Data Mixing Agent: Learning to Re-weight Domains for Continual Pre-training

Fuente: arXiv
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Main Authors: Yang, Kailai, Liu, Xiao, Ji, Lei, Li, Hao, Liang, Xiao, Liu, Zhiwei, Gong, Yeyun, Cheng, Peng, Yang, Mao
Format: Preprint
Published: 2025
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author Yang, Kailai
Liu, Xiao
Ji, Lei
Li, Hao
Liang, Xiao
Liu, Zhiwei
Gong, Yeyun
Cheng, Peng
Yang, Mao
author_facet Yang, Kailai
Liu, Xiao
Ji, Lei
Li, Hao
Liang, Xiao
Liu, Zhiwei
Gong, Yeyun
Cheng, Peng
Yang, Mao
contents Continual pre-training on small-scale task-specific data is an effective method for improving large language models in new target fields, yet it risks catastrophic forgetting of their original capabilities. A common solution is to re-weight training data mixtures from source and target fields on a domain space to achieve balanced performance. Previous domain reweighting strategies rely on manual designation with certain heuristics based on human intuition or empirical results. In this work, we prove that more general heuristics can be parameterized by proposing Data Mixing Agent, the first model-based, end-to-end framework that learns to re-weight domains. The agent learns generalizable heuristics through reinforcement learning on large quantities of data mixing trajectories with corresponding feedback from an evaluation environment. Experiments in continual pre-training on math reasoning show that Data Mixing Agent outperforms strong baselines in achieving balanced performance across source and target field benchmarks. Furthermore, it generalizes well across unseen source fields, target models, and domain spaces without retraining. Direct application to the code generation field also indicates its adaptability across target domains. Further analysis showcases the agents' well-aligned heuristics with human intuitions and their efficiency in achieving superior model performance with less source-field data.
format Preprint
id arxiv_https___arxiv_org_abs_2507_15640
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Data Mixing Agent: Learning to Re-weight Domains for Continual Pre-training
Yang, Kailai
Liu, Xiao
Ji, Lei
Li, Hao
Liang, Xiao
Liu, Zhiwei
Gong, Yeyun
Cheng, Peng
Yang, Mao
Machine Learning
Artificial Intelligence
Computation and Language
Continual pre-training on small-scale task-specific data is an effective method for improving large language models in new target fields, yet it risks catastrophic forgetting of their original capabilities. A common solution is to re-weight training data mixtures from source and target fields on a domain space to achieve balanced performance. Previous domain reweighting strategies rely on manual designation with certain heuristics based on human intuition or empirical results. In this work, we prove that more general heuristics can be parameterized by proposing Data Mixing Agent, the first model-based, end-to-end framework that learns to re-weight domains. The agent learns generalizable heuristics through reinforcement learning on large quantities of data mixing trajectories with corresponding feedback from an evaluation environment. Experiments in continual pre-training on math reasoning show that Data Mixing Agent outperforms strong baselines in achieving balanced performance across source and target field benchmarks. Furthermore, it generalizes well across unseen source fields, target models, and domain spaces without retraining. Direct application to the code generation field also indicates its adaptability across target domains. Further analysis showcases the agents' well-aligned heuristics with human intuitions and their efficiency in achieving superior model performance with less source-field data.
title Data Mixing Agent: Learning to Re-weight Domains for Continual Pre-training
topic Machine Learning
Artificial Intelligence
Computation and Language
url https://arxiv.org/abs/2507.15640