Routing strategy of a prioritized limited multi-server processor-sharing system

Abstract

In this work, routing strategies of an arriving request to a server in a prioritized limited multi-server processor-sharing (PS) system are studied in order to optimize a given performance criterion. In this system, an arriving request enters the dispatcher, which routes this request to each server according to a predetermined strategy. In the prioritized limited PS server, a high-priority request is allocated a service ratio that is m (called the priority ratio) times greater than that of a low-priority request. Moreover, the sum of the number of the requests receiving service is restricted to a fixed value. The arriving request which cannot receive service will be queued (waiting system) or rejected (loss system). In this server, at the arrival (or departure) of a request, the extension (or shortening) of the remaining sojourn time of each request that is receiving service can be calculated using the number of requests and priority ratio. Employing a simulation program to execute these events and calculations enables us to analyze the performance of this system, such as the loss probability, mean sojourn time, and mean waiting time. Based on the evaluation results, the most suitable routing strategy for the loss or waiting system is clarified.