[PATCH v5 2/2] drm/amdgpu: Add address alignment support to DCC buffers

Marek Olšák maraeo at gmail.com
Wed Jul 17 03:44:06 UTC 2024


AMDGPU_GEM_CREATE_GFX12_DCC is set on 90% of all memory allocations, and
almost all of them are not displayable. Shouldn't we use a different way to
indicate that we need a non-power-of-two alignment, such as looking at the
alignment field directly?

Marek

On Tue, Jul 16, 2024, 11:45 Arunpravin Paneer Selvam <
Arunpravin.PaneerSelvam at amd.com> wrote:

> Add address alignment support to the DCC VRAM buffers.
>
> v2:
>   - adjust size based on the max_texture_channel_caches values
>     only for GFX12 DCC buffers.
>   - used AMDGPU_GEM_CREATE_GFX12_DCC flag to apply change only
>     for DCC buffers.
>   - roundup non power of two DCC buffer adjusted size to nearest
>     power of two number as the buddy allocator does not support non
>     power of two alignments. This applies only to the contiguous
>     DCC buffers.
>
> v3:(Alex)
>   - rewrite the max texture channel caches comparison code in an
>     algorithmic way to determine the alignment size.
>
> v4:(Alex)
>   - Move the logic from amdgpu_vram_mgr_dcc_alignment() to gmc_v12_0.c
>     and add a new gmc func callback for dcc alignment. If the callback
>     is non-NULL, call it to get the alignment, otherwise, use the default.
>
> v5:(Alex)
>   - Set the Alignment to a default value if the callback doesn't exist.
>   - Add the callback to amdgpu_gmc_funcs.
>
> v6:
>   - Fix checkpatch error reported by Intel CI.
>
> Signed-off-by: Arunpravin Paneer Selvam <Arunpravin.PaneerSelvam at amd.com>
> Acked-by: Alex Deucher <alexander.deucher at amd.com>
> Acked-by: Christian König <christian.koenig at amd.com>
> Reviewed-by: Frank Min <Frank.Min at amd.com>
> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.h      |  6 ++++
>  drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c | 36 ++++++++++++++++++--
>  drivers/gpu/drm/amd/amdgpu/gmc_v12_0.c       | 15 ++++++++
>  3 files changed, 55 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.h
> b/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.h
> index febca3130497..654d0548a3f8 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.h
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.h
> @@ -156,6 +156,8 @@ struct amdgpu_gmc_funcs {
>                                       uint64_t addr, uint64_t *flags);
>         /* get the amount of memory used by the vbios for pre-OS console */
>         unsigned int (*get_vbios_fb_size)(struct amdgpu_device *adev);
> +       /* get the DCC buffer alignment */
> +       u64 (*get_dcc_alignment)(struct amdgpu_device *adev);
>
>         enum amdgpu_memory_partition (*query_mem_partition_mode)(
>                 struct amdgpu_device *adev);
> @@ -363,6 +365,10 @@ struct amdgpu_gmc {
>         (adev)->gmc.gmc_funcs->override_vm_pte_flags                    \
>                 ((adev), (vm), (addr), (pte_flags))
>  #define amdgpu_gmc_get_vbios_fb_size(adev)
> (adev)->gmc.gmc_funcs->get_vbios_fb_size((adev))
> +#define amdgpu_gmc_get_dcc_alignment(_adev) ({                 \
> +       typeof(_adev) (adev) = (_adev);                         \
> +       ((adev)->gmc.gmc_funcs->get_dcc_alignment((adev)));     \
> +})
>
>  /**
>   * amdgpu_gmc_vram_full_visible - Check if full VRAM is visible through
> the BAR
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
> b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
> index f91cc149d06c..aa9dca12371c 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
> @@ -512,6 +512,16 @@ static int amdgpu_vram_mgr_new(struct
> ttm_resource_manager *man,
>                 vres->flags |= DRM_BUDDY_RANGE_ALLOCATION;
>
>         remaining_size = (u64)vres->base.size;
> +       if (bo->flags & AMDGPU_GEM_CREATE_VRAM_CONTIGUOUS &&
> +           bo->flags & AMDGPU_GEM_CREATE_GFX12_DCC) {
> +               u64 adjust_size;
> +
> +               if (adev->gmc.gmc_funcs->get_dcc_alignment) {
> +                       adjust_size = amdgpu_gmc_get_dcc_alignment(adev);
> +                       remaining_size = roundup_pow_of_two(remaining_size
> + adjust_size);
> +                       vres->flags |= DRM_BUDDY_TRIM_DISABLE;
> +               }
> +       }
>
>         mutex_lock(&mgr->lock);
>         while (remaining_size) {
> @@ -521,8 +531,12 @@ static int amdgpu_vram_mgr_new(struct
> ttm_resource_manager *man,
>                         min_block_size = mgr->default_page_size;
>
>                 size = remaining_size;
> -               if ((size >= (u64)pages_per_block << PAGE_SHIFT) &&
> -                   !(size & (((u64)pages_per_block << PAGE_SHIFT) - 1)))
> +
> +               if (bo->flags & AMDGPU_GEM_CREATE_VRAM_CONTIGUOUS &&
> +                   bo->flags & AMDGPU_GEM_CREATE_GFX12_DCC)
> +                       min_block_size = size;
> +               else if ((size >= (u64)pages_per_block << PAGE_SHIFT) &&
> +                        !(size & (((u64)pages_per_block << PAGE_SHIFT) -
> 1)))
>                         min_block_size = (u64)pages_per_block <<
> PAGE_SHIFT;
>
>                 BUG_ON(min_block_size < mm->chunk_size);
> @@ -553,6 +567,24 @@ static int amdgpu_vram_mgr_new(struct
> ttm_resource_manager *man,
>         }
>         mutex_unlock(&mgr->lock);
>
> +       if (bo->flags & AMDGPU_GEM_CREATE_VRAM_CONTIGUOUS &&
> +           bo->flags & AMDGPU_GEM_CREATE_GFX12_DCC) {
> +               struct drm_buddy_block *dcc_block;
> +               u64 dcc_start, alignment;
> +
> +               dcc_block = amdgpu_vram_mgr_first_block(&vres->blocks);
> +               dcc_start = amdgpu_vram_mgr_block_start(dcc_block);
> +
> +               if (adev->gmc.gmc_funcs->get_dcc_alignment) {
> +                       alignment = amdgpu_gmc_get_dcc_alignment(adev);
> +                       /* Adjust the start address for DCC buffers only */
> +                       dcc_start = roundup(dcc_start, alignment);
> +                       drm_buddy_block_trim(mm, &dcc_start,
> +                                            (u64)vres->base.size,
> +                                            &vres->blocks);
> +               }
> +       }
> +
>         vres->base.start = 0;
>         size = max_t(u64, amdgpu_vram_mgr_blocks_size(&vres->blocks),
>                      vres->base.size);
> diff --git a/drivers/gpu/drm/amd/amdgpu/gmc_v12_0.c
> b/drivers/gpu/drm/amd/amdgpu/gmc_v12_0.c
> index fd3ac483760e..4259edcdec8a 100644
> --- a/drivers/gpu/drm/amd/amdgpu/gmc_v12_0.c
> +++ b/drivers/gpu/drm/amd/amdgpu/gmc_v12_0.c
> @@ -542,6 +542,20 @@ static unsigned gmc_v12_0_get_vbios_fb_size(struct
> amdgpu_device *adev)
>         return 0;
>  }
>
> +static u64 gmc_v12_0_get_dcc_alignment(struct amdgpu_device *adev)
> +{
> +       u64 max_tex_channel_caches, alignment;
> +
> +       max_tex_channel_caches =
> adev->gfx.config.max_texture_channel_caches;
> +       if (is_power_of_2(max_tex_channel_caches))
> +               alignment = (max_tex_channel_caches / SZ_4) *
> max_tex_channel_caches;
> +       else
> +               alignment = roundup_pow_of_two(max_tex_channel_caches) *
> +                               max_tex_channel_caches;
> +
> +       return (u64)alignment * SZ_1K;
> +}
> +
>  static const struct amdgpu_gmc_funcs gmc_v12_0_gmc_funcs = {
>         .flush_gpu_tlb = gmc_v12_0_flush_gpu_tlb,
>         .flush_gpu_tlb_pasid = gmc_v12_0_flush_gpu_tlb_pasid,
> @@ -551,6 +565,7 @@ static const struct amdgpu_gmc_funcs
> gmc_v12_0_gmc_funcs = {
>         .get_vm_pde = gmc_v12_0_get_vm_pde,
>         .get_vm_pte = gmc_v12_0_get_vm_pte,
>         .get_vbios_fb_size = gmc_v12_0_get_vbios_fb_size,
> +       .get_dcc_alignment = gmc_v12_0_get_dcc_alignment,
>  };
>
>  static void gmc_v12_0_set_gmc_funcs(struct amdgpu_device *adev)
> --
> 2.25.1
>
>
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