gpt-oss 21B (3.6B active)

User reports gpt-oss-20b at 65.4 t/s generation and 861 t/s prompt processing on an AMD Strix Halo 128GB system. Setup is native llama.cpp with the MXFP4 GGUF, flash attention on, mmap off and ngl 99, run through Vulkan (RADV GFX1151) with a 96 GB GPU carve-out of shared memory. Both figures come from llama-bench at depth 8192: PP512 at 860.95 t/s and a separate TG128 at 65.40 t/s, so they are not a same-request prompt/output pair.