More AMD GPU LLVM Back-End Improvements For RadeonSI Coming
Written by Michael Larabel in Radeon on 7 November 2014 at 07:50 AM EST. 15 Comments
Tom Stellard has more improvements coming for AMD's GPU LLVM back-end that can yield performance improvements.

Tom began tackling LLVM machine scheduler support for RadeonSI within AMD's R600/AMDGPU back-end. In the process of the machine scheduler enablement he started enabling register pressure tracking in the scheduler so it's able to use a register pressure reduction strategy once a threshold is reached.

For testing the difference he's been running Phoronix Test Suite tests and he's found that several of the benchmarks ae faster with the machine scheduler enabled. However, for at least Xonotic Ultra there is a lock-up issue still being worked through. Unfortunately he didn't share any results on so we don't know exactly how far the performance has improved with his LLVM back-end enhancements.

The test code that enables the machine scheduler for AMD GCN hardware can be found via this Git repository. Tom commented on the work via his personal blog. Presumably the AMD GPU machine scheduler support will be integrated in time for the LLVM 3.6 release in the months ahead.
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Michael Larabel is the principal author of and founded the site in 2004 with a focus on enriching the Linux hardware experience. Michael has written more than 20,000 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 automated benchmarking software. He can be followed via Twitter or contacted via

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