Understanding the Difficulty of Low-Precision Post-Training Quantization for LLMs

Fuente: arXiv
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Autores principales: Xu, Zifei, Sharify, Sayeh, Yazar, Wanzin, Webb, Tristan, Wang, Xin
Formato: Preprint
Publicado: 2024
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author Xu, Zifei
Sharify, Sayeh
Yazar, Wanzin
Webb, Tristan
Wang, Xin
author_facet Xu, Zifei
Sharify, Sayeh
Yazar, Wanzin
Webb, Tristan
Wang, Xin
contents Large language models of high parameter counts are computationally expensive, yet can be made much more efficient by compressing their weights to very low numerical precision. This can be achieved either through post-training quantization by minimizing local, layer-wise quantization errors, or through quantization-aware fine-tuning by minimizing the global loss function. In this study, we discovered that, under the same data constraint, the former approach nearly always fared worse than the latter, a phenomenon particularly prominent when the numerical precision is very low. We further showed that this difficulty of post-training quantization arose from stark misalignment between optimization of the local and global objective functions. Our findings explains limited utility in minimization of local quantization error and the importance of direct quantization-aware fine-tuning, in the regime of large models at very low precision.
format Preprint
id arxiv_https___arxiv_org_abs_2410_14570
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Understanding the Difficulty of Low-Precision Post-Training Quantization for LLMs
Xu, Zifei
Sharify, Sayeh
Yazar, Wanzin
Webb, Tristan
Wang, Xin
Machine Learning
Large language models of high parameter counts are computationally expensive, yet can be made much more efficient by compressing their weights to very low numerical precision. This can be achieved either through post-training quantization by minimizing local, layer-wise quantization errors, or through quantization-aware fine-tuning by minimizing the global loss function. In this study, we discovered that, under the same data constraint, the former approach nearly always fared worse than the latter, a phenomenon particularly prominent when the numerical precision is very low. We further showed that this difficulty of post-training quantization arose from stark misalignment between optimization of the local and global objective functions. Our findings explains limited utility in minimization of local quantization error and the importance of direct quantization-aware fine-tuning, in the regime of large models at very low precision.
title Understanding the Difficulty of Low-Precision Post-Training Quantization for LLMs
topic Machine Learning
url https://arxiv.org/abs/2410.14570