Exact Speedup Factors for Linear-Time Schedulability Tests for Fixed-Priority Preemptive and Non-preemptive Scheduling

Georg von der Bruggen, Jian-Jia Chen, Robert Ian Davis, Wen-Hung Kevin Huang

Research output: Contribution to journalArticlepeer-review


In this paper, we investigate the quality of several linear-time schedulability tests for preemptive and non-preemptive fixed-priority scheduling of uniprocessor systems. The metric used to assess the quality of these tests is the resource augmentation bound commonly known as the processor speedup factor. The speedup factor of a schedulability test corresponds to the smallest factor by which the processing speed of a uniprocessor needs to be increased such that any task set that is feasible under an optimal preemptive (non-preemptive) work-conserving scheduling algorithm is guaranteed to be schedulable with preemptive (non-preemptive) fixed priority scheduling if this
scheduling test is used, assuming an appropriate priority assignment. We show the surprising result that the exact speedup factors for Deadline Monotonic (DM) priority assignment combined with sufficient linear-time schedulability tests for implicit-, constrained-, and arbitrary-deadline task sets are the same as those obtained for optimal priority assignment policies combined with exact schedulability tests. Thus in terms of the speedup-factors required, there is no penalty in using DM priority assignment and simple linear schedulability tests.
Original languageEnglish
Pages (from-to)1-5
Number of pages5
JournalInformation Processing Letters
Early online date5 Aug 2016
Publication statusE-pub ahead of print - 5 Aug 2016

Bibliographical note

© 2016 Elsevier B.V. All rights reserved. This is an author-produced version of the published paper. Uploaded in accordance with the publisher’s self-archiving policy. Further copying may not be permitted; contact the publisher for details. Embargo period : 12 months


  • Speedup factors
  • schedulability tests
  • fixed-priority
  • real-time scheduling
  • preemptive scheduling
  • non-preemptive scheduling

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