Re: 答复: [PATCH 1/2] drm/amdgpu: disable the VRAM manager on special placements v2

[Christian König]

> Here , checking place->lpfn , is that mean if required place is located in visible vram, driver run none pages split code path?
Yes, exactly. CPU accessible allocations weren't meant to be split with 
the initial implementation.

For this we need to be able map scattered allocations into the CPU VM 
page tables first.

You kind of implemented this, but it would still cause a ping/pong of 
the BO inside the visible VRAM space.

We would need to move the handling of 
AMDGPU_GEM_CREATE_CPU_ACCESS_REQUIRED from amdgpu_ttm_placement_init() 
down into the VRAM manager as well.

Regards,
Christian.

Am 07.11.2016 um 03:10 schrieb Qu, Jim:
> HI Christian:
>
>          if (bo->flags & AMDGPU_GEM_CREATE_VRAM_CONTIGUOUS ||
> -           amdgpu_vram_page_split == -1) {
> +           place->lpfn || amdgpu_vram_page_split == -1) {
>                  pages_per_node = ~0ul;
>                  num_nodes = 1;
>          } else {
>
> Here , checking place->lpfn , is that mean if required place is located in visible vram, driver run none pages split code path?
> if so, seem it comes back to the starting point. In extreme cases, allocate visible vram fail.
>
> Thanks
> JimQu
>
> ________________________________________
> 发件人: amd-gfx <amd-gfx-bounces at lists.freedesktop.org> 代表 Christian König <deathsimple at vodafone.de>
> 发送时间: 2016年11月4日 19:00
> 收件人: amd-gfx at lists.freedesktop.org
> 主题: [PATCH 1/2] drm/amdgpu: disable the VRAM manager on special placements v2
>
> From: Christian König <christian.koenig at amd.com>
>
> This disables the VRAM manager when a special placement is requested, otherwise
> we play ping/pong with the buffers on every command submission.
>
> v2: only check lpfn
>
> Signed-off-by: Christian König <christian.koenig at amd.com>
> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
> index 180eed7c..d710226 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
> @@ -108,7 +108,7 @@ static int amdgpu_vram_mgr_new(struct ttm_mem_type_manager *man,
>                  lpfn = man->size;
>
>          if (bo->flags & AMDGPU_GEM_CREATE_VRAM_CONTIGUOUS ||
> -           amdgpu_vram_page_split == -1) {
> +           place->lpfn || amdgpu_vram_page_split == -1) {
>                  pages_per_node = ~0ul;
>                  num_nodes = 1;
>          } else {
> --
> 2.5.0
>
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