AMD APU On Linux: Gallium3D Can Be 80%+ As Fast As Catalyst
Right away with Counter-Strike: Source we see the open-source Radeon Gallium3D driver almost running at 85% the speed of the AMD Catalyst binary blob when using Linux 3.13 and Mesa 10.1-devel. There are many R600 Gallium3D driver optimizations found in Mesa 10.0 in particular -- plus the Mesa 10.1-devel code over the past few weeks -- but making a big difference in the open-source driver performance is that the Linux 3.13 kernel enables Radeon Dynamic Power Management by default for most Radeon GPUs. DPM makes a very big difference for APUs since their boot clock speeds tend to be much lower compared to their rated highest-power-state frequencies, which now the Radeon DRM driver can set the hardware to operate at rather than its boot performance state.
For Doom 3 the latest open-source driver code is a heck of a lot better than where it is "out of the box" on Ubuntu 13.10, but Catalyst was still much faster.
With the driver code that will be found in Ubuntu 14.04 LTS for a better "out of the box" Radeon experience, the R600g driver can run at 57% the speed of Catalyst in Nexuiz.
With the very basic OpenArena 0.8.5 game, the open-source driver is now as fast as Catalyst.