Scheduling I/O Requests and Periodic Tasks with Random Execution Time

Abstract

This paper is particularly concerned with the problem of timing fault-tolerance in hard real-time systems. More precisely, the computing system considered here is composed of periodic tasks subject to timing faults (i.e deadline missing) that run on a single processor machine. A periodic task serially executes a set of software modules the execution times of which arestochastic. We propose the Deadline Mechanism as a means to provide fault-tolerance by ensuring timely completion of all the tasks through dynamic redundancy. Finally, we describe a procedure that enables us to jointly schedule nonpreempdve sporadic tasks and periodic tasks.