Hardware and Software Co-optimization of Convolutional and Self-attention Combined Model Based on FPGA

Abstract

Since Transformer was proposed, the self-attention mechanism has been widely used. Some studies have tried to apply the self-attention mechanism to the field of computer vision CV. However, since self-attention lacks some inductive biases inherent to CNNs, it cannot achieve good generalization in the case of insufficient data. To solve this problem, researchers have proposed to combine the convolution module with the self-attention mechanism module to complement the inductive bias lacking by the self-attention mechanism. Many models based on this idea have been generated with good results. However, traditional central processor architectures cannot take good advantage of the parallel nature of these models. Among various computing platforms, FPGA becomes a suitable solution for algorithm acceleration with its high parallelism. At the same time, we note that the combined modules of convolution and self-attention have not received enough attention in terms of acceleration. Therefore, customizing computational units using FPGAs to improve model parallelism is a feasible solution. In this paper, we optimize the parallelism of the combined model of convolution and self-attention, and design algorithm optimization for two of the most complex generic nonlinear functions from the perspective of hardware-software co-optimization to further reduce the hardware complexity and the latency of the whole system, and design the corresponding hardware modules. The design is coded in HDL, a hardware description language, and simulated on a Xilinx FPGA. The experimental results show that the hardware resource consumption of the ZCU216 FPGA-based design is greatly reduced compared to the conventional design, while the throughput is increased by 8.82$\times$ and 1.23$\times$ compared to the CPU and GPU, respectively.