Performance Re-engineering of Consumer Electronic Applinances

Consumer electronic appliances are typical of embedded real-time systems which comprise electro-mechanical components and microprocessors possessing timing requirements. This paper formulates a re-engineering problem of such embedded systems and presents a solution approach. The re-engineering of an embedded system is defined as a development task of meeting newly imposed performance requirements after its hardware and software have been fully implemented. The performance requirements may include a real-time throughput and an input-to-output latency. The proposed solution approach is based on a bottleneck analysis and nonlinear optimization. Inputs to the approach include a system design specified with a process network and a set of task graphs, task allocation and scheduling, and a new real-time throughput requirement specified as a system’s period constraint. The solution approach works in two steps. In the first step, it determines bottleneck processes in the process network via estimation of process latencies. In the second step, it derives a system of constraints with performance scaling factors of processing elements being variables. It then solves the constraints for the performance scaling factors with an objective of minimizing the total hardware cost of the resultant system. These scaling factors suggest the minimal cost hardware upgrade to meet the new performance requirements. Since this approach does not modify carefully designed software structures, it helps reduce the reengineering cycle. The work reported in this paper was supported in part by KOSEF under grants 97-0102-05-01-3 and 981-0924-127-2, and by Automation and Systems Research Institute (ASRI) under grants 98-113 and 98-120. An earlier version of this paper appeared in preliminary form in the Proceedings of ACM Workshop on Languagues, Compilers, Tools for Embedded Systems, (May 1999).