linux-kernel - Re: [PATCH v2 13/20] drm/amdgpu: use multiple entities in amdgpu_move

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Message-ID: <2ee1929f-4518-434a-b388-7eadee10d40f@amd.com>
Date: Mon, 17 Nov 2025 10:12:44 +0100
From: Christian König <christian.koenig@....com>
To: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@....com>,
 Alex Deucher <alexander.deucher@....com>, David Airlie <airlied@...il.com>,
 Simona Vetter <simona@...ll.ch>
Cc: amd-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 13/20] drm/amdgpu: use multiple entities in
 amdgpu_move_blit

On 11/13/25 17:05, Pierre-Eric Pelloux-Prayer wrote:
> Thanks to "drm/ttm: rework pipelined eviction fence handling", ttm
> can deal correctly with moves and evictions being executed from
> different contexts.
> 
> Create several entities and use them in a round-robin fashion.
> 
> Signed-off-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@....com>
> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 13 ++++++++++---
>  drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h |  1 +
>  2 files changed, 11 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> index 486c701d0d5b..6c333dba7a35 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> @@ -401,6 +401,7 @@ static int amdgpu_move_blit(struct ttm_buffer_object *bo,
>  {
>  	struct amdgpu_device *adev = amdgpu_ttm_adev(bo->bdev);
>  	struct amdgpu_bo *abo = ttm_to_amdgpu_bo(bo);
> +	struct amdgpu_ttm_buffer_entity *entity;
>  	struct amdgpu_copy_mem src, dst;
>  	struct dma_fence *fence = NULL;
>  	int r;
> @@ -412,8 +413,12 @@ static int amdgpu_move_blit(struct ttm_buffer_object *bo,
>  	src.offset = 0;
>  	dst.offset = 0;
>  
> +	int e = atomic_inc_return(&adev->mman.next_move_entity) %
> +				  adev->mman.num_move_entities;
> +	entity = &adev->mman.move_entities[e];

Similar to clears this could be a sepatate function, but not a must have.

Reviewed-by: Christian König <christian.koenig@....com> either way.

Regards,
Christian.

> +
>  	r = amdgpu_ttm_copy_mem_to_mem(adev,
> -				       &adev->mman.move_entities[0],
> +				       entity,
>  				       &src, &dst,
>  				       new_mem->size,
>  				       amdgpu_bo_encrypted(abo),
> @@ -426,7 +431,7 @@ static int amdgpu_move_blit(struct ttm_buffer_object *bo,
>  	    (abo->flags & AMDGPU_GEM_CREATE_VRAM_WIPE_ON_RELEASE)) {
>  		struct dma_fence *wipe_fence = NULL;
>  
> -		r = amdgpu_fill_buffer(&adev->mman.move_entities[0],
> +		r = amdgpu_fill_buffer(entity,
>  				       abo, 0, NULL, &wipe_fence, fence,
>  				       AMDGPU_KERNEL_JOB_ID_MOVE_BLIT);
>  		if (r) {
> @@ -2179,7 +2184,8 @@ u32 amdgpu_ttm_set_buffer_funcs_status(struct amdgpu_device *adev, bool enable)
>  	struct ttm_resource_manager *man = ttm_manager_type(&adev->mman.bdev, TTM_PL_VRAM);
>  	uint64_t size;
>  	int r, i, j;
> -	u32 num_clear_entities, num_move_entities, windows, w;
> +	u32 num_clear_entities, num_move_entities;
> +	u32 windows, w;
>  
>  	num_clear_entities = adev->sdma.num_instances;
>  	num_move_entities = MIN(adev->sdma.num_instances, TTM_NUM_MOVE_FENCES);
> @@ -2205,6 +2211,7 @@ u32 amdgpu_ttm_set_buffer_funcs_status(struct amdgpu_device *adev, bool enable)
>  		}
>  
>  		adev->mman.num_move_entities = num_move_entities;
> +		atomic_set(&adev->mman.next_move_entity, 0);
>  		for (i = 0; i < num_move_entities; i++) {
>  			r = drm_sched_entity_init(&adev->mman.move_entities[i].base,
>  						  DRM_SCHED_PRIORITY_NORMAL, &sched,
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h
> index 781b0bdca56c..4844f001f590 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h
> @@ -76,6 +76,7 @@ struct amdgpu_mman {
>  	atomic_t next_clear_entity;
>  	u32 num_clear_entities;
>  	struct amdgpu_ttm_buffer_entity move_entities[TTM_NUM_MOVE_FENCES];
> +	atomic_t next_move_entity;
>  	u32 num_move_entities;
>  
>  	struct amdgpu_vram_mgr vram_mgr;