ESSPER: Elastic and Scalable FPGA-Cluster System for High-Performance Reconfigurable Computing with Supercomputer Fugaku.

FPGA clusters have yet to be a mainstream of HPC, even for accelerators, and several challenges exist in their architecture and system organization. This work presents ESSPER, a flexible and scalable FPGA cluster prototype system for reconfigurable HPC to meet the concept of customizability, scalability, and interoperability with existing HPC systems. Based on our classification of FPGA cluster architectures, we propose a new category of FPGA clusters with a host-FPGA bridging network using software-bridged APIs for the use of remote FPGAs. We have designed, implemented, verified, and demonstrated a proof-of-concept system of ESSPER, as a functional extension of the supercomputer Fugaku.