Date: April 10, 2006
Creator: Li, Wenming; Kavi, Krishna & Akl, Robert G.
Description: This article discusses a non-preemptive scheduling algorithm for soft real-time systems. Real-time systems are often designed using preemptive scheduling and worst-case execution time estimates to guarantee the execution of high priority tasks. There is, however, an interest in exploring non-preemptive scheduling models for real-time systems, particularly for soft real-time multimedia applications. In this paper, the authors propose a new algorithm that uses multiple scheduling strategies for efficient non-preemptive scheduling of tasks. The goal is to improve the success ratio of the well-known Earliest Deadline First (EDF) approach when the load on the system is very high and to improve the overall performance in both underloaded and overloaded conditions. The authors' approach, known as group EDF (gEDF) is based on dynamic grouping of tasks with deadlines that are very close to each other, and using Shortest Job First (SJF) technique to schedule tasks within the group. The authors present results comparing gEDF with other real-time algorithms including EDF, Best-effort, and Guarantee, by using randomly generated tasks with varying execution times, release times, deadlines and tolerance to missing deadlines, under varying workloads. The authors believe that grouping tasks dynamically with similar deadlines and utilizing a secondary criteria, such as minimizing the total ...
Contributing Partner: UNT College of Engineering