Running 0731 on a single DGX Spark (GB10, 128GB) - working vLLM config, ~10 tok/s, 256K context

#32
by wiklif - opened

I got DeepSeek-V4-Flash-0731 serving on a single GB10 box (ASUS Ascent GX10, 121.6 GiB unified memory) with a vLLM-based stack, and published the full reproducible setup:

https://github.com/lrozewicz/vLLM-Moet-GB10

It builds on the excellent vLLM-Moet (2-bit expert planes with hand-written SASS kernels + an FP4 tier that recovers quality), adapted for unified memory and sm_121.

What I measured on the single unit:

  • ~9.8 tok/s decode with the built-in DSpark speculative head (k=2; note: the recommended k=7 is actually slower on this hardware - 5.1 tok/s)
  • ~500 tok/s prefill (chunked, 2048), 28K-token prompt -> TTFT ~53 s
  • 256K context served (KV pool ~660K tokens; the practical ceiling is prefill time, not memory)
  • first boot ~35 min (one-time quantization of the experts), later boots ~10 min via a persistent cache
  • tool calling (--tool-call-parser=deepseek_v4) and per-request thinking toggle with split reasoning work out of the box, so it is usable as a backend for coding agents

The repo README documents the unified-memory pitfalls that make this non-obvious (pinned host staging, misleading memory metrics, MTP-vs-DSpark head compatibility, etc.), with a measurement behind every config value.

Hope it saves someone the two days it cost me. Feedback and reproduction reports welcome.

It feels like if that was yet underperforming on a DGX Spark, considering that there were reports of people running this new model version with a single 5090 and 12 t/s (with speculative decoding), and also looking at the SM120 performance numbers of vllm-moet? But I have to add that these people for some reason did not bother to get into detail how they were running this new model exactly (inference engine, quantization, etc.).

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