Quantization recipe
Table with columns: Setting, Value| Setting | Value |
|---|
| Transformer body | GPTQ-Pro FOEM W4A16 |
| Weight bits | 4 |
| Group size | 128 |
| Symmetric | Yes |
| Activation ordering | Disabled (desc_act=false) |
| Sequential quantization | Enabled |
| Calibration samples | 256 |
| Calibration sequence length | 2048 |
| Calibration mix | Code and reasoning JSONL |
| Quantizer | GPTQModel 6.1.0-dev |
| Pack format | GPTQ, INT32 packing |
The recorded recipe uses activation-weighted MSE, act-group-aware
quantization, FOEM alpha=0.25 and beta=0.2, plus a 0.5% RTN fallback with
MSE smoothing. Full machine-readable settings are available in
quantize_config.json and config.json.
Preserved tensors
The following tensor families were excluded from the 4-bit GPTQ body and kept
in their original precision:
- token embeddings
lm_head
- vision encoder tensors
- MTP tensors
- normalization tensors
The repository includes model-preserved-skips.safetensors as an auxiliary
record of the 15 explicitly preserved tensors. The indexed checkpoint contains
2,399 weights totaling 19,559,449,368 bytes (approximately 18.22 GiB).
vLLM serving
The following text-only profile was validated on one RTX 3090 24 GB. The
runtime was the local residency image
localhost/vllm-openai-nightly-7a1eb8ac2-sleepwake-local:20260617, based on
the pinned upstream vLLM nightly commit
7a1eb8ac2ec4ea69338c51dc7afd4b15010abfa8. Its local changes implement
sleep/wake residency control; they do not alter this checkpoint's
quantization format.
vllm serve XReyRobert/Qwen3.8-27B-GPTQ-Pro-FOEM-4bit-g128-ns256 \
--served-model-name qwen3.8-27b-gptq-pro-foem-4bit-g128-ns256-ctx110k \
--language-model-only \
--dtype float16 \
--quantization gptq_marlin \
--max-model-len 110592 \
--max-num-seqs 1 \
--kv-cache-dtype fp8_e5m2 \
--enable-prefix-caching \
--reasoning-parser qwen3 \
--enable-auto-tool-choice \
--tool-call-parser qwen3_coder \
--max-cudagraph-capture-size 32 \
--gpu-memory-utilization 0.95 \
--trust-remote-code
This validated profile does not use --enforce-eager. The 110,592-token
limit is a single-RTX-3090 deployment result, not a limitation encoded in the
checkpoint.
Vision and MTP weights are present, but enabling either feature changes the
memory budget and requires a separately sized serving profile. Remove
--language-model-only for vision use.
Sampling defaults
The checkpoint carries the Qwen3.8 thinking-mode defaults:
temperature=1.0
top_p=0.95
top_k=20
The validated vLLM deployment also used neutral min_p=0.0 and
repetition_penalty=1.0 defaults.
Longer-context hybrid variant
For single-24-GB-GPU deployments requiring more KV-cache capacity, see
XReyRobert/Qwen3.8-27B-GPTQ-Pro-FOEM-4bit-g128-ns256-INT8-Head-Embeddings.
That derivative keeps this 4-bit GPTQ-Pro transformer body and additionally
quantizes the token embeddings and lm_head to group-size-128 INT8. It was
validated at 210K text-only context, 182K with vision, and 170K with MTP2 on
one RTX 3090 24 GB. It requires the narrow vLLM compatibility patch included
in that repository.
Validation status
- The checkpoint loads with GPTQ-Marlin in the pinned vLLM nightly runtime.
- OpenAI-compatible chat inference, Qwen reasoning parsing, tool-call parsing,
prefix caching, and residency sleep/wake were exercised in deployment.
- Text-only serving was validated with
max_model_len=110592 on one RTX 3090.
- The model card does not currently report standardized quality benchmarks.
Limitations
- Quantization can reduce quality relative to the BF16 base model.
- FP8 KV cache introduces numerical loss independently of weight
quantization.
- Native context length does not guarantee that every serving configuration
fits in available VRAM.
- Vision and MTP paths require separate memory and compatibility validation.
- This checkpoint inherits the capabilities, risks, license, and intended-use
guidance of the original Qwen3.8-27B model.