On the behavior of congestion minimization during placement

Typical placement objectives involve reducing net-cut cost or minimizing wirelength. Congestion minimization is least understood, however, it models routability accurately. In this paper, we study the congestion minimization problem during placement. We introduce the notion of consistent routing model and promote its adoption by placement systems. First, we show that in this model the wirelength objective is indeed a good measure of congestion by establishing that a placement with minimum wirelength has minimumtotal congestion. We show that minimizing wirelength may and in general, will create locally congested regions. We demonstrate that most other congestion related objectives are ill behaved and they should only be used in a post processing step. We then propose several novel congestion minimization objectives. One in particular, called over ow minimization with look-ahead, performs very well and can be computed very e ciently in an incremental manner. At the end, we propose a p...

• Type: Conference
• Year: 1999
• Where: ISPD
• Authors: Maogang Wang, Majid Sarrafzadeh
• Keywords: Congestion Minimization, Congestion Minimization Objectives, Congestion Minimization Problem, Hardware, ISPD 1999