Budget allocations for hierarchical fixed-priority scheduling of sporadic tasks with deferred preemptions upon EDP resources

Abstract

In this paper we revisit the admission of applications upon a processor share modeled by the explicit-deadline periodic (EDP) resource-supply model. In particular, we consider applications that represent a fixed-priority sporadic task system. Existing works heavily build on the analysis of a hierarchy of preemptive task schedulers. We instead consider the feasibility of such tasks and applications for a hierarchy of deferred-preemptive schedulers, so that we can efficiently deal with the scenario where tasks and applications execute their work in non-preemptive chunks. Our model therefore gives better control over preemptions of tasks of different applications. We present exact analysis for deferred-preemptive scheduling of tasks on EDP resources. In addition, we propose algorithms for dimensioning an application's budget tightly.