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arXiv 2603.08014cs.LGcs.AI
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FedMomentum: 在联邦微调中保持LoRA训练动量

FedMomentum: Preserving LoRA Training Momentum in Federated Fine-Tuning

Shanghai Jiao Tong University(上海交通大学);Queen's University Belfast(女王大学贝尔法斯特分校);Stevens Institute of Technology(史蒂文斯理工学院);Purdue University(普渡大学);Rice University(里奇大学)

Peishen Yan, Yang Hua, Hao Wang, Jiaru Zhang, Xiaoyu Wu, Tao Song, Haibing Guan

AI总结:

FedMomentum通过奇异值分解实现结构化且动量保持的LoRA聚合,提升联邦微调中的收敛速度和准确率。

摘要:

大型语言模型(LLMs)的联邦微调结合低秩适应(LoRA)提供了一种通信高效且隐私保护的解决方案,用于任务特定的适应。简单地聚合LoRA模块由于数学不正确性,在独立平均下采样和上采样矩阵时引入噪声。然而,现有的无噪声聚合策略不可避免地会牺牲LoRA的结构表达性,限制其保留客户端特定适应的能力,要么通过不恰当地重建低秩结构,要么通过排除部分可训练组件。我们将其问题定义为动量损失,其中LoRA更新在轮次中无法有效积累,导致收敛速度慢和性能欠佳。为了解决这一问题,我们提出了FedMomentum,一种新的框架,通过奇异值分解(SVD)实现结构化且动量保持的LoRA聚合。具体来说,在以数学正确的方式聚合低秩更新后,FedMomentum应用SVD提取主导组件,这些组件捕捉了主要的更新方向。这些组件用于重建相同秩的LoRA模块,而残余组件可以保留并在之后合并到骨干网络中,以保持语义信息并确保鲁棒性。在多个任务上的广泛实验表明,FedMomentum在收敛速度和最终准确率上一致优于先前的最先进方法。

英文摘要:

Federated fine-tuning of large language models (LLMs) with low-rank adaptation (LoRA) offers a communication-efficient and privacy-preserving solution for task-specific adaptation. Naive aggregation of LoRA modules introduces noise due to mathematical incorrectness when averaging the downsampling and upsampling matrices independently. However, existing noise-free aggregation strategies inevitably compromise the structural expressiveness of LoRA, limiting its ability to retain client-specific adaptations by either improperly reconstructing the low-rank structure or excluding partially trainable components. We identify this problem as loss of training momentum, where LoRA updates fail to accumulate effectively across rounds, resulting in slower convergence and suboptimal performance. To address this, we propose FedMomentum, a novel framework that enables structured and momentum-preserving LoRA aggregation via singular value decomposition (SVD). Specifically, after aggregating low-rank updates in a mathematically correct manner, FedMomentum applies SVD to extract the dominant components that capture the main update directions. These components are used to reconstruct the LoRA modules with the same rank, while residual components can be retained and later merged into the backbone to preserve semantic information and ensure robustness. Extensive experiments across multiple tasks demonstrate that FedMomentum consistently outperforms prior state-of-the-art methods in convergence speed and final accuracy.

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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