With word this week that there's some performance improvements for the open-source Radeon Linux graphics driver to be found with the Linux 3.8 kernel as a result of the a-synchronous DMA engine support, some very early benchmarks of the "drm-next" code were done from five different AMD Radeon graphics cards. In extreme cases, the open-source graphics driver can deliver 10x higher OpenGL frame-rates with the experimental kernel.
The "drm-next" pull hasn't even been sent in yet for pulling into Linus Torvalds' tree for the Linux 3.8 kernel, but the drm-next Git repository from David Airlie was benchmarked on 13 December. This drm-next kernel was compared to the vanilla Linux 3.7 kernel for a quick look at what's on the horizon for Linux 3.8 open-source AMD graphics performance. While the a-synchronous DMA engine support is there on the kernel side, for exploiting its full capabilities is also user-space support that has yet to be integrated into the mainline repositories.
Aside from the a-sync DMA code for the Radeon DRM driver in Linux 3.8, see this Phoronix article for details on other Radeon driver changes to be merged into this next Linux kernel release.
This quick Linux 3.7 vs. drm-next benchmarking was done on the Radeon HD 4770, HD 5750, HD 6450, HD 6570, and HD 6870 graphics cards. Additional graphics card benchmarks will come from the Linux 3.8 kernel as the development cycle progresses.
The Radeon OpenGL benchmarks were done with the Phoronix Test Suite and the user-space during this DRM testing was Mesa 9.1-devel Git from 13 December and the xf86-video-ati 7.0.0 DDX driver. SwapBuffersWait was disabled for the ATI DDX.