Minimizing aperiodic response times in a firm real-time environment

Giorgio C. Buttazzo, Marco Caccamo

Research output: Contribution to journalArticlepeer-review

22 Scopus citations


In certain real-time applications, ranging from multimedia to telecommunication systems, timing constraints can be more flexible than scheduling theory usually permits. In this paper, we deal with the problem of scheduling hybrid sets of tasks, consisting of firm periodic tasks (i.e., tasks with deadlines which can occasionally skip one instance) and soft aperiodic requests, which have to be served as soon as possible to achieve good responsiveness. We propose and analyze an algorithm, based on a variant of Earliest Deadline First scheduling, which exploits skips to minimize the response time of aperiodic requests. One of the most interesting features of our algorithm is that it can easily be tuned to balance performance vs. complexity, for adapting it to different application requirements. Extensive simulation experiments show the effectiveness of the proposed approach with respect to existing methods. Schedulability bounds are also derived to perform off-line analysis.

Original languageEnglish
Pages (from-to)22-32
Number of pages11
JournalIEEE Transactions on Software Engineering
Issue number1
StatePublished - 1999
Externally publishedYes


  • Aperiodic service
  • Firm deadlines
  • Quality of service
  • Real-time scheduling
  • Skip


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