Slack-based global multiprocessor scheduling of aperiodic tasks in parallel embedded real-time systems

We provide a constant time schedulability test and priority assignment algorithm for an on-line multiprocessor server handling aperiodic tasks. Dhall's effect is avoided by dividing tasks in two priority classes based on their utilization: heavy and light. The improvement in this paper is due to assigning priority of light tasks based on slack - not on deadlines. We prove that if the load on the multiprocessor stays below (3 - radic5)/2 ap 38.197%, the server can accept an incoming aperiodic task and guarantee that the deadlines of all accepted tasks will be met. This is better than the current state-of- the-art algorithm where the priorities of light tasks are based on deadlines (the corresponding bound is in that case 35.425%).