ParaDiMe: A Distributed Memory FPGA Router Based on Speculative Parallelism and Path Encoding

Abstract

The increase in speed and capacity of FPGAs is faster than the development of effective design tools to fully utilize it, and routing of nets remains as one of the most time-consuming stages of the FPGA design flow. While existing works have proposed methods of accelerating routing through parallelization, they are limited by the memory architecture of the system that they target. In this paper, we propose a distributed memory parallel FPGA router called ParaDiMe to address the limitations of existing works. ParaDiMe speculatively routes net in parallel and dynamically detects the need to reduce the number of active processes in order to achieve convergence. In addition, the synchronization overhead in ParaDiMe is significantly reduced through a careful design of the messaging protocol where paths to sinks are encoded in a space-efficient manner. Moreover, the frequency of synchronization is tuned to ensure convergence while minimizing the communication overhead. Compared to VTR, ParaDiMe achieves an average speedup of 19.8X with 32 processes while producing similar quality of results.