Coarse-grain reconfigurable systems offer high performance and energy-efficiency, provided an efficient run-time reconfiguration mechanism is available. Using an embedded software vantage point, we define three levels of reconfigurability for such systems, each with a different degree of coupling between embedded software and reconfigurable hardware. We classify reconfigurable systems starting with tightly-coupled coprocessors and evolving to processor networks. This results in a gradual increase of energy-efficiency when compared to software-only systems, at the cost of increasing programming complexity.

Using several sample applications including signal-, crypto-, and network-processing acceleration units, we demonstrate energy-efficiency improvements of 12 times over software for tightly-coupled systems up to 84 times for network-on-chip systems.