R600 Radeon Gallium3D Gets More SB Back-End Work
Written by Michael Larabel in AMD on 17 July 2013 at 12:19 PM EDT. 1 Comment
Vadim Girlin has merged another set of patches concerning his "SB" shader optimization back-end for the R600 Gallium3D driver, including some code that has the potential to affect the performance.

The R600 SB back-end can improve OpenGL performance for the open-source AMD Radeon Linux graphics driver. However, this back-end isn't the default as AMD views the future with their LLVM compiler back-end, etc. While it's not the default, those early users of Mesa 9.2 have been quick to play with the performance-enhancing code as it's just a matter of setting the R600_DEBUG=sb environment variable.

For those users of the R600 SB back-end, Vadim merged a number of commits into Mesa Git master today. The commits can be found via a CGit query.

Notable to today's commits is ALU packing work for AMD Radeon HD 6900 "Cayman" GPUs. The R600 SB scheduler/register allocator was designed around Evergreen VLIW-5 hardware and is suboptimal for VLIW-4 hardware, but Girlin has now made some improvements that may benefit Cayman GPUs.

Other commits today include fixes for multi-slot instructions on Cayman, fixing the debug dump code for the scheduler, an initial register allocation fix, and some other items.

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Michael Larabel is the principal author of Phoronix.com and founded the site in 2004 with a focus on enriching the Linux hardware experience. Michael has written more than 10,000 articles covering the state of Linux hardware support, Linux performance, graphics drivers, and other topics. Michael is also the lead developer of the Phoronix Test Suite, Phoromatic, and OpenBenchmarking.org automated benchmarking software. He can be followed via Twitter or contacted via MichaelLarabel.com.

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