TaRA让LoRA初始化更准,提升微调效果
TaRA: Training-Aware Low-Rank Adaptation Initialization
- 根据全模型梯度设计低秩矩阵初始值
- 训练初期梯度逼近度显著提升,性能更优
- 适合追求高效微调的AI研究者与工程师
低秩适应(LoRA)已成为参数高效微调(PEFT)的主流方法,但其性能对初始化高度敏感,源于低秩分解带来的信息瓶颈。现有方法通过利用预训练权重、激活或梯度的主成分来构建高质量的LoRA初始值,但未直接考虑全模型的训练动态。本文提出训练感知的低秩适应初始化(TaRA),使低秩因子引起的梯度尽可能逼近对应全秩权重矩阵的梯度。基于数学推导,TaRA在训练初期显著提升梯度保真度,且计算开销可忽略。在多种复杂微调任务中,TaRA持续优于现有最先进方法,提供一种简单、稳健且可扩展的有效LoRA初始化方案。
原文摘要 · Abstract (English)
Low-Rank Adaptation (LoRA) has become a de facto standard for parameter-efficient fine-tuning (PEFT), yet its performance is highly sensitive to initialization due to the information bottleneck imposed by low-rank decomposition. Existing approaches attempt to construct high-quality LoRA initializations by exploiting principal components of pretrained weights, activations, or gradients. However, these methods do not directly account for the training dynamics of the full-rank model. In this paper, we propose Training-aware Low-Rank Adaptation Initialization (TaRA), a method that initializes LoRA such that the gradients induced by the low-rank factors closely approximate the gradient of the corresponding full-rank weight matrix. Derived from a mathematical formulation, TaRA improves gradient fidelity at the start of training while introducing negligible computational overhead. Across diverse and challenging fine-tuning tasks, TaRA consistently outperforms prior state-of-the-art methods, establishing a simple, robust, and scalable solution for effective LoRA initialization.
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