[PATCH v2 2/2] drm/amdgpu: report the number of bytes moved at buffer creation

[Nicolai Hähnle]

On 09.02.2017 11:33, Samuel Pitoiset wrote:
> Like ttm_bo_validate(), ttm_bo_init() might need to move BO and
> the number of bytes moved by TTM should be reported. This can help
> the throttle buffer migration mechanism to make a better decision.

Hmm, this could double-count bytes if there's a concurrent CS submission 
going on.

It's only a heuristic, so I guess it's not too bad, but still - having 
at least a comment about this would be nice.

Nicolai

> v2: fix computation
>
> Signed-off-by: Samuel Pitoiset <samuel.pitoiset at gmail.com>
> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu.h        | 1 +
>  drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c     | 3 +--
>  drivers/gpu/drm/amd/amdgpu/amdgpu_object.c | 6 ++++++
>  3 files changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> index 402a8954c6d8..5227e4d1d5db 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> @@ -1720,6 +1720,7 @@ int amdgpu_cs_parser_init(struct amdgpu_cs_parser *p, void *data);
>  int amdgpu_cs_get_ring(struct amdgpu_device *adev, u32 ip_type,
>  		       u32 ip_instance, u32 ring,
>  		       struct amdgpu_ring **out_ring);
> +void amdgpu_cs_report_moved_bytes(struct amdgpu_device *adev, u64 num_bytes);
>  void amdgpu_ttm_placement_from_domain(struct amdgpu_bo *abo, u32 domain);
>  bool amdgpu_ttm_bo_is_amdgpu_bo(struct ttm_buffer_object *bo);
>  int amdgpu_ttm_tt_get_user_pages(struct ttm_tt *ttm, struct page **pages);
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
> index 6e948e4986ec..dade2fa9593a 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
> @@ -351,8 +351,7 @@ static u64 amdgpu_cs_get_threshold_for_moves(struct amdgpu_device *adev)
>   * submission. This can result in a debt that can stop buffer migrations
>   * temporarily.
>   */
> -static void amdgpu_cs_report_moved_bytes(struct amdgpu_device *adev,
> -					 u64 num_bytes)
> +void amdgpu_cs_report_moved_bytes(struct amdgpu_device *adev, u64 num_bytes)
>  {
>  	spin_lock(&adev->mm_stats.lock);
>  	adev->mm_stats.accum_us -= bytes_to_us(adev, num_bytes);
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
> index 556236a112c1..4aa2c8a94347 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
> @@ -323,6 +323,7 @@ int amdgpu_bo_create_restricted(struct amdgpu_device *adev,
>  	struct amdgpu_bo *bo;
>  	enum ttm_bo_type type;
>  	unsigned long page_align;
> +	u64 initial_bytes_moved;
>  	size_t acc_size;
>  	int r;
>
> @@ -399,10 +400,15 @@ int amdgpu_bo_create_restricted(struct amdgpu_device *adev,
>  		locked = ww_mutex_trylock(&bo->tbo.ttm_resv.lock);
>  		WARN_ON(!locked);
>  	}
> +
> +	initial_bytes_moved = atomic64_read(&adev->num_bytes_moved);
>  	r = ttm_bo_init(&adev->mman.bdev, &bo->tbo, size, type,
>  			&bo->placement, page_align, !kernel, NULL,
>  			acc_size, sg, resv ? resv : &bo->tbo.ttm_resv,
>  			&amdgpu_ttm_bo_destroy);
> +	amdgpu_cs_report_moved_bytes(adev,
> +		atomic64_read(&adev->num_bytes_moved) - initial_bytes_moved);
> +
>  	if (unlikely(r != 0)) {
>  		if (!resv)
>  			ww_mutex_unlock(&bo->tbo.resv->lock);
>