With the development of large language models (LLMs), there has been an increasing need for significant advancements in handling long contexts. To enhance long-context capabilities, constructing high-quality training data with long-range dependencies is crucial. Existing methods to select long-context data often rely on sentence-level analysis, which can be greatly optimized in both performance and efficiency. In this paper, we propose a novel token-level framework, LongAttn, which leverages the self-attention mechanism of LLMs to measure the long-range dependencies for the data. By calculating token-level dependency strength and distribution uniformity of token scores, LongAttn effectively quantifies long-range dependencies, enabling more accurate and efficient data selection. We filter LongABC-32K from open-source long-context datasets (ArXiv, Book, and Code). Through our comprehensive experiments, LongAttn has demonstrated its excellent effectiveness, scalability, and efficiency. To facilitate future research in long-context data, we released our code and the high-quality long-context training data LongABC-32K.
View on arXiv@article{wu2025_2502.16860,
title={ LongAttn: Selecting Long-context Training Data via Token-level Attention },
author={ Longyun Wu and Dawei Zhu and Guangxiang Zhao and Zhuocheng Yu and Junfeng Ran and Xiangyu Wong and Lin Sun and Sujian Li },
journal={arXiv preprint arXiv:2502.16860},
year={ 2025 }
}