Microsoft Adds Residency Management To Mesa's D3D12 Code For Better Efficiency

The newest code Microsoft has contributed to Mesa for its D3D12 driver, which is used for running OpenGL / OpenGL ES / OpenCL (and eventually Vulkan) over Direct3D 12 for use on Windows and WSL2, is Direct3D residency management support.

The Direct3D 12 and WDDM2 driver model residency integration is around informing the kernel driver when a resource is no longer used. The residency management integration within the Mesa code in turn will allow for some performance and efficiency optimizations, especially for games/applications that may over-commit memory but not use all of that memory constantly.

This D3D12 residency management code in Mesa will allow for faster OpenGL performance when its approaching memory over-commitment and can then demote some resources down to system RAM, lower overhead of resource allocation, the ability to stall the GPU rather than the CPU when residency requests are pending, and decreasing overhead on the application thread itself. Microsoft's own Minecraft game was among the software tested and finding a performance improvement.

More details on this D3D12 residency management can be found via this merge request now part of Mesa 22.1 for improving this OpenGL support over D3D12 on Windows/WSL.