Deadline monotonic scheduling theory and application

N. C. Audsley*, A. Burns, A. J. Wellings

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Scheduling theories are now sufficiently mature that a genuine engineering approach to the construction of hard real-time systems is possible. In this paper we discuss the application of Deadline Monotonic Scheduling Theory (DMST). This theory is an extension of the more familiar approach based on rate monotonic priority assignment. The model presented can accomodate periodic and sporadic processes, different levels of criticality, process interaction and blocking, precedence constrained processes and multi-deadline processes. It is particularly well integrated with the use of Immediate Priority Ceiling Inheritance for control over process blocking. A basic pseudo-polynomial schedulability test is outlined and then supplemented by the introduction of offsets to control jitter, and period transformation to enable critical (hard) processes to be "protected" during potential transient overloads. These mathematical techniques derived within DMST can help designers experiment with alternative formulations and prove essential properties of systems before they are deployed.

Original languageEnglish
Pages (from-to)71-78
Number of pages8
JournalControl engineering practice
Issue number1
Publication statusPublished - 1 Jan 1993


  • hard real-time scheduling
  • rate monotonic
  • schedulability constraints

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