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arXiv 2602.17835cs.LG
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保留影响的梯度基数据选择代理

Influence-Preserving Proxies for Gradient-Based Data Selection in LLM Fine-tuning

University of Illinois Urbana-Champaign(伊利诺伊大学厄巴纳-香槟分校)

Sirui Chen, Yunzhe Qi, Mengting Ai, Yifan Sun, Ruizhong Qiu, Jiaru Zou, Jingrui He

AI总结:

Iprox通过两阶段框架直接从目标模型生成保留影响的代理,有效提升LLM微调中基于梯度的数据选择效率。

摘要:

监督微调(SFT)严重依赖于选择对模型下游性能最有益的训练数据。基于梯度的数据选择方法,如TracIn和影响函数,利用影响来识别有用样本,但它们的计算成本较高,使它们在多十亿参数的大语言模型(LLMs)中难以使用。常见的替代方法是使用现成的小模型作为代理,但它们仍然不理想,因为它们的学习动态不明确,大小无法灵活调整,且无法在基于梯度的影响估计方面进一步与目标模型对齐。为了解决这些挑战,我们介绍了Iprox,一个两阶段框架,它直接从目标模型中推导出保留影响的代理。它首先应用低秩压缩阶段以保留目标模型的影响信息,然后进行对齐阶段以对齐模型梯度和logits,从而构建出可以灵活控制计算成本同时保留目标模型影响的代理。在多样化的LLM家族和评估任务上的实验结果表明,Iprox在很大程度上优于现成的代理和基线方法。在Qwen3-4B上,使用Iprox构建的1.5B代理表现优于1.7B的现成代理。值得注意的是,在Llama3.2上,Iprox在减少计算成本超过一半的情况下,比基线方法表现更好。这些结果表明,Iprox提供了有效的保留影响的代理,使基于梯度的数据选择在LLMs中更具可扩展性。

英文摘要:

Supervised fine-tuning (SFT) relies critically on selecting training data that most benefits a model's downstream performance. Gradient-based data selection methods such as TracIn and Influence Functions leverage influence to identify useful samples, but their computational cost scales poorly, making them impractical for multi-billion-parameter large language models (LLMs). A common alternative is to use off-the-shelf smaller models as proxies, but they remain suboptimal since their learning dynamics are unclear, their sizes cannot be flexibly adjusted, and they cannot be further aligned with the target model in terms of gradient-based influence estimation. To address these challenges, we introduce Iprox, a two-stage framework that derives influence-preserving proxies directly from the target model. It first applies a low-rank compression stage to preserve influence information of the target model, and then an aligning stage to align both model gradients and logits, thereby constructing proxies that flexibly control computational cost while retaining the target model's influence. Experimental results across diverse LLM families and evaluation tasks show that Iprox consistently outperforms off-the-shelf proxies and baseline methods. On Qwen3-4B, a 1.5B proxy constructed with Iprox achieves stronger performance than the larger 1.7B off-the-shelf proxy. Notably, on Llama3.2, Iprox achieves better performance than baselines while reducing computational cost by more than half relative to the full 3B model. These results show that Iprox provides effective influence-preserving proxies, making gradient-based data selection more scalable for LLMs.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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