Fujitsu One Compression (3 min read)
Key point
Fujitsu has released OneComp, an open-source Python library that improves the quantization accuracy of LLMs.
Details
Fujitsu One Compression (OneComp) is an open-source Python library for Post-Training Quantization (PTQ) of large language models (LLMs). It supports state-of-the-art algorithms such as GPTQ, DBF, and RTN, and in particular implements Quantization Error Propagation (QEP), a new method presented at NeurIPS 2025.
Key features are as follows:
- QEP (Quantization Error Propagation): Propagates quantization error to subsequent layers to correct the model's accuracy.
- vLLM plugin integration: Enables DBF and Mixed-GPTQ quantized models to be served immediately on vLLM.
- AutoBit: Provides mixed-precision quantization that automatically allocates per-layer bit widths based on available VRAM.
- JointQ: Jointly optimizes weight allocation and scale parameters to improve quantization accuracy.
- LoRA SFT post-processing: Uses LoRA adapters to recover the accuracy of quantized models or inject domain-specific knowledge.
- Rotation preprocessing: Learns rotation matrices based on SpinQuant/OstQuant to minimize quantization error.
It has currently been validated on Llama (TinyLlama, Llama-2, Llama-3) and Qwen3 (0.6B–32B) architectures. With just a single line of code, users can automate the entire process from model quantization to evaluation (Perplexity and Accuracy) and model saving.
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