Proprietary vs. Linux Git, Mesa 11.2-devel, DRI3 For R600g/RadeonSI
First up is the demanding Unigine Valley benchmark.
Interestingly, the performance of the HD 6870 did the best compared to the proprietary driver: the performance was about the same while with the HD 6950 VLIW4 GPU the performance was still a bit behind. With the AMD GCN GPUs on the RadeonSI Gallium3D driver, the HD 7950, R9 290, and R7 370 were upwards of 80% the speed of the proprietary driver.
With the BioShock Infinite game there was a significant difference in performance between the two driver stacks. The open-source driver stack on the tested graphics cards was around half the speed of the proprietary offering.
With DiRT Showdown, the AMDGPU-using cards didn't run since they were only having OpenGL 3.0 compliance. Additionally, the HD 7950 didn't run as for this game it would end up losing its display short way through the demo test. The HD 6870 didn't run since on the open-source driver only has OpenGL 3.3 support, albeit it's been reported that there are work-arounds through environment variable overrides. For the cards that did handle this racing game on the latest open-source stack, their results were competitive with Catalyst 15.9 offered on Ubuntu 15.10.