 +1289,8 @@ u32 amdgpu_device_pcie_port_rreg(struct amdgpu_device *adev,
> u32 reg);
> void amdgpu_device_pcie_port_wreg(struct amdgpu_device *adev,
> u32 reg, u32 v);
> +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 e1c9587f659b..f80beb7208c0 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> @@ -3499,6 +3499,7 @@ 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;
> @@ -3979,6 +3980,7 @@ 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);
>
> @@ -5905,3 +5907,35 @@ void amdgpu_device_pcie_port_wreg(struct amdgpu_device *adev,
> (void)RREG32(data);
> spin_unlock_irqrestore(&adev->pcie_idx_lock, flags);
> }
> +
> +/**
> + * 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.
If you're redoing this patch (as it seems you would given Andrey's comment),
I'd drop mentioning the return result as it makes it a bit confusing being at the end
and referring to something mentioned earlier in the sentence. Perhaps just this
would suffice:
Try to switch to a new gang.
> + * Returns: Either NULL if we switched correctly or a reference to the existing
> + * gang.
Here you explain the return result, I'd drop the "Either" and say this:
Returns NULL if we switched to the new gang, or a reference to
the current gang.
No need for a semi-colon.
Regards,
Luben
> + */
> +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 3255b2fca611..f3a1fdbd41a3 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_job.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_job.c
> @@ -180,11 +180,29 @@ 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)
> @@ -258,12 +276,16 @@ 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);
> +
> 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;
> @@ -275,8 +297,10 @@ 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);
