Qwen3.6-27B-MTPLX-Optimized-Speed-Vision

Qwen3.6-27B MTPLX Optimized Speed (Vision-Enabled)

A unified local model that both codes at the Qwen3.6-27B level and processes images/videos, packaged for Apple Silicon via MTPLX native speculative decoding with Multi-Token-Prediction (MTP).

This repository restores the multimodal vision tower that is typically stripped in text-only MLX/MTPLX conversions.

Architecture

• Body: 4-bit affine, group size 64 (from Youssofal/Qwen3.6-27B-MTPLX-Optimized-Speed)
• MTP sidecar (mtp/weights.safetensors): Prequantized MTP heads with a 3-bit affine group-64 draft-only LM head.
• Vision tower (vision_tower.safetensors, 333 tensors, bf16 unquantized): Extracted verbatim from the official checkpoint's own model.visual.* weights (shards 7 and 8 of Qwen/Qwen3.6-27B) and renamed to the vision_tower.* prefix for MTPLX native VLM compatibility (~879 MB).

Usage (MTPLX)

mtplx start --model <path-to-this-model-dir> --port 8092 \
  --chat-template-path <path-to-this-model-dir>/chat_template.jinja

Serves an OpenAI-compatible endpoint supporting both text and image input payloads via POST /v1/chat/completions.

The MTPLX CLI defaults to mtp_history_policy=committed, which this model requires for healthy deep-position acceptance. The model's recommended draft sampler is temperature 0.7 (see recommended_draft_sampler in mtplx_runtime.json); pass --draft-temperature 0.7 to match.

Performance (measured)

Apple M5 Pro 64 GB, MTPLX 1.0.4, temperature 0.6, mtp_history_policy=committed, --draft-temperature 0.7 (model recommended), thinking OFF, warm (4 warmup prompts discarded), 8 measured prompts from the calibration_coding suite, max_tokens=192, median tok/s.

Two throughput definitions are reported:

• tok/s (wall-clock e2e) = generated_tokens / total_elapsed, includes prompt prefill. The real end-to-end speed and the honest denominator for the speedup ratio.
• tok/s (decode-only) = generated_tokens / decode_elapsed, excludes prefill.

Acceptance is stable across runs: greedy draft (temp 0.0) gives 0.874/0.740/0.636, recommended draft (temp 0.7) gives 0.900/0.759/0.648, both within noise. Vision graft has zero acceptance cost relative to the text-only source (Youssofal/Qwen3.6-27B-MTPLX-Optimized-Speed measures identical acceptance 0.874/0.740/0.636 under the same config).

Earlier baked mtplx_runtime.json figures (acceptance 1.0/0.98/0.94, ~63 tok/s) were measured on Apple M5 Max 128 GB and are not reproducible on M5 Pro 64 GB due to lower memory bandwidth; they are preserved in the historical_m5max field of mtplx_runtime.json for traceability. The vision tower is lazy-loaded (only when a request carries an image), so text-only throughput is unaffected by it. Numbers are indicative, not a benchmark suite.

Sources And Attribution