Multicore parallel min-cost flow algorithm for CAD applications

Yinghai Lu, Hai Zhou, Li Shang, Xuan Zeng

Abstract: Computational complexity has been the primary challenge of many VLSI CAD applications. The emerging multicore and many-core microprocessors have the potential to offer scalable performance improvement. How to explore the multicore resources to speed up CAD applications is thus a natural question but also a huge challenge for CAD researchers. Indeed, decades of work on general-purpose compilation approaches that automatically extracts parallelism from a sequential program has shown limited success. Past work has shown that programming model and algorithm design methods have a great influence on usable parallelism. In this paper, we propose a methodology to explore concurrency via nondeterministic transactional algorithm design, and to program them on multicore processors for CAD applications. We apply the proposed methodology to the min-cost flow problem which has been identified as the key problem in many design optimizations, from wire-length optimization in detailed placement to timing-constrained voltage assignment. A concurrent algorithm and its implementation on multicore processors for min-cost flow have been developed based on the methodology. Experiments on voltage island generation in floorplanning demonstrated its efficiency and scalable speedup over different number of cores.