GradAlign: Gradient-Aligned Data Selection for LLM Reinforcement Learning

Fuente: arXiv
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Auteurs principaux: Yang, Ningyuan, Du, Weihua, Sun, Weiwei, Welleck, Sean, Yang, Yiming
Format: Preprint
Publié: 2026
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author Yang, Ningyuan
Du, Weihua
Sun, Weiwei
Welleck, Sean
Yang, Yiming
author_facet Yang, Ningyuan
Du, Weihua
Sun, Weiwei
Welleck, Sean
Yang, Yiming
contents Reinforcement learning (RL) has become a central post-training paradigm for large language models (LLMs), but its performance is highly sensitive to the quality of training problems. This sensitivity stems from the non-stationarity of RL: rollouts are generated by an evolving policy, and learning is shaped by exploration and reward feedback, unlike supervised fine-tuning (SFT) with fixed trajectories. As a result, prior work often relies on manual curation or simple heuristic filters (e.g., accuracy), which can admit incorrect or low-utility problems. We propose GradAlign, a gradient-aligned data selection method for LLM reinforcement learning that uses a small, trusted validation set to prioritize training problems whose policy gradients align with validation gradients, yielding an adaptive curriculum. We evaluate GradAlign across three challenging data regimes: unreliable reward signals, distribution imbalance, and low-utility training corpus, showing that GradAlign consistently outperforms existing baselines, underscoring the importance of directional gradient signals in navigating non-stationary policy optimization and yielding more stable training and improved final performance. We release our implementation at https://github.com/StigLidu/GradAlign
format Preprint
id arxiv_https___arxiv_org_abs_2602_21492
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle GradAlign: Gradient-Aligned Data Selection for LLM Reinforcement Learning
Yang, Ningyuan
Du, Weihua
Sun, Weiwei
Welleck, Sean
Yang, Yiming
Machine Learning
Artificial Intelligence
Computation and Language
Reinforcement learning (RL) has become a central post-training paradigm for large language models (LLMs), but its performance is highly sensitive to the quality of training problems. This sensitivity stems from the non-stationarity of RL: rollouts are generated by an evolving policy, and learning is shaped by exploration and reward feedback, unlike supervised fine-tuning (SFT) with fixed trajectories. As a result, prior work often relies on manual curation or simple heuristic filters (e.g., accuracy), which can admit incorrect or low-utility problems. We propose GradAlign, a gradient-aligned data selection method for LLM reinforcement learning that uses a small, trusted validation set to prioritize training problems whose policy gradients align with validation gradients, yielding an adaptive curriculum. We evaluate GradAlign across three challenging data regimes: unreliable reward signals, distribution imbalance, and low-utility training corpus, showing that GradAlign consistently outperforms existing baselines, underscoring the importance of directional gradient signals in navigating non-stationary policy optimization and yielding more stable training and improved final performance. We release our implementation at https://github.com/StigLidu/GradAlign
title GradAlign: Gradient-Aligned Data Selection for LLM Reinforcement Learning
topic Machine Learning
Artificial Intelligence
Computation and Language
url https://arxiv.org/abs/2602.21492