Locally Estimated Global Perturbations are Better than Local Perturbations for Federated Sharpness-aware Minimization

Fuente: arXiv
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Main Authors: Fan, Ziqing, Hu, Shengchao, Yao, Jiangchao, Niu, Gang, Zhang, Ya, Sugiyama, Masashi, Wang, Yanfeng
Format: Preprint
Published: 2024
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author Fan, Ziqing
Hu, Shengchao
Yao, Jiangchao
Niu, Gang
Zhang, Ya
Sugiyama, Masashi
Wang, Yanfeng
author_facet Fan, Ziqing
Hu, Shengchao
Yao, Jiangchao
Niu, Gang
Zhang, Ya
Sugiyama, Masashi
Wang, Yanfeng
contents In federated learning (FL), the multi-step update and data heterogeneity among clients often lead to a loss landscape with sharper minima, degenerating the performance of the resulted global model. Prevalent federated approaches incorporate sharpness-aware minimization (SAM) into local training to mitigate this problem. However, the local loss landscapes may not accurately reflect the flatness of global loss landscape in heterogeneous environments; as a result, minimizing local sharpness and calculating perturbations on client data might not align the efficacy of SAM in FL with centralized training. To overcome this challenge, we propose FedLESAM, a novel algorithm that locally estimates the direction of global perturbation on client side as the difference between global models received in the previous active and current rounds. Besides the improved quality, FedLESAM also speed up federated SAM-based approaches since it only performs once backpropagation in each iteration. Theoretically, we prove a slightly tighter bound than its original FedSAM by ensuring consistent perturbation. Empirically, we conduct comprehensive experiments on four federated benchmark datasets under three partition strategies to demonstrate the superior performance and efficiency of FedLESAM.
format Preprint
id arxiv_https___arxiv_org_abs_2405_18890
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Locally Estimated Global Perturbations are Better than Local Perturbations for Federated Sharpness-aware Minimization
Fan, Ziqing
Hu, Shengchao
Yao, Jiangchao
Niu, Gang
Zhang, Ya
Sugiyama, Masashi
Wang, Yanfeng
Machine Learning
Distributed, Parallel, and Cluster Computing
In federated learning (FL), the multi-step update and data heterogeneity among clients often lead to a loss landscape with sharper minima, degenerating the performance of the resulted global model. Prevalent federated approaches incorporate sharpness-aware minimization (SAM) into local training to mitigate this problem. However, the local loss landscapes may not accurately reflect the flatness of global loss landscape in heterogeneous environments; as a result, minimizing local sharpness and calculating perturbations on client data might not align the efficacy of SAM in FL with centralized training. To overcome this challenge, we propose FedLESAM, a novel algorithm that locally estimates the direction of global perturbation on client side as the difference between global models received in the previous active and current rounds. Besides the improved quality, FedLESAM also speed up federated SAM-based approaches since it only performs once backpropagation in each iteration. Theoretically, we prove a slightly tighter bound than its original FedSAM by ensuring consistent perturbation. Empirically, we conduct comprehensive experiments on four federated benchmark datasets under three partition strategies to demonstrate the superior performance and efficiency of FedLESAM.
title Locally Estimated Global Perturbations are Better than Local Perturbations for Federated Sharpness-aware Minimization
topic Machine Learning
Distributed, Parallel, and Cluster Computing
url https://arxiv.org/abs/2405.18890