Swift-Qwen3.8-27B NVFP4 GGUF

A llama.cpp GGUF of ukisai/Swift-Qwen3.8-27B-NVFP4, UkisAI's calibrated NVFP4 checkpoint of Swift-Qwen3.8-27B (a reasoning-efficient fine-tune of Qwen3.8-27B). UkisAI publish that NVFP4 checkpoint for vLLM only; this file brings it to llama.cpp without requantizing any of its NVFP4 weights.

File Size BPW
Swift-Qwen3.8-27B-NVFP4-Q8mix.gguf 19.72 GB 5.77

Tensor layout

Tensors Type Source
All MLP (64 layers × gate/up/down) + full attention q/k/v/o (16 layers) — 256 tensors NVFP4 UkisAI's llm-compressor NVFP4, byte-identical to the checkpoint (with per-tensor scales)
Gated DeltaNet linear attention (attn_qkv, attn_gate, ssm_out, 48 layers) Q8_0 BF16 in the checkpoint
output (lm_head), token_embd Q8_0 BF16 in the checkpoint
MTP head (blk.64, incl. nextn.eh_proj) Q8_0 BF16 in the checkpoint
ssm_alpha, ssm_beta, ssm_conv1d F32 BF16 in the checkpoint (lossless)

The MTP head is included, so --spec-type draft-mtp works.

How it was made

With the official ghcr.io/ggml-org/llama.cpp:full image (build b10975):

  1. convert_hf_to_gguf.py --outtype bf16 on the checkpoint. It has a single nvfp4-pack-quantized config group, which the converter repacks natively as GGML NVFP4.
  2. llama-quantize with an exact per-tensor --tensor-type-file: NVFP4 tensors map to nvfp4, which llama-quantize copies unchanged when source and target types match; the BF16 leftovers go to Q8_0, the recurrent gates to F32.
  3. Verified: all 256 NVFP4 tensors and their 512 scale tensors are SHA-256 identical to the conversion of the checkpoint, and all 20 qwen35.* architecture metadata keys match UkisAI's own GGUF of Swift.

Usage

llama-server -m Swift-Qwen3.8-27B-NVFP4-Q8mix.gguf \
  --mmproj mmproj-Swift-Qwen3.8-27B-F16.gguf \
  --spec-type draft-mtp --spec-draft-n-max 3 \
  -c 262144 -fa on --jinja
  • NVFP4 runs natively on NVIDIA Blackwell. Other GPUs need a llama.cpp build with an NVFP4 fallback path.
  • Vision: use the projector from ukisai/Swift-Qwen3.8-27B-GGUF (mmproj-Swift-Qwen3.8-27B-F16.gguf).
  • Chat template: reasoning_effort accepts xhigh (default), medium, low. Unlike some Qwen templates, it does not accept high.
  • Sampling (stored in the GGUF header): temperature 1.0, top_p 0.95, top_k 20, min_p 0.

Quality

Not yet measured for this file. UkisAI report the source NVFP4 checkpoint within sampling noise of BF16 on their vLLM harness (MTP acceptance 61% vs 62%). For reference, UkisAI's own GGUF tiers measure KLD vs BF16 of 0.0120 (Q4_K_M), 0.0056 (Q5_K_M), 0.0020 (Q6_K), 0.0009 (Q8_0) on wikitext @512.

License

Swift weights are under the Swift Open License v1.0: free for personal, research, educational, evaluation and commercial use by individuals and organizations with annual recurring revenue (including affiliates) up to US$1,000,000. Above that, commercial use requires a Swift Enterprise License from UkisAI. See the source model card.

All credit for the model and the NVFP4 calibration goes to UkisAI; the base model is Qwen/Qwen3.8-27B by the Qwen team.

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