Mesa 22.3 Lands Open-Source Radeon Driver CPU Overhead Optimizations

There have been some notable merges this week for Mesa 22.3, particularly as it concerns the open-source Radeon graphics driver code.

Phoronix readers may recall the recent work by Zink developer Mike Blumenkrantz on reducing the CPU overhead for draw calls. That set of 13 patches are still being reviewed while three of the patches have now been merged as part of a separate merge request by Timur Kristóf of the Valve driver team. Those patches are for always inlining some select RADV functions.

A 4% improvement for now while the additional RADV CPU overhead changes are still being reviewed. Update: A +23% draw improvement from the overhead work as part of SGPR emission has also been merged.

Separately, Marek Olsak who is well known for his AMD OpenGL open-source driver work has merged "lots of cleanups" as well as some CPU overhead improvements. That's a set of two dozen patches including common Mesa code improvements and various glthread overhead optimizations. It was last week Marek enabled RadeonSI OpenGL threading by default with Mesa 22.3.

On the Zink front, Mike Blumenkrantz yesterday merged adding optimal keys for shader variants. That can yield a 20% improvement in Vulkan draw overhead testing.

Another separate set of Mesa changes worth pointing out are assembler updates by Rhys Perry that have been merged for ACO. The RADV ACO code has seen +2279 / -1437 lines of code changed in preparing for GFX11 hardware, a.k.a. RDNA3. It's good seeing RADV/ACO preparing for RDNA3 graphics cards expected to be announced in November.

Overall it's another busy week in Mesa git open-source GPU drivers and it's only Tuesday!