Qwen3.5-397B-A17B-P48NVFP4-MoESQ

A W4A4 + paired-4:8 sparse compressed checkpoint of Qwen/Qwen3.5-397B-A17B, produced with MoESQ. The MoE expert weights are NVFP4 with paired-4:8 structured sparsity. They are stored sparse: only the kept values plus a small mask are on disk, not a dense NVFP4 tensor with zeros in place. The target is NVIDIA Blackwell (SM100) sparse tensor cores.

  • Base model: Qwen/Qwen3.5-397B-A17B (MoE, 512 routed experts with 10 active plus a shared expert, 60 layers with hybrid linear/full attention)
  • Compression: NVFP4 W4A4 plus paired-4:8 sparsity on the routed MoE experts
  • Effective weight precision: about 2 bits/weight on routed-expert linears
  • Checkpoint size: 155.3 GiB, vs 222.7 GiB for the same weights stored as dense NVFP4 (0.70×)
  • Kernel: paired-4:8 sparse NVFP4 grouped GEMM (CUTLASS, SM100) through vLLM's paired48_nvfp4 MoE backend

Links

Usage

This checkpoint does not load in upstream vLLM. The MoESQ repository installs a patched vLLM v0.30.0 (the paired48_nvfp4 MoE backend and sparse-storage loader) together with the kernels. It needs NVIDIA Blackwell (SM100) GPUs and a CUDA toolkit >= 12.8.

git clone --recurse-submodules https://github.com/IST-DASLab/MoESQ.git && cd MoESQ
bash integrations/vllm/install.sh && source .venv-vllm/bin/activate

# 4x B200, tensor + expert parallel
vllm serve ISTA-DASLab/Qwen3.5-397B-A17B-P48NVFP4-MoESQ \
  --tensor-parallel-size 4 --enable-expert-parallel

vLLM selects the backend automatically.

Evaluation

OpenLLM Leaderboard v1: 6-task average

The six tasks are ARC-Challenge (25-shot), HellaSwag (10-shot), MMLU (5-shot), TruthfulQA-MC2 (0-shot), Winogrande (5-shot) and GSM8K (5-shot, greedy). Scores use lm-evaluation-harness with the full test sets, as mean ± std over 3 few-shot seeds (1234, 0, 1). Recovery is computed per seed against dense, then averaged.

Model Avg Recovery vs dense
Qwen3.5-397B-A17B (dense) 80.24 ± 0.14 —
This model (MoESQ) 75.07 ± 0.21 93.55 %
SparseGPT + GPTQ (same W4A4 paired-4:8 target) 70.61 ± 0.25 88.00 %
OBR (same target) 73.42 ± 0.36 91.50 %
JSQ (same target) 62.96 ± 0.14 78.46 %

Most of the gap to the baselines comes from GSM8K, which moves by about ±1.3 points across few-shot seeds. Reasoning benchmarks have not been run for this model yet.

Compression details

Field Value
Weights NVFP4 (E2M1), one FP8-E4M3 scale per 32 dense K elements, FP32 per-tensor global scale
Activations NVFP4, dynamic per-32 group scales, FP32 per-tensor global scale stored per expert linear
Sparsity Paired 4:8 along K: in every 8 consecutive elements (4 pairs), exactly 2 pairs are kept
Compressed layers Routed MoE experts (gate_proj, up_proj, down_proj) in all 60 layers
Left in BF16 lm_head, embeddings, full and linear attention, norms, router (mlp.gate), shared experts, vision tower / merger, the MTP head
Format compressed-tensors, nvfp4-pack-quantized, with a paired48_sparse storage marker

The scale group is 32 because the SM100 sparse NVFP4 MMA requires one scale per 32 dense K elements, which is 16 surviving elements after the 4:8 prune.

Sparse storage layout (paired48_sparse, pair-bitmask v1)

Packed NVFP4 stores two adjacent K elements per byte, so one pair is one byte. A paired-4:8 weight therefore has exactly 2 nonzero bytes in every 4-byte chunk. Each routed-expert linear stores:

Tensor dtype / shape Contents
weight_sparse_packed uint8 [out, K/4] the 2 kept bytes of every 4, in K order
weight_sparse_mask uint8 [out, K/16] 4 bits per 4-byte chunk (exactly 2 set; bit i means byte i is kept); the low nibble is the lower-K chunk
weight_scale float8_e4m3 [out, K/32] block scales (linear layout)
weight_global_scale, input_global_scale float32 per-tensor global scales

quantization_config carries "paired48_sparse": {"layout": "pair-bitmask", "version": 1}. The encoding is lossless: converting to and from dense NVFP4 is exact, and every tensor in this upload was checked with a round trip. At load time vLLM rebuilds each layer's dense packed weight and compresses it into the kernel's own layout.

Recipe (MoESQ, arm "gw2")

The full MoESQ config for this run is in moe_sq_config.yaml.

  • Init: GPTQ, 4-bit, 512 calibration samples, percdamp 0.1, block size 128. Masks come from paired-4:8 pruning.
  • Refinement: masks and weight values are learned jointly for 10 epochs on 8,192 mixed calibration sequences of up to 4,096 tokens, with activations fake-quantized to NVFP4. The objective is the block-output reconstruction error weighted by the router gate (gate_weight_exponent = 2). Learning rates are 2e-4 for masks and 2.5e-5 for weights.

Citation

@article{moesq,
  title   = {Hardware-Native Joint Sparse-Quantization for Trillion-Scale Mixture-of-Experts},
  author  = {TODO},
  journal = {arXiv preprint arXiv:TODO},
  year    = {TODO}
}

Contact

For questions, open a discussion here or contact kwanhee.lee@postech.ac.kr.

Downloads last month
31
Safetensors
Model size
258B params
Tensor type
BF16
·
U8
·
Inference Providers NEW
This model isn't deployed by any Inference Provider. 🙋 Ask for provider support

Model tree for ISTA-DASLab/Qwen3.5-397B-A17B-P48NVFP4-MoESQ

Quantized
(77)
this model

Collection including ISTA-DASLab/Qwen3.5-397B-A17B-P48NVFP4-MoESQ