Qwen3.8-Flash-Next-NVFP4-PLE-MMap-MTP-Spark

Qwen3.8-Flash-Next — NVFP4 · mmap PLE · BF16 KV · MTP (DGX Spark)

A derivative of Qwen/Qwen3.8-Flash-Next built for a single NVIDIA DGX Spark (GB10, sm_121, TP=1):

• NVFP4 (W4A16) weights for the compute-heavy GEMMs;
• the 51.2B-parameter PLE / n-gram table stored outside the model index as packed NVFP4 and read from disk with mmap, one requested row at a time;
• BF16 QSA KV cache — no FP8 KV;
• MTP retained, multimodal (vision) retained, all 31 MTP source tensors preserved;
• served by unmodified upstream vLLM plus an out-of-tree plugin.

Provenance

Layout

model-*.safetensors        248 shards, 228018 tensors, 69.9 GiB
ple_nvfp4/                 128 shards, 26.822 GiB, mmap-only
runtime/                   plugin source, preflight, serve profiles
quantization/              tensor map, fused scales, recipe, SHA256SUMS
validation/                10 JSON artifacts: the evidence behind every claim below

The external PLE table is deliberately absent from model.safetensors.index.json; listing it would make the ordinary vLLM weight loader allocate 320001536 × 160 rows in BF16 (~95 GiB).

Precision

W4A16_NVFP4, block size 16, global scale amax / (6.0 * 448.0).

NVFP4: routed MoE experts, shared-expert projections, QSA q/k/v/o and indexer, GDN in-projections and out-projection, PLE key/value projections, MTP linears, lm_head.

BF16: vision tower and projector, token embedding, norms, routers and shared-expert gates, HyperConnection parameters, GDN and PLE convolution/state tensors — i.e. every non-GEMM or numerically sensitive tensor. The model is NVFP4-dominant, not uniformly FP4.

Fused-layer global scales. vLLM keeps one global scale per fused Linear (weight_scale_2.max() for qkv_proj / gate_up_proj / in_proj_qkvz / in_proj_ba, and w13_weight_scale_2[:, 0] for routed experts). Every member of a fused group is therefore quantized against a shared scale; the validator checks this exactly.

Evidence

Not yet qualified on hardware. Quantization, packaging and the static compatibility audits are complete and reproducible. Nothing in this repository has been booted on a GB10: the 32K instance test, the long-context profiles and the memory envelope are pending, and no serving claim should be made until the corresponding artifact exists under validation/.

Serving

python -m pip install -e runtime/qwen38_nvfp4_mmap_ple
export VLLM_PLUGINS=qwen38_nvfp4_mmap_ple
export QWEN38_PLE_MMAP=1 QWEN38_PLE_THREADS=8
unset VLLM_PLE_CPU_OFFLOAD

MODEL=/path/to/this/checkpoint ./runtime/serve-32k.sh

The launchers run runtime/preflight.py first, which refuses to start unless the checkpoint, PLE manifest, plugin, vLLM revision, device and serving flags all match what was qualified. The PLE table must live on local NVMe: it is paged in on every lookup, and preflight rejects network filesystems.

--kv-cache-dtype bfloat16, TP=1 and disabled prefix caching are requirements, not defaults — see plan.md sections 24-30.

License

Inherits the upstream Qwen/Qwen3.8-Flash-Next license; see LICENSE.