Qwen3.6-27B-PrismaQuant-5.2bit-vllm

A 5.2 bits-per-parameter mixed-precision quantization of Qwen/Qwen3.6-27B, produced with PrismaQuant. Packaged in the compressed-tensors format for direct serving with vLLM. ~22 GB on disk (5 safetensors shards), including the multi-token prediction (MTP) module and the vision tower.

This model is experimental only and nothing is guarantee except that the time might be wasted even to download.
** If there are issues, tell me. If it is good, tell someone else **

Highlights

  • Benchmarks. On a deterministic, prefix-cache-OFF tool-evaluation harness it match or exceed the rdtand/Qwen3.6-27B-PrismaAURA-5.5bit-vllm baseline while being smaller:

    Model Tool-eval (3 metrics) Size
    This model (PrismaQuant 5.2bpp) 94 / 66.7 / 92.3 22 GB
    PrismaAURA 5.5bit (baseline) 93 / 66.7 / 80.8 23 GB

    Same harness for both, run solo with prefix caching disabled for determinism. The largest gap is on the third metric (92.3 vs 80.8).

Method

PrismaQuant, 5.2 bpp target, mixed-precision:

  • Bit placement by Fisher-diagonal sensitivity allocation — more bits are spent on the parameters the loss is most sensitive to.
  • Per-candidate selection by measured KL against a validated surrogate (the allocator chooses the quantization that minimizes measured output- distribution divergence, rather than relying on a proxy heuristic).
  • Provenance: stock PrismaQuant allocator, run under our production render-stream cost mode.

The result is a heterogeneous mix of element types across tensors:

  • NVFP4 (W4A4) for the bulk of the linear weights,
  • FP8 for sensitivity-flagged tensors,
  • BF16 for the most sensitive / small tensors kept at full precision.

config.json carries the full quantization_config (quant_method: compressed-tensors, format: mixed-precision); the exact per-tensor scheme is described by mixed_native_manifest.json.

Serving (vLLM)

The model loads via vLLMs native compressed-tensors path:

vllm serve JasonW2025/Qwen3.6-27B-PrismaQuant-5.2bit-vllm

For fast GDN / linear-attention (gated-delta) serving, install the optional kernel:

pip install causal_conv1d

(Without it, vLLM falls back to a slower path for the linear-attention layers; correctness is unaffected.)

Contents

  • model-0000{1..5}-of-00005.safetensors + model.safetensors.index.json
  • config.json (with quantization_config), generation_config.json
  • mixed_native_manifest.json (per-tensor precision map)
  • MTP module weights (mtp.*) and the Qwen3.6 vision tower (model.visual.*)
  • tokenizer + chat template

License

Inherited from the base model Qwen/Qwen3.6-27B. Refer to the base model card for the governing license terms.

Provenance (added 2026-07-04 — recorded after the fact, verified from the build environment)

  • Calibration dataset: diverse-v1.jsonl (4.6 MB, sha256[:16] cc76f4a13c413398) — mixed prose/code/math corpus built by tools/build_diverse_calibration.py. Exact bytes archived in the PrismaQuant repo (calibration-datasets/).
  • Known caveat (discovered 2026-07-03, applies retroactively): the Fisher probe consumed only 32x1024 tokens (~3%) of that corpus (the "calibration keyhole"). The result stands on its benchmarks; the caveat matters if you try to attribute the win to the calibration mix.
  • Pipeline: PrismaQuant (Fisher-diagonal allocation, production-render-stream cost, validated-surrogate measured-KL selection, exportable_to_vllm gate); TARGET_BITS selected agentically (5.2 beat the 4.9 KL-kneedle on the agentic harness: 94 vs 89).
  • Benchmark context: deterministic harness (temp 0, prefix caching OFF), June 2026 stack. Scores from other stacks/harnesses are not comparable; see the repo maintainer for the full serve flags.
Downloads last month
196
Safetensors
Model size
19B params
Tensor type
F32
·
BF16
·
F8_E4M3
·
U8
·
Inference Providers NEW
This model isn't deployed by any Inference Provider. 🙋 Ask for provider support

Model tree for JasonW2025/Qwen3.6-27B-PrismaQuant-5.2bit-vllm

Base model

Qwen/Qwen3.6-27B
Quantized
(605)
this model