Area optimization of multi-functional processing units

Functions executed by a multifunctional processing unit (PU) correspond to clusters of operations in the specification, which are represented as signal flow graphs (SFGs). Because of high-throughput demands, the operations of each SFG are executed in parallel. Since operations for only one of the SFGs are executed at a given time, operations belonging to different SFGs can be executed on the same operator. Here, the most important part of the mapping of several SFGs onto one PU, which is the assignment of the SFGs operations to the PU´s operators, given a number of allocated operators, is considered. The problem is to find an operator assignment that minimizes the silicon area that is occupied by the PU´s interconnection consisting of multiplexers and wires. An approach based on local search algorithms such as iterative improvement and simulated annealing is presented. Although these algorithms are known to be generally applicable, it is shown that detailed knowledge of the operator assignment problem is required to obtain good results within acceptable CPU time limits for large problem instances.<>