6/19/2023 0 Comments Directx end runtime![]() When creating D3D12 resources, we need to specify D3D12_HEAP_PROPERTIES. Support GPU upload heaps with D3D12_HEAP_TYPE_GPU_UPLOAD ![]() Alternatively this optimization can be done via UMA Optimizations: CPU Accessible Textures and Standard Swizzle. ![]() One reason to use GPU upload heaps on integrated GPUs is that you can use GPU upload heaps instead of using upload + default heaps for resources, so there’s no need to do a lot of copy operations just to put the resource in a different state. Another good reason for D3D12 to expose Resizable BAR is that some performance testing on some platforms has shown that games perform better with resizeable BAR enabled.ĭ3D now decides to support the use of CPU visible VRAM via D3D GPU upload heaps on both discrete and integrated GPUs. With a resizable bar, Windows will renegotiate the size of a GPU’s BAR in WDDM Version 2.0 and later. However, now there are a lot of GPUs that support a resizable base address register(also known as Resizable BAR). So we can’t provide any guarantees around it, at which point it seemed like a bad idea to expose to apps. If app A comes in and allocates all 256MB, then app B wouldn’t be able to allocate any. A bigger problem was that it’s not a properly virtualizable resource. D3D chose not to expose this because the I/O region for a frame buffer is usually only 256MB, which is not that useful. It used to be typical for a discrete GPU to have only a small portion of its frame buffer exposed over the PCI bus. DirectX-Specs D3D12 GPU Upload Heaps Background
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