2D Color Tiling Patches Hit For Radeon R600+
Minutes after publishing the Mesa 8.0 Radeon Gallium3D benchmarks against Catalyst, first-stage patches were posted for proper 2D color tiling support for modern Radeon hardware from, which can result in double-digit performance gains.
2D color tiling support has already been available for the R300 through R500 ATI GPUs, but now the proper support is finally coming for the R600 (Radeon HD 2000) series through Cayman (Radeon HD 6900) series. The 2D color tiling can dramatically speed-up the graphics performance in some areas, but this support has required a fair amount of work. To implement, this requires patches to the Linux kernel (Radeon DRM), Mesa, xf86-video-ati DDX, and libdrm. In other words, the entire stack.
Previously the R600+ ASICs only had enabled 1D color tiling support (it's been a work-in-progress since 2010). 2D color tiling is faster than the 1D mode, but will likely not be enough to put the R600+ hardware on the same level of performance as the proprietary Catalyst Linux driver.
Jerome Glisse worked on the R600+ 2D tiling support. These first patches are not for mainline inclusion at the moment but rather to review the kernel API and looking at using the Radeon's libdrm code as a common place for all surface allocation work.
Besides patching the entire stack, Color2DTiling must also be enabled from the xorg.conf file. This feature is not expected to become the default for one year or more.
The 2D color tiling changes on the Radeon DRM side will be too late for inclusion into the Linux 3.3 kernel by the time the other developers sign off on the work. On the Mesa side those changes are now also too late for Mesa 8.0. In other words, for most users running their stock distribution packages, you won't be seeing this performance-enhancing feature until updates in H2'2012 or later. This work will hopefully land in the Linux 3.4 kernel and Mesa 8.1.
Phoronix performance tests of the R600 through Cayman 2D color tiling patches should be ready in the next few days. More information is available from Jerome's mailing list announcement.
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