2016 End-of-Year Open-Source Radeon Benchmarks With Linux 4.9, Mesa 13.1-dev On Many Different GPUs
Metro Last Light Redux is OpenGL4-only on Linux, thus the limitation on the cards that could be tested. The HD 6950, HD 5830, and V8800 on R600g were coming up short of 60 FPS.
Or you can punish the graphics cards hard by running Metro Last Light Redux at 4K.
Portal remains very much playable on all of the cards tested at 1080p.
Portal at 4K is still pretty easy.