Firm Aperiodic Task Scheduling in Hard Real-time Multiprocessor Systems

The problem of extending monoprocessor methods to multiprocessors for scheduling soft aperiodic tasks has been addressed and evaluated in previous works, where the most usual goal for aperiodic tasks is minimising response times. This paper introduces a new problem where the goal for aperiodic tasks is guaranteeing their deadlines. Guaranteeing aperiodic deadlines is done using an acceptance test based on extending the slack stealing algorithm for EDF schedulers in a way such that it can guarantee a given response time for an aperiodic task with the assumption that it can migrate from one processor to another. Proposed solutions are evaluated through extensive simulations in terms of acceptance ratios for different periodic workload conditions. Results show that allowing task migration among processors can improve the acceptance ratio by an almost a 50%. Other interesting parameters like the number of required processor switches are also evaluated. Copyright c © 2003 IFAC