Comparison of direct and switch-based inter-FPGA routing interconnect for multi-FPGA systems

Abstract

Prototyping using multi-FPGA systems offers significant advantages over simulation and emulation based pre-silicon verification techniques in terms of performance and real world testing experience. Inter-FPGA routing interconnect and the quality of associated tool play a very important role in the performance of final prototyped design. In this work, we present a detailed comparison between four inter-FPGA interconnect routing topologies. We present a generic inter-FPA routing tool and for each topology, ten large benchmarks are prototyped on four different FPGA boards. Experimental results show that interconnect topology using a hybrid combination of two and multipoint tracks gives best results for smaller FPGA boards while topology using hybrid combination of switch-based and direct multi point tracks gives best frequency results for large FPGA boards and this frequency gain increases with increase in the number of FPGAs on board. We also perform execution time comparison between four interconnect topologies and the topology using direct two point connections only gives the best overall execution results. This topology, on average, requires 12%, 82%, and 70% less execution time as compared to other interconnect topologies under consideration.