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Main Authors: Ding, Xinyu, Liu, Bangtian, Liao, Siyu, Wang, Zhongfeng
Format: Preprint
Published: 2025
Subjects:
Online Access:https://arxiv.org/abs/2511.01385
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author Ding, Xinyu
Liu, Bangtian
Liao, Siyu
Wang, Zhongfeng
author_facet Ding, Xinyu
Liu, Bangtian
Liao, Siyu
Wang, Zhongfeng
contents Fast Fourier Transforms (FFT) are widely used to reduce memory and computational costs in deep learning. However, existing implementations, including standard FFT and real FFT (rFFT), cannot achieve true in-place computation. In particular, rFFT maps an input of size n to a complex output of size n/2+1, causing dimensional mismatch and requiring additional memory allocation. We propose the first real-domain, fully in-place FFT framework (rdFFT) that preserves input-output memory space consistency. By leveraging butterfly operation symmetry and conjugate properties in the frequency domain, we design an implicit complex encoding scheme that eliminates intermediate cache usage entirely. Experiments on multiple natural language understanding tasks demonstrate the method effectiveness in reducing training memory cost, offering a promising direction for frequency-domain lightweight adaptation.
format Preprint
id arxiv_https___arxiv_org_abs_2511_01385
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Memory-Efficient Training with In-Place FFT Implementation
Ding, Xinyu
Liu, Bangtian
Liao, Siyu
Wang, Zhongfeng
Machine Learning
I.2.6; G.1.2; D.1.3
Fast Fourier Transforms (FFT) are widely used to reduce memory and computational costs in deep learning. However, existing implementations, including standard FFT and real FFT (rFFT), cannot achieve true in-place computation. In particular, rFFT maps an input of size n to a complex output of size n/2+1, causing dimensional mismatch and requiring additional memory allocation. We propose the first real-domain, fully in-place FFT framework (rdFFT) that preserves input-output memory space consistency. By leveraging butterfly operation symmetry and conjugate properties in the frequency domain, we design an implicit complex encoding scheme that eliminates intermediate cache usage entirely. Experiments on multiple natural language understanding tasks demonstrate the method effectiveness in reducing training memory cost, offering a promising direction for frequency-domain lightweight adaptation.
title Memory-Efficient Training with In-Place FFT Implementation
topic Machine Learning
I.2.6; G.1.2; D.1.3
url https://arxiv.org/abs/2511.01385