An EDF-based Scheduling Algorithm for Multiprocessor Soft Real-Time Systems

We consider the use of the earliest-deadline-first (EDF) scheduling algorithm in soft real-time multiprocessor systems. In hard real-time systems, a significant disparity exists between EDF-based schemes and Pfair scheduling (which is the only known way of optimally scheduling recurrent real-time tasks on multiprocessors): on M processors, all known EDF variants have utilization-based schedulability bounds of approximately M/2, while Pfair algorithms can fully utilize all processors. This is unfortunate because EDF-based algorithms entail lower scheduling and task-migration overheads. In work on hard real-time systems, it has been shown that this disparity in schedulability can be lessened by placing caps on per-task utilizations. In this paper, we show that it can also be lessened by easing the requirement that all deadlines be met. Our main contribution is a new EDF-based scheme that ensures bounded deadline tardiness. In this scheme, per-task utilizations must be capped, but over...

• Type: Conference
• Year: 2005
• Where: ECRTS
• Authors: James H. Anderson, Vasile Bud, UmaMaheswari C. Devi
• Keywords: ECRTS 2005, Hard Real-time Systems, Soft Real-time, Soft Real-time Multiprocessor