Title
An Energy Efficient Accelerator for Bidirectional Recurrent Neural Networks (BiRNNs) Using Hybrid-Iterative Compression With Error Sensitivity
Abstract
Recurrent Neural Networks (RNNs) have been widely used in many sequential applications, such as machine translation, speech recognition and sentiment analysis. Long Term Short Term Memory (LSTM) and Gated Recurrent Unit (GRU) are widely used variants of RNN due to their effectiveness in overcoming gradient vanishing and exploding problems; however, compared to conventional RNN, their massive storage and computation requirements hinder their application. In addition, the recurrent structure of RNNs makes them prone to accumulate errors, resulting in a severe loss of accuracy. In this work, we propose a hybrid-iterative compression (HIC) algorithm for LSTM/GRU. By exploiting the error sensitivity of RNN, the gating units are divided into error-sensitive and error-insensitive groups, that are compressed using different algorithms. By using this approach, a 37.1×/32.3× compression ratio is achieved with negligible accuracy loss for LSTM/GRU. Further, an energy efficient accelerator for bidirectional RNNs is proposed. In this accelerator, the data flow of the matrix operation unit based on the block structure matrix (MOU-S) is improved through rearranging weights; the utilization of BRAM is improved through a fine-grained parallelism configuration of matrix-vector multiplications (MVMs). Meanwhile, the timing matching strategy alleviates the load-imbalance problem between MOU-S and the matrix operation unit based on top- k pruning (MOU-P). When running at 200MHz on Xilinx ADM-PCIE-7V3 FPGA, the proposed design achieves an improvement in energy efficiency in a range of 5%-237% for LSTM networks, and an improvement of 58% for GRU networks compared with state-of-the-art designs.
Year
DOI
Venue
2021
10.1109/TCSI.2021.3091318
IEEE Transactions on Circuits and Systems I: Regular Papers
Keywords
DocType
Volume
Recurrent neural network (RNN),neural network compression,FPGAs
Journal
68
Issue
ISSN
Citations 
9
1549-8328
1
PageRank 
References 
Authors
0.35
0
7
Name
Order
Citations
PageRank
Guocai Nan110.35
Zhengkuan Wang210.35
Chenghua Wang364.54
Bi Wu4176.61
Zhican Wang510.35
Weiqiang Liu6178.24
Fabrizio Lombardi75710.81