Deterministic and statistical deadline guarantees for a mixed set of periodic and aperiodic tasks

Minsoo Ryu, Seongsoo Hong

Research output: Contribution to journalArticle

2 Scopus citations


Current hard real-time technologies are unable to support a new class of applications that have real-time constraints but with dynamic request arrivals and unpredictable resource requirements. We propose two new admission control approaches to address this problem. First, we present an efficient schedulability test, called utilization demand analysis, to handle periodic and aperiodic tasks with deterministic execution times. The utilization demand is defined as the processor utilization required for a mixed task set to meet deadlines with certainty, thus for deterministic deadline guarantees. We show that the utilization demand analysis eliminates the need for complicated schedulability analysis and enables on-line admission control. Second, we present a statistical admission control scheme using effective execution times to handle stochastic execution times. Effective execution times are determined from the deadline miss probability demanded by the application and stochastic properties of task execution times. Every task is associated with an effective execution time and is restricted to using processor time not exceeding its effective execution time. This scheme allows every task to meet its deadline with a specified probability without being interfered with, and greatly simplifies the admission control when combined with the utilization demand analysis.

Original languageEnglish
Pages (from-to)72-87
Number of pages16
JournalLecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
StatePublished - 2004 Dec 1

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