Nouveau Might Add A "NvReclock" Option
A patch has been proposed to introduce a NvReclock option for more easily enabling NVIDIA GPU core/memory re-clocking support by this open-source, reverse-engineered driver where supported. Initially this NvReclock option is only going to be enabled by default for select GPUs.
Ilia Mirkin, one of the most prolific Nouveau contributors in recent times, has published a patch that would add the NvReclock option to the Nouveau DRM driver to allow the user to easily enable/disable re-clocking support. You don't need to read many Phoronix articles to know about the re-clocking troubles with the open-source Nouveau driver. This patch doesn't do anything to improve the re-clocking situation, but simply exposes this new boolean option for easily toggling the support.
This patch though will enable Nouveau's basic re-clocking support by default for NVIDIA NVAA/NVAC graphics processors. The "NVAA" codename from Nouveau is representative of the MCP77/MCP78 chipsets with the products being the GeForce 8100, 8200, 8300 mGPU / nForce 700a series, and 8200M G. The "NVAC" hardware is again for integrated graphics with the MCP79/MCP7A chipsets powering the ION, GeForce 9300, 9400 mGPU / nForce 700i series, 8200M G, 9100M, and 9400M (G). It's easier re-clocking this hardware since it's just dealing with the graphics processor and not any dedicated video memory. Since it seems to work well for this hardware, it will be enabled by default.
Ilia Mirkin wrote in the patch, "[Ben Skeggs, Nouveau DRM maintainer], I know you've been saying that reclocking is in a pretty bad state, but I do think that there are going to be groups of people for whom the current code can work at least a little bit. May as well let them try it. The memory script execution is still behind the extra-special flag as well..."
Sadly, there's nothing new to report at this time on Nouveau re-clocking for the newer NVIDIA Fermi and Kepler GPUs that comprise the GeForce 400/500/600/700 series graphics cards. Re-clocking is one of the most challenge aspects to implement; even when it has come to re-clocking / dynamic power management support with the Radeon DRM driver it's been a challenge and there they have paid developers with documentation from AMD to work with for implementing this important feature. Until re-clocking is working for Nouveau, its performance is particularly gruesome compared to the NVIDIA blob. You can read my article from early 2012 about Nouveau Reclocking: Buggy, But Can Boost Performance while on Sunday I have out new Nouveau vs. NVIDIA Linux graphics driver benchmarks.
If today's patch gets pulled the NvReclock option will be found with the next kernel release cycle, the Linux 3.16 kernel.
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