arXiv:2605.06733cs.LGcs.AI2026-05被引 1

提出GLoRA,让联邦LoRA在异构环境下更高效准确地聚合模型更新。

Beyond Factor Aggregation: Gauge-Aware Low-Rank Server Representations for Federated LoRA

  • 不直接平均原始因子,而是通过投影估计共享更新子空间
  • 在多个数据/资源/任务异构场景下性能优于基线方法
  • 支持不同客户端的低秩适配器动态生成,无需重建全量参数

联邦LoRA可在去中心化数据和有限客户端资源下实现大模型的参数高效微调。然而,直接平均LoRA因子存在表示依赖问题:相同内在更新有无限种等价分解方式,因子级聚合会因坐标选择而改变,但底层更新不变,这导致现有联邦LoRA聚合规则存在语义错配。本文提出新型的GLoRA,采用对称感知的服务器表示机制。不直接聚合原始因子,而是从客户端投影中估计共识更新子空间,并在共享参考坐标系中聚合客户端更新,从而以低秩形式完整表达语义上的更新聚合。为支持异构客户端能力,GLoRA进一步提供秩兼容的读出机制,可从同一服务器状态实例化不同秩的适配器,无需密集更新重构。在GLUE和SuperNI数据集上的实验表明,即使在数据、资源、任务异构性以及稀疏参与、更大主干模型、未见任务评估等复杂条件下,GLoRA始终优于基线方法。同时实现了良好的效率-性能权衡,表明有效的联邦LoRA不仅需平均低秩因子,还需定义具有语义意义的服务器端聚合表示。

原文摘要 · Abstract (English)

Federated LoRA enables parameter-efficient adaptation of large language models under decentralized data and limited client resources.However, directly averaging LoRA factors is representation-dependent: the same intrinsic update admits infinitely many gauge-equivalent factorizations, so factor-level aggregation can change under arbitrary coordinate choices while the underlying update remains unchanged. This reveals a semantic mismatch in existing federated LoRA aggregation rules. We propose \textbf{GLoRA}, a gauge-aware server representation for federated LoRA.Instead of aggregating raw factors, GLoRA estimates a consensus update subspace from client projectors and aggregates client updates in shared reference coordinates, thereby representing semantic update aggregation entirely in low-rank form. To support heterogeneous client capacities, GLoRA further provides a rank-compatible readout that instantiates adapters of different ranks from the same server state without dense update reconstruction. Experiments on GLUE and SuperNI show that GLoRA consistently outperforms federated LoRA baselines under data, resource, and task heterogeneity, including heterogeneous client ranks, sparse participation, larger backbones, and unseen-task evaluation. GLoRA also achieves a favorable efficiency--performance trade-off, suggesting that effective federated LoRA requires not merely averaging low-rank factors, but defining a semantically meaningful server-side representation for aggregation.

联邦学习低秩适配模型聚合LoRA

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