arXiv:2605.07850cs.CLcs.AI2026-05

提出可动态调整秩的LoRA框架,提升大模型微调效率与精度。

MatryoshkaLoRA: Learning Accurate Hierarchical Low-Rank Representations for LLM Fine-Tuning

  • 通过插入可学习对角矩阵,实现低秩表示的层次化自适应。
  • 在多个数据集上优于现有方法,在不同秩下均保持高准确率。
  • 适合需要高效微调大模型的研究者和工程实践者。

随着深度学习模型规模达数十亿参数,微调的计算成本仍是部署的主要障碍。尽管低秩适配(LoRA)已成为参数高效微调的标准方法,但需预先设定静态秩 $r$,需通过大量网格搜索平衡效率与性能。现有自适应秩方法如 DyLoRA 通过训练中采样秩来缓解此问题,但在高秩时因梯度信号不一致导致性能欠佳,数据利用效率低。本文提出 MatryoshkaLoRA,一种受俄罗斯套娃启发的通用训练框架,通过在原有 LoRA 适配器间插入一个固定且精心设计的对角矩阵 $P$,按需缩放子秩。该简单修改使框架能仅通过调整 $P$ 恢复传统 LoRA 与 DyLoRA,确保所有子秩有效接收梯度信息。所提方法支持动态秩选择,精度损失极小。我们进一步提出面积-秩精度曲线(AURAC)以统一评估层级低秩适配器性能。实验表明,MatryoshkaLoRA 学习到的层次化低秩表示更准确,在各数据集上的精度-性能权衡显著优于已有方法。代码已开源:https://github.com/IST-DASLab/MatryoshkaLoRA。

原文摘要 · Abstract (English)

With the rise in scale for deep learning models to billions of parameters, the computational cost of fine-tuning remains a significant barrier to deployment. While Low-Rank Adaptation (LoRA) has become the standard for parameter-efficient fine-tuning, the need to set a predefined, static rank $r$ requires exhaustive grid searches to balance efficiency and performance. Existing rank-adaptive solutions such as DyLoRA mitigate this by sampling ranks during the training from a predefined distribution. However, they often yield sub-optimal results at higher ranks due to lack of consistent gradient signals across the full hierarchy of ranks, thus making these methods data-inefficient. In this paper, we propose MatryoshkaLoRA, a general, Matryoshka-inspired training framework for LoRA that learns accurate hierarchical low-rank representations by inserting a fixed, carefully crafted diagonal matrix $P$ between the existing LoRA adapters to scale their sub-ranks accordingly. By introducing this simple modification, our general framework recovers LoRA and DyLoRA only by changing $P$ and ensures all sub-ranks embed the available gradient information efficiently. Our MatryoshkaLoRA supports dynamic rank selection with minimal degradation in accuracy. We further propose Area Under the Rank Accuracy Curve (AURAC), a metric that consistently evaluates the performance of hierarchical low-rank adapters. Our results demonstrate that MatryoshkaLoRA learns more accurate hierarchical low-rank representations than prior rank-adaptive approaches and achieves superior accuracy-performance trade-offs across ranks on the evaluated datasets. Our code is available at https://github.com/IST-DASLab/MatryoshkaLoRA.

LoRA大模型微调低秩适配动态秩

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