[PATCH] drm/amdgpu: Place new CPU-accessbile BOs in GTT if visible VRAM is full

[Marek Olšák]

On Fri, May 19, 2017 at 9:03 AM, Michel Dänzer <michel at daenzer.net> wrote:
> On 19/05/17 12:04 PM, John Brooks wrote:
>> Set GTT as the busy placement for newly created BOs that have the
>> AMDGPU_GEM_CREATE_CPU_ACCESS_REQUIRED flag, so that they don't cause
>> established BOs to be evicted from visible VRAM.
>
> This is an interesting idea, but there are some issues with this patch.
>
>
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
>> index 365883d..655718a 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
>> @@ -392,6 +392,17 @@ int amdgpu_bo_create_restricted(struct amdgpu_device *adev,
>>  #endif
>>
>>       amdgpu_fill_placement_to_bo(bo, placement);
>> +
>> +     /* This is a new BO that wants to be CPU-visible; set GTT as the busy
>> +      * placement so that it does not evict established BOs from visible VRAM.
>> +      */
>> +     if (domain & (AMDGPU_GEM_DOMAIN_VRAM | AMDGPU_GEM_DOMAIN_GTT) &&
>
> Should be something like
>
>         if (domain == (AMDGPU_GEM_DOMAIN_VRAM | AMDGPU_GEM_DOMAIN_GTT) &&
>
> otherwise it would also match e.g. BOs with domain ==
> AMDGPU_GEM_DOMAIN_GTT and the AMDGPU_GEM_CREATE_CPU_ACCESS_REQUIRED
> flag set (not that this makes sense, but there's nothing to prevent it).

I think it should be like this, which trivially rules out GTT and
VRAM|GTT cases:
if (domain == AMDGPU_GEM_DOMAIN_VRAM &&

Marek