BBAL: A Bidirectional Block Floating Point-Based Quantisation Accelerator for Large Language Models

Fuente: arXiv
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Main Authors: Han, Xiaomeng, Cheng, Yuan, Wang, Jing, Lu, Junyang, Wang, Hui, Zhang, X. x., Xu, Ning, Yang, Dawei, Jiang, Zhe
Format: Preprint
Published: 2025
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author Han, Xiaomeng
Cheng, Yuan
Wang, Jing
Lu, Junyang
Wang, Hui
Zhang, X. x.
Xu, Ning
Yang, Dawei
Jiang, Zhe
author_facet Han, Xiaomeng
Cheng, Yuan
Wang, Jing
Lu, Junyang
Wang, Hui
Zhang, X. x.
Xu, Ning
Yang, Dawei
Jiang, Zhe
contents Large language models (LLMs), with their billions of parameters, pose substantial challenges for deployment on edge devices, straining both memory capacity and computational resources. Block Floating Point (BFP) quantisation reduces memory and computational overhead by converting high-overhead floating point operations into low-bit fixed point operations. However, BFP requires aligning all data to the maximum exponent, which causes loss of small and moderate values, resulting in quantisation error and degradation in the accuracy of LLMs. To address this issue, we propose a Bidirectional Block Floating Point (BBFP) data format, which reduces the probability of selecting the maximum as shared exponent, thereby reducing quantisation error. By utilizing the features in BBFP, we present a full-stack Bidirectional Block Floating Point-Based Quantisation Accelerator for LLMs (BBAL), primarily comprising a processing element array based on BBFP, paired with proposed cost-effective nonlinear computation unit. Experimental results show BBAL achieves a 22% improvement in accuracy compared to an outlier-aware accelerator at similar efficiency, and a 40% efficiency improvement over a BFP-based accelerator at similar accuracy.
format Preprint
id arxiv_https___arxiv_org_abs_2504_15721
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle BBAL: A Bidirectional Block Floating Point-Based Quantisation Accelerator for Large Language Models
Han, Xiaomeng
Cheng, Yuan
Wang, Jing
Lu, Junyang
Wang, Hui
Zhang, X. x.
Xu, Ning
Yang, Dawei
Jiang, Zhe
Hardware Architecture
Large language models (LLMs), with their billions of parameters, pose substantial challenges for deployment on edge devices, straining both memory capacity and computational resources. Block Floating Point (BFP) quantisation reduces memory and computational overhead by converting high-overhead floating point operations into low-bit fixed point operations. However, BFP requires aligning all data to the maximum exponent, which causes loss of small and moderate values, resulting in quantisation error and degradation in the accuracy of LLMs. To address this issue, we propose a Bidirectional Block Floating Point (BBFP) data format, which reduces the probability of selecting the maximum as shared exponent, thereby reducing quantisation error. By utilizing the features in BBFP, we present a full-stack Bidirectional Block Floating Point-Based Quantisation Accelerator for LLMs (BBAL), primarily comprising a processing element array based on BBFP, paired with proposed cost-effective nonlinear computation unit. Experimental results show BBAL achieves a 22% improvement in accuracy compared to an outlier-aware accelerator at similar efficiency, and a 40% efficiency improvement over a BFP-based accelerator at similar accuracy.
title BBAL: A Bidirectional Block Floating Point-Based Quantisation Accelerator for Large Language Models
topic Hardware Architecture
url https://arxiv.org/abs/2504.15721