LocusRoute: a parallel global router for standard cells

Abstract

A fast and easily parallelizable global routing algorithm for standard cells and its parallel implementation is presented. LocusRoute is meant to be used as the cost function for a placement algorithm and so this context constrains the structure of the global routing algorithm and its parallel implementation. The router is based on enumerating a subset of all two-bend routes between two points, and results in 16% to 37% fewer total number of tracks than the TimberWolf global router for standard cells [Sech85]. It is comparable in quality to a maze router and an industrial router, but is factor of 10 times or more faster. Three approaches to parallelizing the router are implemented: wire-by-wire parallelism, segment-by-segment and route-by-route. Two of these approaches achieve significant speedup - route-by-route achieves up to 4.6 using eight processors, and wire-by-wire achieves from 5.8 to 7.6 on eight processors.