AMD Is Trying To Optimize Their Gallium3D Driver Even Further With Lower Overhead
RadeonSI Gallium3D allows for maximizing the OpenGL performance out of Radeon graphics cards under Linux. There has even been various remarks about the prospects of porting RadeonSI to Windows given how well this open-source OpenGL driver performs. We have seen various RadeonSI optimizations continue with newer Mesa releases even while newer Linux game ports tend to be Vulkan exclusive and Steam Play's DXVK/VKD3D-Proton are routing all newer Windows games on Linux by way of Direct3D over Vulkan.
Stemming from the recent discussions over looking at dropping the classic Mesa DRI drivers from mainline to focus on Gallium3D drivers and Vulkan, well known and longtime open-source AMD R300g/R600g/RadeonSI developer Marek Olšák came out in support of this plan. In commenting in response to the proposal for phasing out those classic Mesa drivers, Marek had an interesting remark to share with regards to AMD's continued optimization work for RadeonSI:
We still have some CPU overhead performance targets we haven't reached. One of them is to decrease CPU overhead for one benchmark 4 times compared to everything we already have in master. I don't know how we are going to do that, but we'll try.
Dropping the classic Mesa drivers would help in allowing core Mesa code to be better adapted to a Gallium3D-only OpenGL world and being able to reduce a lot of cruft that has built up over the years. In turn that modernization work and other easier restructuring with the classic drivers removed could help in allowing for lower driver overhead than otherwise could be easily achieved.
Marek hadn't elaborated on their precise performance targets. Presumably though these still ongoing performance targets are with regard to workstation OpenGL usage.
In recent months we have seen Marek and other open-source AMD Mesa developers working in particular on optimizing for SPECViewPerf and other workstation OpenGL scenarios. Workstation customers have been one of the remaining holdouts where AMD's proprietary OpenGL driver is still seemingly important compared to Mesa while since the latter part of last year we've seen a lot more RadeonSI/Gallium3D optimizations in this area.
Given how quickly new Linux games are making use of Vulkan and how Steam Play is primarily relying on Vulkan for newer Windows games, it would make sense if their remaining RadeonSI performance targets are for workstation OpenGL software. OpenGL remains quite common meanwhile among the workstation ISVs that are slow to adapt to new APIs and other invasive changes. Meanwhile with pretty much every OpenGL Linux game we benchmark, RadeonSI has been performing excellent for some time. In any case, it's great to see the game is not over yet for AMD's relentless RadeonSI Gallium3D optimizations.