The RadeonSI performance is now in good shape but there's still some optimizations remaining for maximizing the open-source potential out of AMD's modern GPUs. The RadeonSI-based hardware was still unable to run Xonotic with higher quality image settings in Xonotic due to register allocation issues with the AMD GPU LLVM back-end.
Stay tuned for the NVIDIA and Intel results that will accompany the AMD Radeon performance numbers in the days ahead. Overall, the Ubuntu 14.04 LTS open graphics experience is decent with Linux 3.13 and Mesa 10.2-devel although Linux gamers and enthusiasts are encouraged to either use the proprietary drivers or at least upgrade to the latest Linux kernel (3.14+) and Mesa 10.2-devel for the best OpenGL performance and best feature-set.
Run your own performance comparisons against all the graphics cards in this article in a very easy and fully-automated manner with the Phoronix Test Suite by simply executing phoronix-test-suite benchmark 1404040-PL-RADEONBUN78.
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