Multilevel Large-scale Module Placement/Floorplanning

• Main Authors: Hsun-Cheng Lee, 李訓政
• Other Authors: Yao-Wen Chang
• Format: Others
• Language: en_US
• Published: 2001
• Online Access: http://ndltd.ncl.edu.tw/handle/03188328582449737118

碩士 === 國立交通大學 === 資訊科學系 === 89 === We present in this thesis a multilevel floorplanning/placement framework based on the B*-tree representation, called MB*-tree, to handle the floorplanning and packing for large-scale building modules. The MB*-tree adopts a two-stage technique, clustering followed by declustering. The clustering stage applies quadratic programming (Lagrangian relaxation) to iteratively groups a set of hard (soft) modules based on a cost metric guided by area utilization and module connectivity, and at the same time establishes the geometric relations for the newly clustered modules by constructing a corresponding B*-tree for them. The declustering stage iteratively ungroups a set of the previously clustered modules (i.e., perform tree expansion) and then refines the placement/floorplanning solution by using a simulated annealing scheme. In particular, the MB*-tree preserves the geometric relations among modules during declustering, which makes the MB*-tree an ideal data structure for the multilevel floorplanning/placement framework. Experimental results show that the MB*-tree scales very well as the circuit size increases while the famous previous works, sequence pair, O-tree, and B*-tree, do not. For circuit sizes ranging from 49 to 9,800 modules and from 408 to 81,600 nets, the MB*-tree consistently obtains high-quality floorplans with dead spaces of less than 3.72% in empirically linear runtime, while standalone sequence pair, O-tree, and B*-tree can handle only up to 196, 196, and 1,960 modules in the same amount of runtime and result in the dead spaces of as large as 27.33%.