Stochastic Spatial Routing for Reconfigurable Networks
FPGA placement and routing is time consuming, often serving as the major obstacle inhibiting a fast edit-compile-test loop in prototyping and development and the major obstacle preventing late-bound hardware and design mapping for reconfigurable systems. We introduce a stochastic search scheme which can achieve comparable route quality to traditional, software-based routers while being amenable to parallel, spatial implementation. We quantify the quality and performance of this route scheme using the Toronto Place-and-Route Challenge benchmarks. We sketch hardware implementations ranging from a minimal hardware-search assistance scheme which provides two orders of magnitude speedup, to FPGA-based schemes which provide greater speedup, to full hardware schemes which provide over three orders of magnitude routing acceleration. For coarse-grained devices with wide-word datapaths, the area overhead for integrating this hardware support into the network can be below 30%; for conventional FPGAs, a collection of hundreds of FPGAs can be configured to route one FPGA rapidly. With parallel path searches, the time required for the spatial solution scales sublinearly in network size for the typical, limited-bisection networks used for practical reconfigurable systems.