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Main Authors: Zhao, Wanru, Chen, Yihong, Tang, Yuzhi, Ma, Wentao, Hu, Shengchao, Hu, Shell Xu, Iacob, Alex, Mehrotra, Abhinav, Lane, Nicholas D.
Format: Preprint
Published: 2026
Subjects:
Online Access:https://arxiv.org/abs/2605.05227
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author Zhao, Wanru
Chen, Yihong
Tang, Yuzhi
Ma, Wentao
Hu, Shengchao
Hu, Shell Xu
Iacob, Alex
Mehrotra, Abhinav
Lane, Nicholas D.
author_facet Zhao, Wanru
Chen, Yihong
Tang, Yuzhi
Ma, Wentao
Hu, Shengchao
Hu, Shell Xu
Iacob, Alex
Mehrotra, Abhinav
Lane, Nicholas D.
contents Data curation is a critical yet under-explored area in large language model (LLM) training. Existing methods, such as data selection and mixing, operate in an offline paradigm, detaching themselves from training. This separation introduces engineering overhead and makes the curation brittle: the entire pipeline must be re-run under model/task shifts. Moreover, offline methods alter data size through hard filtering or resampling, often sacrificing data diversity and harming generalization. We propose to rethink data curation as an online reweighting problem, where sample importance is dynamically adjusted during training via loss weighting rather than static pre-processing. Specifically, we introduce ADAPT (Adaptive Data reweighting for Pretraining and FineTuning), a dynamic online framework that reweights training samples with adaptive per-sample learning rates guided by similarity-based quality signals, without changing the number of training samples. Unlike offline methods that enforce a static data distribution, ADAPT acts as an implicit curriculum learner, progressively shifting focus from coarse-grained patterns to fine-grained semantic distinctions as the model evolves. Experiments on both instruction tuning and large-scale pretraining show that ADAPT consistently outperforms offline selection/mixing and prior online methods, achieving stronger cross-benchmark generalization under equal FLOPs.
format Preprint
id arxiv_https___arxiv_org_abs_2605_05227
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Rethinking Data Curation in LLM Training: Online Reweighting Offers Better Generalization than Offline Methods
Zhao, Wanru
Chen, Yihong
Tang, Yuzhi
Ma, Wentao
Hu, Shengchao
Hu, Shell Xu
Iacob, Alex
Mehrotra, Abhinav
Lane, Nicholas D.
Machine Learning
Artificial Intelligence
Data curation is a critical yet under-explored area in large language model (LLM) training. Existing methods, such as data selection and mixing, operate in an offline paradigm, detaching themselves from training. This separation introduces engineering overhead and makes the curation brittle: the entire pipeline must be re-run under model/task shifts. Moreover, offline methods alter data size through hard filtering or resampling, often sacrificing data diversity and harming generalization. We propose to rethink data curation as an online reweighting problem, where sample importance is dynamically adjusted during training via loss weighting rather than static pre-processing. Specifically, we introduce ADAPT (Adaptive Data reweighting for Pretraining and FineTuning), a dynamic online framework that reweights training samples with adaptive per-sample learning rates guided by similarity-based quality signals, without changing the number of training samples. Unlike offline methods that enforce a static data distribution, ADAPT acts as an implicit curriculum learner, progressively shifting focus from coarse-grained patterns to fine-grained semantic distinctions as the model evolves. Experiments on both instruction tuning and large-scale pretraining show that ADAPT consistently outperforms offline selection/mixing and prior online methods, achieving stronger cross-benchmark generalization under equal FLOPs.
title Rethinking Data Curation in LLM Training: Online Reweighting Offers Better Generalization than Offline Methods
topic Machine Learning
Artificial Intelligence
url https://arxiv.org/abs/2605.05227