Operational models for the evaluation of degradable computing systems

Abstract

Recent advances in multiprocessor technology have established the need for unified methods to evaluate computing systems performance and reliability. In response to this modeling need, this paper considers a general modeling framework which permits the modeling, analysis and evaluation of degradable computing systems. Within this framework, a simple and useful user-oriented performance variable is identified and shown to be a proper generalization of the traditional notions of system performance and reliability. The modeling and evaluation methods considered in this paper provide a relatively straightforward approach for integrating reliability and availability measures with performance measures. The hierarchical decomposition approach permits the modeling and evaluation of a computing system's subsystems (e.g., hardware, software, peripherals, interfaces, user demand systems) as a whole rather than the traditional methods of evaluating these subsystems independently. Accordingly, it becomes possible to evaluate the performance of the system software and the reliability of the system hardware simultaneously in order to measure the effectiveness of the system design. Since the performance variable introduced permits the characterization of the system performance according to the user's view of the systems, the results obtained represent more accurate assessments of the system's ability to perform than the existing performance or reliability measures.