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arXiv 2511.07971cs.LG

低秩曲率用于大语言模型微调中的零阶优化

Low-Rank Curvature for Zeroth-Order Optimization in LLM Fine-Tuning

University of Wisconsin – Madison(威斯康星大学麦迪逊分校);University of Georgia(佐治亚大学);Hanyang University(翰阳大学)

Hyunseok Seung, Jaewoo Lee, Hyunsuk Ko

AI总结:

提出LOREN方法,通过低秩块对角预条件器捕捉曲率并利用REINFORCE留一法梯度估计器降低方差,在LLM微调中实现更高精度和更快收敛,同时峰值内存使用降低27.3%。

摘要:

我们引入了LOREN,一种用于微调大型语言模型(LLM)的曲率感知零阶(ZO)优化方法。现有的ZO方法通过随机扰动的有限差分估计梯度,常常遭受高方差和次优搜索方向的问题。我们的方法通过以下方式解决这些挑战:(i)将梯度预条件问题重新表述为自适应估计用于梯度估计的各向异性扰动分布的问题,(ii)通过自然进化策略框架,使用低秩块对角预条件器捕捉曲率,以及(iii)应用REINFORCE留一法(RLOO)梯度估计器来降低方差。在标准LLM基准上的实验表明,我们的方法通过实现更高的精度和更快的收敛,优于最先进的ZO方法,同时与MeZO-Adam相比,峰值内存使用减少了高达27.3%。

英文摘要:

We introduce LOREN, a curvature-aware zeroth-order (ZO) optimization method for fine-tuning large language models (LLMs). Existing ZO methods, which estimate gradients via finite differences using random perturbations, often suffer from high variance and suboptimal search directions. Our approach addresses these challenges by: (i) reformulating the problem of gradient preconditioning as that of adaptively estimating an anisotropic perturbation distribution for gradient estimation, (ii) capturing curvature through a low-rank block diagonal preconditioner using the framework of natural evolution strategies, and (iii) applying a REINFORCE leave-one-out (RLOO) gradient estimator to reduce variance. Experiments on standard LLM benchmarks show that our method outperforms state-of-the-art ZO methods by achieving higher accuracy and faster convergence, while cutting peak memory usage by up to 27.3% compared with MeZO-Adam.

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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