PermLSTM: A High Energy-Efficiency LSTM Accelerator Architecture

Pruning and quantization are two commonly used approaches to accelerate the LSTM (Long Short-Term Memory) model. However, the traditional linear quantization usually suffers from the problem of gradient vanishing, and the existing pruning methods all have the problem of producing undesired irregular...

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Main Authors: Yong Zheng, Haigang Yang, Yiping Jia, Zhihong Huang
Format: Article
Language:English
Published: MDPI AG 2021-04-01
Series:Electronics
Subjects:
Online Access:https://www.mdpi.com/2079-9292/10/8/882
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author Yong Zheng
Haigang Yang
Yiping Jia
Zhihong Huang
author_facet Yong Zheng
Haigang Yang
Yiping Jia
Zhihong Huang
author_sort Yong Zheng
collection DOAJ
description Pruning and quantization are two commonly used approaches to accelerate the LSTM (Long Short-Term Memory) model. However, the traditional linear quantization usually suffers from the problem of gradient vanishing, and the existing pruning methods all have the problem of producing undesired irregular sparsity or large indexing overhead. To alleviate the problem of vanishing gradient, this work proposed a normalized linear quantization approach, which first normalize operands regionally and then quantize them in a local mix-max range. To overcome the problem of irregular sparsity and large indexing overhead, this work adopts the permuted block diagonal mask matrices to generate the sparse model. Due to the sparse model being highly regular, the position of non-zero weights can be obtained by a simple calculation, thus avoiding the large indexing overhead. Based on the sparse LSTM model generated from the permuted block diagonal mask matrices, this paper also proposed a high energy-efficiency accelerator, PermLSTM that comprehensively exploits the sparsity of weights, activations, and products regarding the matrix–vector multiplications, resulting in a 55.1% reduction in power consumption. The accelerator has been realized on Arria-10 FPGAs running at 150 MHz and achieved <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>2.19</mn><mo>×</mo></mrow></semantics></math></inline-formula>∼<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>24.4</mn><mo>×</mo></mrow></semantics></math></inline-formula> energy efficiency compared with the other FPGA-based LSTM accelerators previously reported.
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spelling doaj.art-4ee34c6481e7414697fc57ae1c605c352023-11-21T14:38:15ZengMDPI AGElectronics2079-92922021-04-0110888210.3390/electronics10080882PermLSTM: A High Energy-Efficiency LSTM Accelerator ArchitectureYong Zheng0Haigang Yang1Yiping Jia2Zhihong Huang3Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing 100094, ChinaAerospace Information Research Institute, Chinese Academy of Sciences, Beijing 100094, ChinaAerospace Information Research Institute, Chinese Academy of Sciences, Beijing 100094, ChinaAerospace Information Research Institute, Chinese Academy of Sciences, Beijing 100094, ChinaPruning and quantization are two commonly used approaches to accelerate the LSTM (Long Short-Term Memory) model. However, the traditional linear quantization usually suffers from the problem of gradient vanishing, and the existing pruning methods all have the problem of producing undesired irregular sparsity or large indexing overhead. To alleviate the problem of vanishing gradient, this work proposed a normalized linear quantization approach, which first normalize operands regionally and then quantize them in a local mix-max range. To overcome the problem of irregular sparsity and large indexing overhead, this work adopts the permuted block diagonal mask matrices to generate the sparse model. Due to the sparse model being highly regular, the position of non-zero weights can be obtained by a simple calculation, thus avoiding the large indexing overhead. Based on the sparse LSTM model generated from the permuted block diagonal mask matrices, this paper also proposed a high energy-efficiency accelerator, PermLSTM that comprehensively exploits the sparsity of weights, activations, and products regarding the matrix–vector multiplications, resulting in a 55.1% reduction in power consumption. The accelerator has been realized on Arria-10 FPGAs running at 150 MHz and achieved <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>2.19</mn><mo>×</mo></mrow></semantics></math></inline-formula>∼<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>24.4</mn><mo>×</mo></mrow></semantics></math></inline-formula> energy efficiency compared with the other FPGA-based LSTM accelerators previously reported.https://www.mdpi.com/2079-9292/10/8/882LSTMpruningquantizationsparse matrix–vector multiplication
spellingShingle Yong Zheng
Haigang Yang
Yiping Jia
Zhihong Huang
PermLSTM: A High Energy-Efficiency LSTM Accelerator Architecture
Electronics
LSTM
pruning
quantization
sparse matrix–vector multiplication
title PermLSTM: A High Energy-Efficiency LSTM Accelerator Architecture
title_full PermLSTM: A High Energy-Efficiency LSTM Accelerator Architecture
title_fullStr PermLSTM: A High Energy-Efficiency LSTM Accelerator Architecture
title_full_unstemmed PermLSTM: A High Energy-Efficiency LSTM Accelerator Architecture
title_short PermLSTM: A High Energy-Efficiency LSTM Accelerator Architecture
title_sort permlstm a high energy efficiency lstm accelerator architecture
topic LSTM
pruning
quantization
sparse matrix–vector multiplication
url https://www.mdpi.com/2079-9292/10/8/882
work_keys_str_mv AT yongzheng permlstmahighenergyefficiencylstmacceleratorarchitecture
AT haigangyang permlstmahighenergyefficiencylstmacceleratorarchitecture
AT yipingjia permlstmahighenergyefficiencylstmacceleratorarchitecture
AT zhihonghuang permlstmahighenergyefficiencylstmacceleratorarchitecture