Exact Task Completion Time Aware Real-Time Scheduling Based on Supervisory Control Theory of Timed DES
Rajesh Devaraj, Arnab Sarkar, Santosh Biswas · 2018
Real-time scheduling strategies for safety-critical applications are primarily focused towards ensuring correctness, both functional and temporal. However, in order to guarantee deadlines for critical tasks, such strategies tend to assume very conservative Worst Case Execution Time (WCET) estimates for tasks, thus resulting in poor resource utilization. One way of improving this situation is through the evolution of scheduling mechanisms that can reclaim resources which are provisioned for critical functionalities at design time, but remain unused at run-time. Such reclaimed resources may prove to be very useful in executing lower criticality besteffort tasks. In this work, we present a Supervisory Control Theory of Timed Discrete Event Systems (SCT of TDES) based formal mechanism for synthesizing non-preemptive schedulers which can recognize exact completion times of tasks at runtime and allow the processor to be immediately relinquished instead of waiting up to WCETs of tasks. This approach allows reclamation of a higher amount of resources at run-time in comparison to models which consider worst-case execution time only. Conducted experiments have shown promising results and indicate to the practical efficacy of our approach.