Qwen3.8-27B MTPLX Optimized Speed — M3 Max Q4 G64
An MLX 4-bit affine group-size-64 quantization of the official Qwen/Qwen3.8-27B weights, packaged for MTPLX 2.6.0 native MTP inference on Apple Silicon.
What is included
- Quantized trunk: 4-bit affine, group size 64 (
model-00001...00003.safetensors). - Native MTP sidecar:
mtp.safetensors, intentionally retained in BF16. - MTP runtime contract:
mtplx_runtime.json, architectureqwen3-next-mtp. - Tokenizer, chat template, generation config and model index.
The MTP sidecar is required. Do not delete it or re-quantize it as a generic MLX artifact if you want native speculative decoding.
Provenance and license
- Base model:
Qwen/Qwen3.8-27B. - Source format: official BF16 native weights.
- Conversion: MTPLX Forge 2.6.0, performed locally on 2026-08-15.
- Quantization recipe: body
Q4, affine, group size64; MTP policykeep_bf16. - License: Apache-2.0. This derivative must retain the upstream
LICENSEand attribution.
This is an independently produced quantization, not an official Qwen or MTPLX release.
Requirements
- Apple Silicon Mac with sufficient unified memory; this package occupies about 15 GB on disk.
- MTPLX 2.6.0 or newer with
qwen3-next-mtpsupport. - This package is intended for MTPLX, not oMLX 0.5.3 direct loading. That oMLX version does not support this native MTP package.
Run
mtplx quickstart \
--model /path/to/Qwen3.8-27B-MTPLX-Optimized-Speed-M3Max-Q4G64 \
--host 127.0.0.1 --port 18001 \
--profile sustained \
--mtp --depth 3 \
--scheduler-mode serial --batching-preset solo \
--reasoning off --preserve-thinking off \
--max-tokens 8192 --no-stats-footer --yes
The service is OpenAI-compatible at http://127.0.0.1:18001/v1. Confirm that response mtplx_stats includes generation_mode: "mtp", runtime_mtp_enabled: true and draft_head_installed: true.
Validation notes
Forge contract validation recognized qwen3-next-mtp and passed quality checks. Its depth-2 validation sample measured 21.99 tok/s versus an 18.53 tok/s autoregressive baseline (1.187x). This is a conversion/quality-validation figure, not the recommended serving benchmark: the Forge harness uses a specific prompt, a conservative comparison setup and does not represent the final depth-3 MTPLX service profile.
On the M3 Max 128 GB deployment that produced this artifact, MTPLX 2.6.0 sustained with native MTP depth 3 completed a 512-token API decode test at 33.9 tok/s end-to-end. Interactive UI observations reached 40+ tok/s instantaneous/rolling peak. Neither number is a cross-machine guarantee: decode speed depends strongly on prompt and completion length, MTP acceptance, memory pressure, MTPLX version and measurement method. Report the completion length, prompt length and whether a number is decode-only, end-to-end average or rolling peak when comparing results.
The recommended starting profile is sustained with depth 3. Test depth 2 and depth 3 against your own workload; MTP can lose its advantage on some prompts when draft acceptance falls.
Known limitations
- The MTP sidecar is BF16 by design, so disk/memory characteristics differ from a fully generic 4-bit MLX conversion.
- MTP is not guaranteed to accelerate every prompt; low acceptance can remove the benefit.
max-tokenslimits one response, not model context capacity.- A long idle period followed by a first request includes model loading and warm-up time.
Citation
Please cite the upstream Qwen3.8 model and link this derivative repository when redistributing or benchmarking it.