llama.cpp Enables -ffast-math for Up to 7% Inference Speedup on AMD GPUs
pmttyji · reddit · 2026-07-06
The llama.cpp community submitted a PR to enable the -ffast-math compilation optimization for HIP (AMD GPU) builds. In benchmarks on the RDNA3.5 architecture (gfx1151), the prefill throughput for Qwen3.5-27B Q4KM increased by 4.0%-7.0%, and Qwen3-0.6B BF16 increased by 0.6%-3.4%, while the FA=0 path remained largely unchanged. The PR includes complete cross-context length benchmark data, offering direct reference value for users running local inference on AMD GPUs.
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