Microsoft’s new DirectX 12 Agility SDK opens the door to direct CPU VRAM access

Why it issues: On Thursday, Microsoft’s Agility SDK growth staff introduced the preview launch of Agility SDK model 1.7.10.0. The brand new model brings builders two new options, GPU add heaps and non-normalized sampling. The updates, along with VRAM resizable base deal with register (BAR), present extra environment friendly VRAM knowledge dealing with throughout the CPU and GPU, in addition to enhancements bettering texture-related data administration and use.

The primary of the brand new options, often known as GPU add heaps, decreases dynamic random entry reminiscence (DRAM) utilization by permitting the CPU to entry the GPU’s video RAM (VRAM). This entry eliminates the necessity for knowledge to be copied from VRAM to DRAM for CPU entry and use. Whereas the influence is at present unknown and requires additional testing, the discount in sources and required knowledge might very nicely translate to new accessible efficiencies for builders and efficiency enhancements for finish customers.

The second characteristic, non-normalized sampling, offers builders with a extra absolute technique to acquire texture sampling knowledge. Texture sampling refers back to the technique used to retrieve knowledge from a selected texture, which is later mixed or processed to create the pattern. The brand new Agility SDK’s non-normalized sampling characteristic strikes away from typical sampling strategies, as an alternative permitting builders to position a sampler utilizing the D3D12_SAMPLER_FLAG_NON_NORMALIZED_COORDINATES flag. When used, the flag refers back to the absolute texel location inside a texture, slightly than being sure by the standard values of 0 and 1. Like GPU add heaps, non-normalized sampling requires thorough testing earlier than any precise advantages could be documented.

GPU add heap depends on the usage of resizable BAR, the PCIE-based know-how that’s accessible throughout a lot of AMD, NVIDIA, and Intel’s newer GPUs. It permits a consumer’s CPU to entry the GPU’s framebuffer, ensuing within the capacity to ship extra belongings per transaction. Transactions that do not use resizable bar are usually restricted to accessing 256MB chunks of VRAM. Testing has proven that resizable BAR’s influence on recreation efficiency can differ, with some video games seeing double-digit efficiency will increase, whereas others see no tangible profit.

Builders requiring Intel driver help for the brand new Agility SDK options can use the Intel Arc & Iris Xe Graphics Driver model 31.0.101.4255 bundle. NVIDIA additionally offers help for the brand new DirectX 12 Agility SDK bundle by way of their Recreation Prepared and Studio Drivers model 531.41. AMD has not but publicly launched a supported model of their driver bundle. Per Microsoft’s announcement, builders inquisitive about early entry to the DirectX 12 Agility SDK-enabled AMD drivers ought to contact their AMD alliance supervisor immediately.