Radeon RX 6600/6700/6800 XT: RADV vs. PRO Vulkan Driver Performance
With yesterday's launch day Radeon RX 6600 XT Linux review the benchmarks were conducted using the popular Mesa RADV open-source driver used by many Linux gamers considering it's the driver Valve has been relentlessly optimizing and is the default on most (or all) Linux distributions. For those wondering how the performance of RADV is comparing to that of AMD's closed-source "PRO" Vulkan driver distributed as part of the "Radeon Software for Linux" package, here are some benchmarks exploring that difference.
Today's article is looking at the performance of the latest Mesa RADV performance using Mesa 21.3-devel (via the Oibaf PPA for easy reproducibility) and Linux 5.14 upstream Git against the latest Radeon Software for Linux 21.30 "PRO" driver stack that introduces support for the RX 6600 XT. The 21.30 driver stack released yesterday offers their latest look at their closed-source Vulkan driver that shares its code-base with the AMD Windows Vulkan driver and their closed-source shader compiler back-end.
There is also the AMDVLK open-source Vulkan driver from AMD that does share common code with their "PRO" Vulkan driver but leverages the AMDGPU LLVM shader compiler rather than their internal, closed-source shader compiler back-end. There will be some fresh benchmarks with AMDVLK included next week as well as a fresh look at the RADV performance when forcing on the NGG Culling feature recently merged.
The Radeon RX 6600 XT / RX 6700 XT / RX 6800 XT were tested between this latest upstream open-source and Radeon Software for Linux "PRO" Vulkan driver (including its DKMS kernel driver AMDGPU backport). Unfortunately, I still have no Radeon RX 6900 XT which is why that graphics card hasn't ever been benchmarked on Phoronix.
All of the benchmarks were running off Ubuntu 20.04 LTS. Following some recent Radeon Software for Linux Vulkan driver tests on Ubuntu 21.04, I was informed by AMD there are currently some known performance issues when using their Vulkan driver in a Wayland environment. With time their Wayland issue should be addressed while for now they recommend users stick to running the packaged driver on the supported enterprise Linux distributions.