Earlier this week was the How Ubuntu 16.04 Is Performing With AMDGPU/Radeon Graphics Compared To Ubuntu 14.04 With FGLRX, which showed off some interesting open-source Radeon Linux driver results but the Radeon R9 285 "Tonga" graphics card at the time couldn't be tested on Ubuntu 16.04's kernel due to a regression. That issue is fortunately now resolved in the latest Xenial Xerus kernel so here are those numbers.
With the latest Linux 4.4 kernel sent down to Ubuntu 16.04 users, which still has all of the back-ported AMDGPU/Radeon changes from Linux 4.5, the AMD Tonga issue has been resolved and the graphics card is now able to successfully boot. So in continuation of the earlier article, here are the R9 285 results from Ubuntu 14.04.4 when using the Catalyst (fglrx) driver and then when running Ubuntu 16.04 plus Linux 4.4 (with the 4.5 back-ports) and Mesa 11.2 built against LLVM 3.8. The xf86-video-ati 7.6.1 is the DDX currently packaged for Ubuntu Xenial.
The rest of the setup is the same as in the earlier article. All of these OpenGL benchmarks were carried out in a fully-automated and reproducible manner using the open-source Phoronix Test Suite benchmarking software.