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Probabilistic QoS Guarantees: Fixed and Dynamic Priority Scheduling


In?s El Korbi, Skander Azzaz, Leila Azouz Saidane


Vol. 6  No. 9  pp. 1-21


Generally, with a limited number of fixed priorities within a network, applications sharing a same priority are scheduled according to First in First out discipline. This policy is called FP/FIFO. However real time applications have deadline requirements which aren’t taken into account with the discipline. That is why we propose to introduce the Earliest Deadline First discipline to schedule applications sharing a same priority. In another hand, we are interested in providing quantitative Quality of Service guarantees to various types of real-time applications. Hard real-time applications have strong deadline requirements whereas soft real-time applications have only soft deadline requirements. A probabilistic approach is used to guarantee probabilistic adapted to applications requirements. The response time probability density function is then computed to obtain the probability that the response time doesn’t exceed a given deadline.


Quality of service, Probabilistic guarantee, fixed priority, dynamic priority, EDF, deadline, end-to-end response time, M/G/1 station, Head of Line discipline.