---
license: apache-2.0
library_name: xllm
pipeline_tag: text-generation
tags:
- xllm
- looped-language-model
- paper-part2
- dense
---

# d4-m

Table 4, M, D4 of *Towards Looped Models Done Right. Part II: Rethinking at Fixed Points*.

> [!IMPORTANT]
> **Loading this checkpoint requires the xLLM code.** The weights are stored in xLLM's native
> format (BF16 Safetensors with an xLLM `config.json` and `artifact_manifest.json`). This is not a
> Hugging Face `transformers` checkpoint: `AutoModel.from_pretrained` cannot load it.
> Get the code at [https://github.com/ifm-ai/xllm-loop](https://github.com/ifm-ai/xllm-loop) and load the directory with `xllm.paper_part2.artifacts.load_artifact`.

## Model details

| | |
| --- | --- |
| Model | dense Transformer of 4 blocks, untied output layer; width 3,072, 48 heads (12 KV heads), SwiGLU FFN 8,704 |
| Parameters | 810,052,608, including the embedding and output layers |
| Evaluation | full KV cache |
| Training | recipe `m_d4`: 20,480 updates of 512 x 8,192 tokens (85.90B), AdamW, warmup-stable-decay |
| Weights | BF16 Safetensors: the training checkpoint's FP32 weights rounded to BF16 |
| Tokenizer | `tokenizer/`, the Jais64k tokenizer of training |

## Download

```bash
hf download IFM/LoopedLM-P2-d4-m --local-dir d4-m
```

The xLLM loader checks the directory against `artifact_manifest.json`: it rejects symbolic links
and files the manifest does not list, apart from the `.gitattributes` file and the
`.cache/huggingface/` folder that `hf download --local-dir` adds. Download into a directory as
above, not into the Hub cache (`~/.cache/huggingface/hub`), whose files are symbolic links.

## Use

Evaluate with `eval_paper_part2.py` from the xLLM repository:

```bash
ENABLE_FLASH_ATTENTION_3=true python eval_paper_part2.py --artifact d4-m \
    --data /path/to/eval-data/data.json --out out ppl
```

`data.json` and the evaluation inputs come from `release/paper-part2/prepare-eval-data.py
--output /path/to/eval-data`.

`xllm.paper_part2.artifacts.load_artifact("d4-m")` verifies the directory and returns the model
config fields and the BF16 state dict on CPU.

`artifact_manifest.json` records the size and SHA-256 of every file in this repository.

## Paper and citation

*Towards Looped Models Done Right. Part II: Rethinking at Fixed Points*: https://arxiv.org/abs/2610.06833

```bibtex
@article{huang2026fixedpoints,
  title   = {Towards Looped Models Done Right, Part II: Rethinking at Fixed Points},
  author  = {Benhao Huang and Chufan Shi and Junlin Chen and Shicheng Wen and Zhengzhong Liu and Eric Xing and Xuezhe Ma},
  journal = {arXiv preprint arXiv:2610.06833},
  year    = {2026}
}
```

## License

The weights are released under the Apache License 2.0 (`LICENSE`); `NOTICE` records the
tokenizer's attribution and how the artifact was prepared. The xLLM code is distributed under its
own license.