Algorithms for scheduling hard aperiodic tasks in fixed-priority systems using slack stealing

This paper discusses the problem of jointly scheduling hard deadline periodic tasks and hard deadline aperiodic tasks using fixed priority methods. The approach is based on the slack stealing algorithm developed by the authors, and it assumes that the periodic deadlines must all be met. The paper develops a hard aperiodic acceptance test algorithm for guaranteeing tasks at any priority level, and it corrects an error in the original guarantee algorithm presented in Ramos-Thuel and Lehoczky (1993). It is shown that there is no optimal priority assignment for hard aperiodic task, but guidelines are given for choosing a good priority assignment