Ubuntu 15.04 Tonga AMDGPU vs. Catalyst
Benchmarks by Michael Larabel of Phoronix.com. Linux 4.2 lacks AMDGPU power management for the Radeon R9 285 TONGA.
HTML result view exported from: https://openbenchmarking.org/result/1507258-BE-UBUNTU15083&sor&gru&export=pdf.
Tesseract
Resolution: 1920 x 1080
Unigine Valley
Resolution: 1920 x 1080 - Mode: Fullscreen
Xonotic
Resolution: 1920 x 1080 - Effects Quality: High
GpuTest
Test: Plot3D - Resolution: 1920 x 1080 - Mode: Fullscreen
GpuTest
Test: Triangle - Resolution: 1920 x 1080 - Mode: Fullscreen
Phoronix Test Suite v10.8.5