Qwen3.8 27B

User reports Qwen3.8-27B at FP8 running tensor-parallel across two Radeon AI PRO R9700s, with roughly 1.6k tokens/s prefill and 74-143 tokens/s decode single stream depending on content. Setup is vLLM 0.27.1 in a stilldeadcode/vllm-radiance image with FP8 weights and fp8 KV cache, 262,144 context, 422,964 tokens of KV pool, and RCCL 2.27.7 replacing the image's newer RCCL because one card sits behind the chipset and cannot do PCIe atomics. The decode figure is given as a range, so no single generationTps is recorded. The bundled P2P all-reduce is disabled (RADIANCE_USE_R4D_AR=0) and TP=2 falls back to host-staged collectives; the user notes two CPU-attached cards would keep the P2P path and get better prefill.