Let's take an except from an article compairing open source (Gallium3D & Nouveau) drivers to proprietary AMD & nVidia drivers on Linux:
First up with Nexuiz, we see the open-source R600 Radeon Gallium3D driver for HD 5000/6000 series graphics cards is generally the better part of 50% the speed of the Catalyst Linux driver. The Radeon HD 6870 performance was surprisingly at 82% the speed of the binary blob.
The Radeon HD 7000 series performance is quite poor for now as its Radeon Gallium3D driver is still being brought up but its performance will also improve on the Linux 3.11 kernel due to dynamic power management / re-clocking.
The open-source NVIDIA driver (Nouveau) performance continues to be quite slow too, in large part as well due to re-clocking. Unfortunately, there's still no mainline re-clocking support for the NVIDIA Fermi / Kepler (GeForce 400/500/600/700) GPUs with the open-source Nouveau driver.
So, the HD 5000 series is 3 years old, and yet the open source driver cannot match the proprietary AMD driver in every test, same goes for nVidia cards and their driver as well. So tell us again why AMD should make their Windows drivers open source?
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