Exploiting multiple switch libraries in topology synthesis of on-chip interconnection network

On-chip interconnection network is a crucial design component in high-performance System-on-Chips (SoCs). Many of previous works have focused on the automation of its topology design, since the topology largely determines its overall performance. For this purpose, they mostly require a switch library which includes all possible switch configurations (e.g. the number of in/output ports and data width) with their implementation costs such as delay, area, and power. More precisely, they characterize the switches by synthesizing them with a common design objective (e.g. minimizing area) and common design constraints for a given gate-level design library. The implementation costs are used in evaluating the topologies throughout the topology synthesis. The major drawback of single switch library approach is that it forces the topology synthesis methods to search the best topology with the assumption that all the switches comprising a topology will be implemented (synthesized) with a common design objective and common design constraints. Such assumption prevents them from exploring diverse combinations of the switches for a topology from the implementation perspective. To tackle this issue, we propose a topology synthesis method with multiple switch libraries, where the switch libraries are prepared with different design objectives and design constraints. The experimental results show that the power consumption and the area of optimal topologies can be saved by up to 67.1% and 27.2%, respectively, by the proposed method with negligible synthesis time overhead.