Scheduling Aperiodic Tasks in Next Generation Embedded Real-Time Systems

In this paper we investigate a method of scheduling aperiodic tasks with a given periodic schedule, in a thermally constrained embedded real-time system. Considering thermal constraints is important for current and future processing systems because of the rapid rise in the power densities of processors, especially in multicore environments. Therefore, if thermal constraints are not considered, processor temperatures may increase to levels at which the reliability of the underlying semiconductor devices is compromised. As part of the proposed approach, an accurate and non-extensive temperature estimation scheme is presented. Based on the temperature estimation scheme, a scheduling scheme for aperiodic tasks in the presence of periodic tasks is proposed. The primary advantage of the proposed scheme is that it can account for temporal variations in task power consumption. The results show that our approach can provide significant improvements in aperiodic task response times, over schemes that do not allow tasks to have temporal variations in power consumption.