Running Radeon RX Vega On Linux 4.15, NVIDIA/Radeon Benchmarks
With AMDGPU DC having been merged a few days ago for the Linux 4.15 merge window, it's now possible to run the Radeon RX Vega graphics cards with display support using the mainline kernel without having to resort to using a patched/third-party kernel build or using the AMDGPU-PRO hybrid driver. Here are some tests I have carried out with the Radeon RX Vega 56, RX Vega 64, and other graphics cards from Linux 4.15 Git compared to a few NVIDIA GPUs.
With the DC display code having landed, this was the last big piece of the Vega open-source driver puzzle not mainline (except for still the rest of the compute support not yet being mainline in the respective places). So to get RX Vega cards working on say Ubuntu 17.10, it's just as easy as now grabbing a 4.15-based kernel from the Ubuntu Mainline Kernel archive.
Ubuntu 17.10 ships with Mesa 17.2 so I would definitely recommend upgrading to at least Mesa 17.3 for the newest performance work and optimizations, if not Mesa 17.4-dev. That can be easily done via Padoka or one of the other PPAs. With the Padoka PPA you will currently get Mesa 17.4-dev built against LLVM 6.0 SVN for the best open-source Radeon experience at the moment. If you are not on Ubuntu 17.10 but an older release, you will also need to fetch the latest AMDGPU firmware binary files from linux-firmware.git for Vega support.
On Ubuntu or others if you are using Linux 4.15 Git, recent Mesa/AMDGPU LLVM, and have the Vega firmware blobs present, the RX Vega support should be running nicely on all mainline components. It is for me in my tests over the past few days including with different HDMI/DP connections to different monitors; some Phoronix readers in the forums have been reporting of some recent DC display regressions, but presumably should be fixed soon enough in the Linux 4.15-rc releases.
From this Linux 4.15 Git + Mesa 17.4-dev stack, I ran some fresh RadeonSI OpenGL and RADV Vulkan benchmarks with the Radeon RX 580, R9 Fury, RX Vega 56, and RX Vega 64. On the NVIDIA side these results were compared to using the 387.22 display driver and with the GeForce GTX 1060, GTX 1070, GTX 1080, and GTX 1080 Ti. These Ubuntu 17.10 gaming tests were done with the Core i7 8700K Coffee Lake system with ASUS PRIME Z370-A motherboard, 16GB DDR4-3000, and Intel Optane 900p SSD + Crucial MX300 525GB SSD.