Until Re-Clocking Is Figured Out, Nouveau Remains Very Slow Against NVIDIA Linux
Up for sharing today are our benchmarks comparing the very latest open-source Nouveau graphics driver code (Linux 3.15 + Mesa 10.3-devel) against the proprietary NVIDIA Linux graphics driver to see how the two NVIDIA Linux drivers compare.
This article is in continuation of the Intel vs. Radeon vs. Nouveau open-source driver comparison from a few days ago and is similar to the Radeon Gallium3D vs. Catalyst tests conducted on Friday. As mentioned in the original article, with the Linux 3.15 kernel we ran into several Nouveau DRM issues that limited the graphics cards we could use for this NVIDIA Linux performance comparison. There were PGRAPH problems and other issues, which limited us to just testing the GeForce 9800GTX, GT 520, and GTX 760 graphics cards. Still, it's a fairly wide look at the NVIDIA GeForce Linux performance with both old and new, low and high-end GPUs. When the latest Nouveau regressions are addressed, we'll be back with more tests.
On the Nouveau side was the Linux 3.15 Git kernel from this past week plus from the Oibaf PPA was the xf86-video-nouveau 1.0.10 DDX driver and Mesa 10.3.0-devel git-155f98d NV50/NVC0 Gallium3D drivers providing open-source OpenGL 3.3 support. All of this testing was done from a stock Intel Core i7 4770K system running Ubuntu 14.04 LTS x86_64 with the only changes being made between testing was swapping out the driver configuration and graphics cards. For the proprietary driver tests we had the NVIDIA 337.19 Beta driver.
All benchmarking was facilitated using the Phoronix Test Suite. Before getting to the results, it's worth reiterating for any new Phoronix readers that arguably the number one limitation right now for the Nouveau driver is its lack of re-clocking support. This has been an ongoing challenge for Nouveau developers and with pre-Fermi GPUs they have made some progress while for newer Fermi/Kepler hardware their main challenge comes down to video memory re-clocking, it appears. For no NVIDIA graphics cards right now with the Linux 3.15 kernel is any re-clocking enabled by default. As a result, the GeForce 9800GTX runs at 399MHz for its GPU core and vRAM compared to 675/1100MHz (respectively), the GT 520 runs at 270/405MHz rather than 810/500MHz, and the GTX 760 runs at 405/648MHz rather than 980/3004MHz. There's no ETA when we can expect Nouveau re-clocking to be working right for being able to maximize the performance out of the NVIDIA hardware when using this reverse-engineered, open-source driver.