Greedy Low-Rank Gradient Compression for Distributed Learning with Convergence Guarantees

Fuente: arXiv
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Main Authors: Chen, Chuyan, He, Yutong, Li, Pengrui, Jia, Weichen, Yuan, Kun
Format: Preprint
Published: 2025
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author Chen, Chuyan
He, Yutong
Li, Pengrui
Jia, Weichen
Yuan, Kun
author_facet Chen, Chuyan
He, Yutong
Li, Pengrui
Jia, Weichen
Yuan, Kun
contents Distributed optimization is pivotal for large-scale signal processing and machine learning, yet communication overhead remains a major bottleneck. Low-rank gradient compression, in which the transmitted gradients are approximated by low-rank matrices to reduce communication, offers a promising remedy. Existing methods typically adopt either randomized or greedy compression strategies: randomized approaches project gradients onto randomly chosen subspaces, introducing high variance and degrading empirical performance; greedy methods select the most informative subspaces, achieving strong empirical results but lacking convergence guarantees. To address this gap, we propose GreedyLore--the first Greedy Low-Rank gradient compression algorithm for distributed learning with rigorous convergence guarantees. GreedyLore incorporates error feedback to correct the bias introduced by greedy compression and introduces a semi-lazy subspace update that ensures the compression operator remains contractive throughout all iterations. With these techniques, we prove that GreedyLore achieves a convergence rate of $\mathcal{O}(σ/\sqrt{NT} + 1/T)$ under standard optimizers such as MSGD and Adam--marking the first linear speedup convergence rate for low-rank gradient compression. Extensive experiments are conducted to validate our theoretical findings.
format Preprint
id arxiv_https___arxiv_org_abs_2507_08784
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Greedy Low-Rank Gradient Compression for Distributed Learning with Convergence Guarantees
Chen, Chuyan
He, Yutong
Li, Pengrui
Jia, Weichen
Yuan, Kun
Machine Learning
Optimization and Control
Distributed optimization is pivotal for large-scale signal processing and machine learning, yet communication overhead remains a major bottleneck. Low-rank gradient compression, in which the transmitted gradients are approximated by low-rank matrices to reduce communication, offers a promising remedy. Existing methods typically adopt either randomized or greedy compression strategies: randomized approaches project gradients onto randomly chosen subspaces, introducing high variance and degrading empirical performance; greedy methods select the most informative subspaces, achieving strong empirical results but lacking convergence guarantees. To address this gap, we propose GreedyLore--the first Greedy Low-Rank gradient compression algorithm for distributed learning with rigorous convergence guarantees. GreedyLore incorporates error feedback to correct the bias introduced by greedy compression and introduces a semi-lazy subspace update that ensures the compression operator remains contractive throughout all iterations. With these techniques, we prove that GreedyLore achieves a convergence rate of $\mathcal{O}(σ/\sqrt{NT} + 1/T)$ under standard optimizers such as MSGD and Adam--marking the first linear speedup convergence rate for low-rank gradient compression. Extensive experiments are conducted to validate our theoretical findings.
title Greedy Low-Rank Gradient Compression for Distributed Learning with Convergence Guarantees
topic Machine Learning
Optimization and Control
url https://arxiv.org/abs/2507.08784