Modeling and Exploration of Elastic CGRAs

Abstract

Elastic design concepts have the potential to bring multiple benefits to coarse-grained reconfigurable arrays (CGRAs) architecture, including the ability to interface with memories, having unknown latencies, incorporate run-time variable-latency processing elements, and ease the CGRA mapping challenges of scheduling, placement and routing. However, there are overheads in terms of power, performance and area (PPA) associated with the design and implementation of elastic circuits. In this paper, we quantify these overheads in the CGRA context by first extending an open-source CGRA modelling and exploration framework (CGRA-ME) [4] to allow elastic circuit primitives (e.g. fork, join, merge, diverge, etc.) to be used when composing/modelling a CGRA architecture. We then use this new capability to “elasticize” two widely studied CGRA architectures, ADRES [11] and HyCUBE [8]. The PPA of the elastic versions of the CGRAs are compared with their traditional statically scheduled counterparts. We also evaluate the PPA “cost” of several elastic-circuit design points, such as elastic buffer length and inclusion of merge and diverge components.