On the Implementation of Global Real-Time Schedulers

An empirical study of implementation tradeoffs (choice of ready queue implementation, quantum-driven vs. event-driven scheduling, and interrupt handling strategy) affecting global real-time schedulers, and in particular global EDF, is presented. This study, conducted using UNC's Linux-based LITMUSRT on Sun's Niagara platform, suggests that implementation tradeoffs can impact schedulability as profoundly as scheduling-theoretic tradeoffs. For most of the considered workloads, implementation scalability proved to not be a key limitation of global EDF on the considered platform. Further, a combination of a parallel heap, event-driven scheduling, and dedicated interrupt handling performed best for most workloads.