Incorporating Flexibility into Offline Scheduling

for Hard Real-Time Systems

A. Burns

Department of Computer Science,

University of York, UK

G. Fohler

Institut f?ur Technische Informatik,

Technische Universit?at Wien, Austria

Abstract

Static offline scheduling is ideally suited to deterministic applications because of the predictability of behaviour that is ensures, and the high resource utilisation that can be obtained. The run-time overhead is also minimised. Nondeterministic environments however require run-time flexibility in order to cope with modes changes, sporadic activities, transient overloads and resource failure. Offline schemes do not usually provide this flexibility. Following a discussion of a taxonomy of scheduling algorithm means of incorporating flexibility into offline methods are analysed. The proposals are investigated by considering their impact on the MARS architecture, an overview of which is included.

This work has been supported in part by ESPRIT Basic Research Action No. 3092 - Predictably Dependable Computer Systems and by Digital Equipment Corporation under contract EERP/AU-011.