Fixed priority scheduling of periodic task sets with arbitrary deadlines

Abstract

This paper considers the problem of fixed priority scheduling of periodic tasks with arbitrary deadlines. A general criterion for the schedulability of such a task set is given. Worst case bounds are given which generalize the Liu and Layland bound. The results are shown to provide a basis for developing predictable distributed real-time systems.

Practical Schedulability Analysis for Generalized Sporadic Tasks in Distributed Real-Time Systems

“…A level-i busy period [7] is defined as a time interval [t 0 , t 0 + t) within which only jobs of priority i or higher are processed, and whose endpoints are consecutive level-i idle points. Here, a level-i idle point is a time instant t idle at which every job that is released before t idle and that has priority higher than or equal to i has completed by time t idle .…”

Analysis and Optimisation of Hierarchically Scheduled Multiprocessor Embedded Systems

“…Moreover, considering the effects of more and more factors that influence the timing properties of the tasks decreases the pessimism of the analysis by determining tighter worst case response times and leading to a smaller number of false negatives (which can appear when a system which is practically schedulable cannot be proven so by the analysis). Over the time, extensions have been offered to response time analysis for fixed priority scheduling by taking into account task synchronisation [Sha90], arbitrary deadlines [Leh90], precedence constraints between tasks [Pal99] and tasks with varying execution priorities [Gon91], arbitrary release times [Aud93], [Tin94c], tasks which suspend themselves [Pal98], tasks running on multiprocessor systems [Tin94a], [Pal98], etc. In [Ric02] and [Ric03], the authors model the multiprocessor heterogeneous systems as components that communicate through event streams and propose a technique for integrating different local scheduling policies based on such event-model interfaces.…”

A Fibre Channel Dimensioning for a Multimedia System with Deterministic QoS

“…The notion of level-i busy period introduced by [10] for preemptive FP/HPF scheduling is extended. In a non preemptive context, a task τ i can be delayed by a task τ j with a lower priority having started its execution before τ i 's release.…”