An Upper Bound to the Lateness of Soft Real-Time Tasks Scheduled by EDF on Multiprocessors

Abstract

Abstract

A Hybrid Real-Time Scheduling Approach for Large-Scale Multicore Platforms

“…No variant of EDF is optimal, i.e., deadline misses can occur under each EDF variant in feasible systems (i.e., systems with total utilization at most the number of processors). It has been shown, however, that deadline tardiness under G-EDF is bounded in such systems, which is sufficient for many soft real-time applications [5,10]. (In contrast to G-EDF, for global static-priority algorithms, scenarios exist in which tardiness is unbounded even though total system utilization is at most M [4].…”

“…To assess differences in schedulability, we determined the schedulability of 100 randomly-generated task sets for different {cluster size, per-task utiliza- [10,100] (all units are in ms). Task execution costs were calculated from periods and utilizations.…”

“…Global scheduling algorithms are better able than partitioning approaches to utilize multiprocessor systems when system overheads are negligible. For example, on a system with M cores, the global earliest-deadline-first (EDF) algorithm can ensure bounded deadline tardiness (which is sufficient for many soft real-time applications) for any such task system if total utilization is at most M [5,10]. On the other hand, global algorithms are susceptible to large overheads on large platforms.…”

Parallel Real-Time Task Scheduling on Multicore Platforms

“…EDF is not optimal, so tasks may miss their deadlines. It has been shown, however, that deadline tardiness under EDF is bounded [5,16]. Additionally, jobs may be optionally and arbitrarily early released under EDF, as in Pfair scheduling, with no additional tardiness penalties.…”

Efficient Synchronization under Global EDF Scheduling on Multiprocessors

“…However, recent work has shown that if bounded deadline tardiness is acceptable, then such restrictions can be lifted for global EDF [5,18]. These results suggest that global EDF (henceforth referred to as just EDF) holds great promise as an effective scheduling method for real-time multiprocessor applications: if bounded tardiness is tolerable, then EDF enables applications to be deployed without the utilization restrictions and rigidity of partitioning schemes and without the potentially high implementation overheads of * Work supported by NSF grants CCR 0309825, CCR 0408996, and CCR 0541056.…”