Dynamic priority assignment for aperiodic tasks in limited preemptive scheduling

Internet of Things (IoT) systems and other real-time systems are required to handle both periodic and aperiodic incoming tasks. In a situation in which periodic and aperiodic tasks are mixed into task scheduling using a fixed priority system, the schedulability of periodic tasks could be reduced due to interruptions by aperiodic tasks. This study analyzes the effects of aperiodic tasks on non-preemptive scheduling and limited preemptive scheduling methods, such as fixed preemption points, preemption threshold scheduling, and deferred preemptive scheduling, which have recently been proposed by complementarily combining fully preemptive and non-preemptive scheduling. This study then proposes an algorithm for assigning an appropriate priority to an aperiodic task by analyzing the worst-case response time of all tasks to enhance schedulability of both periodic and aperiodic tasks. Copyrights © 2020 The Institute of Electronics and Information Engineers