Qwen3.8 125B (6B active) Flash-Next

User reports completing a full 262,144-token sequence with Qwen3.8-Flash-Next on 2× RTX 4090 24 GB, with a boundary run of 261,991 input + 128 output tokens in 123.3 s (≈2,150 input tok/s). Setup is vLLM (v0.5.0 image) with TP2/EP2, 256K context, hot 84 profile, CPU_OFFLOAD_GB=30, MTP_DEPTH=3, and fast-256k switches; peak VRAM was ~23.8 GiB per card. Decode measured 80–90 tok/s (mean ≈86) with the SM 8.9 gate patch, prefill 1,772–1,814 tok/s at ~14K and 2,294–2,316 tok/s at ~61K; the user notes the x8/x8 PCIe bifurcation likely caps stream-staging and that hot 88 OOM'd on an earlier build.