TL;DR
Table with columns: Checkpoint, basic ("capital of France?"), thinking| Checkpoint | basic ("capital of France?") | thinking |
|---|
| v1 of this repo (Open-Platypus calibration) and most community AWQ | ❌ empty content (model loops in <think> until max_tokens) | ❌ |
| v2 (current) | ✅ "Paris" with finish_reason=stop, 45 reasoning tokens | ✅ engages thinking, terminates cleanly on simple QA |
Why this exists
The default AWQ calibration recipes (Open-Platypus, ShareGPT, etc.) have no <think> traces in the assistant turns. When you quantize with that data, the model never sees a </think> followed by an answer in calibration, so it loses the ability to terminate the thinking block. Result: validate_capabilities.py basic test ("What is the capital of France? Answer in one word.") returns empty content because all 2048 generated tokens live inside an unclosed <think> block — SGLang's --reasoning-parser qwen3 strips those into reasoning_content and you get back nothing in content.
This checkpoint was calibrated with a thinking-aware mixed dataset:
with tokenizer.apply_chat_template(..., enable_thinking=True) so the <think>...</think> structure appears in every render. 256 samples × 1024 tokens, GPTQ via llmcompressor (CPU, ~6h on AMD Ryzen 9 7900), then converted to native AWQ format.
Sampling — IMPORTANT
Do NOT use temperature=0 (greedy decode) — Qwen3-family models loop on greedy: "Paris\n</think>\nParis\n</think>...". Use the model's recommended sampling, which SGLang picks up automatically via sampling_defaults='model':
temperature=0.7
top_p=0.95
top_k=20
Validator confirms temperature=0.6 with chat_template_kwargs={"enable_thinking": true} produces clean output.
Validation results
validate_capabilities.py --skip-vision --skip-video (from the calibration repo):
[PASS] basic finish=stop answer='paris' (45 reasoning tokens, was BROKEN on original)
[~] thinking reasoning_seen answer_ok (model derives correct $0.05 for the
ball-and-bat puzzle in ~400 reasoning
tokens at temp=0.6; verbose at temp=0.7
— bumped validator budget to 4096 tok)
Thinking on simple QA terminates in tens of tokens. Hard reasoning (multi-step math) the model is verbose at recommended sampling — the answer ends up inside the reasoning block before finish_reason=stop. This is much better than the original AWQ where the model never terminated even on trivial questions.
Architecture
- Base: Qwen/Qwen3.5-27B (multimodal
Qwen3_5ForConditionalGeneration, 48 layers, hybrid DeltaNet + full-attention)
- Quantization: AWQ 4-bit, group_size=128
- Excluded from quantization (kept BF16):
lm_head, DeltaNet in_proj_a/in_proj_b (recurrent state — INT4 destroys it), vision tower
- Format: native AWQ (
qweight + scales + qzeros). Loadable by SGLang's AWQ Triton + HIP GEMV kernels.
- Vision weights preserved:
model-vision.safetensors carries the BF16 vision tower + preprocessor_config.json is included so multimodal inference still works.
Files
Table with columns: File, What it is| File | What it is |
|---|
model.safetensors (+ index.json) | AWQ language-model weights |
model-vision.safetensors | BF16 vision tower (untouched, preserved from base) |
chat_template.jinja | Original Qwen3.5 template (supports enable_thinking) |
tokenizer.json, tokenizer_config.json | Stock Qwen3.5 tokenizer |
| , |
SGLang launch (RDNA4)
MODEL=mattbucci/Qwen3.5-27B-AWQ-4bit-calibrated python -m sglang.launch_server \
--model-path $MODEL \
--tensor-parallel-size 2 \
--dtype float16 \
--kv-cache-dtype fp8_e4m3 \
--context-length 262144 \
--quantization awq \
--reasoning-parser qwen3 \
--disable-cuda-graph \
--disable-custom-all-reduce \
--disable-overlap-schedule \
--attention-backend triton
Or via the reference launcher: MODEL=$MODEL ./scripts/launch.sh qwen35
Single-user, FP8 KV cache, --disable-cuda-graph:
Table with columns: Context, tok/s, TTFT| Context | tok/s | TTFT |
|---|
| 128 | 26 | 5s |
| 16K | 18.7 | 8.7s |
| 32K | 15.3 | 20s |
| 65K | 13.0 | 47s |
| 131K | 9.5 | 100s |
| 256K | 5.8 | 209s |
Dense DeltaNet hybrid — bandwidth-bound at short context, full-attention layers dominate at long. For 256K agent workloads, prefer Qwen3.6-35B-A3B MoE (12-13 tok/s @ 256K).
Calibration repo
All scripts, validator, and benchmark code: github.com/mattbucci/2x-R9700-RDNA4-GFX1201-sglang-inference — see scripts/quantize/quantize_qwen35_thinking_aware.py and scripts/quantize/calibration_datasets.py.
License
Apache 2.0, inherited from the base model.