AMDGPU Linux 4.5 DRM Tuning Tests With DRI2/DRI3, PowerPlay, Semaphores, Scheduler
As has been shown already, PowerPlay has the largest impact on performance for the GCN 1.2+ cards supported by AMDGPU. Without PowerPlay, the AMDGPU discrete graphics cards have been limited to running at their boot clock frequencies rather than being able to re-clock to their highest performance states.
For the other tuning tests on the R9 285, these options didn't have much of an impact on the Metro Redux games.
There wasn't much to see either out of OpenArena.
With Tesseract we see that enabling semaphores increased the performance for this open-source game. Also, when the AMDGPU scheduler was disabled, the performance dropped quite noticeably.