Here's the third installment of our Windows vs. Linux OpenGL benchmarking this week... This is a look at how the AMD Catalyst closed-source driver on Windows compares to AMD's latest open-source driver code on Linux.
Following the Intel Skylake Graphics: Windows 10 vs. Ubuntu Linux Performance and NVIDIA OpenGL: Windows 10 Pro vs. Ubuntu Linux Benchmarks is now a fresh look at the cross-platform performance for AMD Radeon graphics cards. This testing today is with the closed-source driver on Windows 10 Pro x64 and the open-source driver on Ubuntu 15.10 Linux.
Originally the plan was to also test the Catalyst driver on Ubuntu 15.10 too, but those efforts were thwarted. While a patched Catalyst now works with Ubuntu 15.10, the Skylake system I was using for testing ran into a strange issue when trying Catalyst on Ubuntu 15.10. Once booted with any of the AMD cards tested, the Dell 4K monitor would lose its signal when trying both HDMI and DisplayPort. This didn't happen with non-Skylake systems and wasn't a problem in the other AMD configurations tested for this article, while nothing out of the ordinary was reported to dmesg or the Xorg.0.log to explain this odd display problem. As a result, this is an interesting comparison with just looking at the open-source AMD driver on Linux, which tends to be preferred anyways by Phoronix readers.
Under Windows, the latest Catalyst driver release at the time of testing is Catalyst 15.11 Beta, which was used for this article. On Linux, Catalyst 15.9 remains the latest public driver from mid-September. The open-source driver configuration tested was Ubuntu 15.10 with the Linux 4.3 kernel, xf86-video-ati 7.5.99 DDX, and Mesa 11.1-devel from the Padoka PPA that includes the LLVM 3.8 SVN AMDGPU back-end.
The graphics cards used for this comparison were just the Radeon HD 7950 and Radeon R9 290. Only two cards were used due to the limited different AMD Radeon models I have on hand and not being able to run a proper comparison with newer GCN GPUs like the Radeon R9 285 and Radeon R9 Fury. With the current mainline driver code on Linux, power management / re-clocking isn't supported and thus with the open-source driver the performance is very slow compared to Catalyst. Coincidentally, this morning AMD published the initial PowerPlay AMDGPU support but it's too late for this article and that code won't be merged now until Linux 4.5. However, in a separate article I'll run some tests specifically looking at this AMDGPU experimental PowerPlay support.
All benchmarks for this article were facilitated using the open-source Phoronix Test Suite benchmarking software with OpenGL tests that fit our testing requirements and were compatible with both Catalyst on Windows and the open-source RadeonSI Gallium3D driver.