Parallelizing post-placement timing optimization

Abstract

This paper presents an efficient modeling scheme and a partitioning heuristic for parallelizing VLSI post-placement timing optimization. Encoding the paths with timing violations into a task graph, our novel modeling scheme provides an efficient representation of the timing and spatial relations among timing optimization tasks. Our new partitioning algorithm then assigns the task graph into multiple sessions of parallel processes, so that interprocessor communication is completely eliminated during each session. This partitioning scheme is especially useful for parallelizing processes with heavily connected tasks and, therefore, high communication requirements. For circuits with 20-130 thousand cells, the partitioning heuristic achieves speedups in excess of 5× without degrading solution quality by dynamically utilizing 1-8 processors.