Method for Bottleneck Improvement on Queueing Network with Shared Store by Qualitative Reasoning

Abstract

This paper proposes a bottleneck improvement method on a new type of Queueing Network with Shared Stores (QNSS) using qualitative reasoning. Based on heuristics and knowledges obtained from evaluation experts, the authors have developed a new "qualitative reasoning" -based expert system, named BDES-SS (Bottleneck Diagnosis Expert System for QNSS), which can identify the bottlenecks, analyze the sources, and provide qualitative improvement plan option for QNSS. QNSS has the different types of bottlenecks in comparison with the ordinary QN. Primary types of bottlenecks in QNSS are "bottleneck Servers" with high utilization rates, "shared stores in overflow bottleneks", and "shared stores in underflow bottlenecks". In case of bottleneck improvement of QNSS with more than one bottlenecks, improvement Plans cause inconsistency one another. In order to improve all bottlenecks, BDES-SS first enumerates improvement plans for each of bottlenecks. Then, it selects a feasible Combination of the plans without inconsistency between bottlenecks. For this combination, the authors propose an approach by qualitative influence Propagation on the skeleton network which is a reduced from of given QNSS.