Author(s)

Sarah Tasneem, Lester Lipsky, Reda Ammar, Howard Sholl

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It is well known, in queueing theory, that the system performance is greatly influenced by scheduling policy. No universal optimum scheduling strategy exists in systems where individual customer service demands are not known a priori. However, if the distribution of job times is known, then the residual time (expected time remaining for a job), based on the service it has already received, can be calculated. Our particular research contribution is in exploring the use of this function to enhance system performance by increasing the probability that a job will meet its deadline. In a detailed discrete event simulation, we have tested many different distributions with a wide range of C2 and shapes, as well as for single and dual processor system. Results of four distributions are reported here. We compare with RR and FCFS, and find that in all distributions studied our algorithm performs best. In the study of the use of two slow servers versus one fast server, we have discovered that they provide comparable performance, and in a few cases the double server system does better.

Simulation, Residual Time Scheduling, Coefficient of Variation, M/G/C Queue, Processor Sharing

Tasneem, S. , Lipsky, L. , Ammar, R. and Sholl, H. (2010) A Residual Time Based Scheduling: Performance Modeling in M/G/C Queueing Applications. Journal of Software Engineering and Applications, 3, 746-755. doi: 10.4236/jsea.2010.38086.