GPTAQ: Efficient Finetuning-Free Quantization for Asymmetric Calibration

Fuente: arXiv
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Main Authors: Li, Yuhang, Yin, Ruokai, Lee, Donghyun, Xiao, Shiting, Panda, Priyadarshini
Format: Preprint
Published: 2025
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author Li, Yuhang
Yin, Ruokai
Lee, Donghyun
Xiao, Shiting
Panda, Priyadarshini
author_facet Li, Yuhang
Yin, Ruokai
Lee, Donghyun
Xiao, Shiting
Panda, Priyadarshini
contents We introduce GPTAQ, a novel finetuning-free quantization method for compressing large-scale transformer architectures. Unlike the previous GPTQ method, which independently calibrates each layer, we always match the quantized layer's output to the exact output in the full-precision model, resulting in a scheme that we call asymmetric calibration. Such a scheme can effectively reduce the quantization error accumulated in previous layers. We analyze this problem using optimal brain compression to derive a close-formed solution. The new solution explicitly minimizes the quantization error as well as the accumulated asymmetry error. Furthermore, we utilize various techniques to parallelize the solution calculation, including channel parallelization, neuron decomposition, and Cholesky reformulation for matrix fusion. As a result, GPTAQ is easy to implement, simply using 20 more lines of code than GPTQ but improving its performance under low-bit quantization. Remarkably, on a single GPU, we quantize a 405B language transformer as well as EVA-02, the rank first vision transformer that achieves 90% pretraining Imagenet accuracy. Code is available at Github.
format Preprint
id arxiv_https___arxiv_org_abs_2504_02692
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle GPTAQ: Efficient Finetuning-Free Quantization for Asymmetric Calibration
Li, Yuhang
Yin, Ruokai
Lee, Donghyun
Xiao, Shiting
Panda, Priyadarshini
Machine Learning
We introduce GPTAQ, a novel finetuning-free quantization method for compressing large-scale transformer architectures. Unlike the previous GPTQ method, which independently calibrates each layer, we always match the quantized layer's output to the exact output in the full-precision model, resulting in a scheme that we call asymmetric calibration. Such a scheme can effectively reduce the quantization error accumulated in previous layers. We analyze this problem using optimal brain compression to derive a close-formed solution. The new solution explicitly minimizes the quantization error as well as the accumulated asymmetry error. Furthermore, we utilize various techniques to parallelize the solution calculation, including channel parallelization, neuron decomposition, and Cholesky reformulation for matrix fusion. As a result, GPTAQ is easy to implement, simply using 20 more lines of code than GPTQ but improving its performance under low-bit quantization. Remarkably, on a single GPU, we quantize a 405B language transformer as well as EVA-02, the rank first vision transformer that achieves 90% pretraining Imagenet accuracy. Code is available at Github.
title GPTAQ: Efficient Finetuning-Free Quantization for Asymmetric Calibration
topic Machine Learning
url https://arxiv.org/abs/2504.02692