A procedure for improving the distribution of congestion in global routing

Abstract

This work introduces a procedure which takes as input a global routing solution that is already improved for routability based on the traditional total overflow (TOF) metric, and then improves the distribution of congestion without increasing the TOF. Our router is able to significantly decrease the number of edges in undesirable ranges of congestion by optimizing a convex piece-wise linear penalty function. The penalties are flexible and may be specified by the user. In our experiments, using the already-optimized global routing solutions of the ISPD'11 benchmarks-mostly have 0 units of TOF-we show the number of edges which are utilized very close to capacity can be significantly reduced. This work is the first to explicitly target improving the distribution of edge congestion corresponding to an already-optimized global routing solution without sacrificing the TOF.