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Stochastically minimizing total delay of jobs subject to random deadlines. (English) Zbl 1134.68326

Summary: This paper analyzes a scheduling system where a fixed number of nonpreemptive jobs is to be processed on multiple parallel processors with different processing speeds. Each processor has an exponential processing time distribution and the processors are ordered in ascending order of their mean processing times. Each job has its own deadline that is exponentially distributed with rate \(\beta\), independent of the deadlines of other jobs and also independent of job processing times. A job departs the system as soon as either its processing completes or its deadline occurs. We show that there exists a simple threshold strategy that stochastically minimizes the total delay of all jobs. The policy depends on distributions of processing times and deadlines, but is independent of the rate of deadlines. When the rate of the deadline distribution is 0 (no dead-lines), the total delay reduces to the flowtime (the sum of completion times of all jobs). If each job has its own probability of being correctly processed, then an extension of this policy stochastically maximizes the total number of correctly processed, nontardy jobs. We discuss possible generalizations and limitations of this result.

MSC:

68M20 Performance evaluation, queueing, and scheduling in the context of computer systems
60K30 Applications of queueing theory (congestion, allocation, storage, traffic, etc.)
90B36 Stochastic scheduling theory in operations research
Full Text: DOI

References:

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