We’re aware of some extra memory usage in the DX12, but 100% more is more than we’ve seen! I think it’s multiple sources that is causing the increase in usage but not all are known. For example, I’ve seen when running Infiltrator in DX12 mode that there are 2 additional 4k x 4k 21.34MB textures that don’t exist when running in DX11 mode. I have not investigated why yet:
DX12
DX11
( 21.34 MB ) d3d12!CResource -> Immediate DDI, Ref count: 1, Use count: 0; Description: Tex2D, (2048 x 2048) (12 Mips), DXGI_FORMAT_B8G8R8A8_TYPELESS (0n90), Committed, Implicit heap; More information
( 21.34 MB ) d3d11!NDXGI::CResource -> d3d11!CTexture2D -> Immediate DDI, Ref count: 1, Use count: 1; Description: Tex2D, (2048 x 2048) (12 Mips), DXGI_FORMAT_B8G8R8A8_TYPELESS (0n90), Default; Bindable: [Input: SRV]; More information
( 21.34 MB ) d3d12!CResource -> Immediate DDI, Ref count: 1, Use count: 0; Description: Tex2D, (4096 x 4096) (13 Mips), DXGI_FORMAT_BC5_UNORM (0n83), Committed, Implicit heap; More information
( 21.34 MB ) d3d12!CResource -> Immediate DDI, Ref count: 1, Use count: 0; Description: Tex2D, (4096 x 4096) (13 Mips), DXGI_FORMAT_BC5_UNORM (0n83), Committed, Implicit heap; More information
Do you know where 4k x 4k 13 mip BC5 textures might be coming from?
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-22939 in the post.