OASIS: Online Activation Subspace Learning for Memory-Efficient Training

Fuente: arXiv
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Auteurs principaux: Choudhary, Sakshi, Saxena, Utkarsh, Roy, Kaushik
Format: Preprint
Publié: 2026
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author Choudhary, Sakshi
Saxena, Utkarsh
Roy, Kaushik
author_facet Choudhary, Sakshi
Saxena, Utkarsh
Roy, Kaushik
contents Training large language models (LLMs) is constrained by memory requirements, with activations accounting for a substantial fraction of the total footprint. Existing approaches reduce memory using low-rank weight parameterizations or low-rank gradient subspaces for optimizer states, while activation memory is addressed through architectural modifications or compression schemes based on periodically updated projections. We propose OASIS, an online activation subspace learning algorithm for memory-efficient training that tracks and continuously updates a low-dimensional activation subspace during training. Intermediate activations are projected onto this evolving subspace, reducing memory without modifying forward-pass computations. The evolving activation subspace induces low-rank gradient representations, enabling both gradients and optimizer states to be maintained directly in this subspace, while a projection-aware optimizer consistently transports optimizer states across subspace updates for stable training. Across various finetuning and pretraining tasks, OASIS achieves up to $2\times$ lower peak memory than full fine-tuning while matching its performance and outperforming prior low-rank methods.
format Preprint
id arxiv_https___arxiv_org_abs_2604_09406
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle OASIS: Online Activation Subspace Learning for Memory-Efficient Training
Choudhary, Sakshi
Saxena, Utkarsh
Roy, Kaushik
Machine Learning
Training large language models (LLMs) is constrained by memory requirements, with activations accounting for a substantial fraction of the total footprint. Existing approaches reduce memory using low-rank weight parameterizations or low-rank gradient subspaces for optimizer states, while activation memory is addressed through architectural modifications or compression schemes based on periodically updated projections. We propose OASIS, an online activation subspace learning algorithm for memory-efficient training that tracks and continuously updates a low-dimensional activation subspace during training. Intermediate activations are projected onto this evolving subspace, reducing memory without modifying forward-pass computations. The evolving activation subspace induces low-rank gradient representations, enabling both gradients and optimizer states to be maintained directly in this subspace, while a projection-aware optimizer consistently transports optimizer states across subspace updates for stable training. Across various finetuning and pretraining tasks, OASIS achieves up to $2\times$ lower peak memory than full fine-tuning while matching its performance and outperforming prior low-rank methods.
title OASIS: Online Activation Subspace Learning for Memory-Efficient Training
topic Machine Learning
url https://arxiv.org/abs/2604.09406