How Nouveau Compares To NVIDIA's Linux Driver When Kepler Re-Clocking Works
With the upcoming Linux 4.4 kernel, the Kepler re-clocking is in much better shape and for select GeForce GTX 600/700 series cards now allows the open-source driver to run them at their fully-rated clock frequencies. Here's some tests showing how Nouveau now compares to NVIDIA's proprietary Linux driver in such a comparison.
This is a comparison when using the Linux 4.4-rc2 kernel with Nouveau P-State re-clocking enabled and the cards set to their highest performance state (0f). The tests were done with a GeForce GTX 680 that's fully re-clocked and working well now under the Linux 4.4 kernel where as previously it only could reach the 0a performance state. There's also tests done on the GeForce GTX 780 Ti, but here is an example of a card/vBIOS not yet working quite right with the Nouveau driver even though the 0f performance state is reported. This should show both sides of Nouveau's current Kepler re-clocking support with Linux 4.4. Sadly with Linux 4.4 there still is not GeForce GTX 900 Maxwell support. Besides using the Linux 4.4 kernel, Mesa 11.1-devel from the Padoka PPA provided the latest Gallium3D code atop this Ubuntu 15.10 system.
The two NVIDIA graphics cards were compared to the NVIDIA 358.16 proprietary driver on Ubuntu 15.10 Wily's default Linux 4.2 kernel. The OpenGL benchmarks ran for this open vs. closed-source GeForce driver comparison were facilitated in an automated manner using the open-source Phoronix Test Suite benchmarking software.