After enjoying a two month holiday, Valve-funded Mike Blumenkrantz is back to working on Mesa's Zink code that implements OpenGL (and via Clover even OpenCL) atop the Vulkan API. Zink has shown it can be quite competitive in its OpenGL performance atop Vulkan compared to dedicated OpenGL drivers and in 2023 should be maturing into even better shape.

Kicking things off in the new year, Blumenkrantz is working on Zink's support for the VK_EXT_descriptor_buffer extension -- a spec he's been working on with the Vulkan working group as part of Valve. The VK_EXT_descriptor_buffer extension was made public in mid-November as part of Vulkan 1.3.235 .

The VK_EXT_descriptor_buffer extension introduces new commands for putting shader accessible descriptors directly in memory. VK_EXT_descriptor_buffer was worked on by engineers from Valve, AMD, NVIDIA, Arm, and Intel for making the management of descriptor data more useful. Some Vulkan drivers like RADV already support the extension.

Valve's VKD3D-Proton 2.8 added support for the VK_EXT_descriptor_buffer extension to help with CPU overhead. Blumenkrantz is looking forward to VK_EXT_descriptor_buffer usage with Zink too as it will help further reduce CPU overhead, allow for more direct control over vRAM allocations, and avoid potentially unnecessary flushing.

Mike has written more about this latest Zink work on his blog . There is a merge request that was opened yesterday for Mesa to add Zink descriptor buffer utilization. In there he notes a 3~5% performance improvement for performance and memory to OpenGL games like Tomb Raider as a result of this work.