Optimal priority and threshold assignment for fixed-priority preemption threshold scheduling

L. Hatvani, S. Afshar, R.J. Bril

Research output: Chapter in Book/Report/Conference proceedingConference contributionAcademicpeer-review

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Fixed-priority preemption-threshold scheduling (FPTS) is a generalization of fixed-priority preemptive scheduling (FPPS) and fixed-priority non-preemptive scheduling (FPNS). Since FPPS and FPNS are incomparable in terms of potential schedulability, FPTS has the advantage that it can schedule any task set schedulable by FPPS or FPNS and some that are not schedulable by either. FPTS is based on the idea that each task is assigned a priority and a preemption threshold. While tasks are admitted into the system according to their priorities, they can only be preempted by tasks that have priority higher than the preemption threshold. This paper presents a new optimal priority and preemption threshold assignment (OPTA) algorithm for FPTS which in general outperforms the existing algorithms in terms of the size of the explored state-space and the total number of worst case response time calculations performed. The algorithm is based on back-tracking, i.e. it traverses the space of potential priorities and preemption thresholds, while pruning infeasible paths, and returns the first assignment deemed schedulable. We present the evaluation results where we compare the complexity of the new algorithm with the existing one. We show that the new algorithm significantly reduces the time needed to find a solution. Through a comparative evaluation, we show the improvements that can be achieved in terms of schedulability ratio by our OPTA compared to a deadline monotonic priority assignment.

Original languageEnglish
Title of host publicationEWiLi 2016 : Embedded Operating Systems workshop : Proceedings of the Embedded Operating Systems Workshop co-located with the Embedded Syetems Week (ESWEEK 2016), Pittsburgh, PA, USA, October 6, 2016
EditorsJ. Boukhobza, M.D. Santambrogio, F. Singhoff
Number of pages6
Publication statusPublished - Oct 2016
EventEWiLi 2016, Embedded Operating Systems Workshop, October 6, 2016, Pittsburgh, PA, USA - Pittsburgh, United States
Duration: 6 Oct 20166 Oct 2016

Publication series

NameCEUR Workshop Proceedings
ISSN (Electronic)1613-0073


WorkshopEWiLi 2016, Embedded Operating Systems Workshop, October 6, 2016, Pittsburgh, PA, USA
Abbreviated titleEWiLi 2016
Country/TerritoryUnited States


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