An effective fixed priority co-scheduling algorithm for periodic update and application transactions

Abstract

An important function of many Cyber-Physical Systems (CPS) is to provide a close monitoring of the operation environment to be able to adapt to changing situations effectively. One of the commonly applied techniques for that is to invoke time-constrained periodic application transactions to check the status of the operation environment. The status of the environment is represented by the values of the physical entities in the operation environment which are maintained as real-time data objects in a real-time database. Unfortunately, meeting the deadlines of application transactions and maintaining the quality of real-time data objects are conflicting with each other, because they compete for the same computation resources. To address this problem of update and application transactions co-scheduling problem, in this paper, we propose a fixed priority co-scheduling algorithm called Periodic Co-Scheduling ( PCS). PCS uses periodic update transactions to maintain the temporal validity of real-time data objects. It judiciously decides the priority orders among all the update and application transactions so that the constructed schedule can satisfy the deadline constraints of all the application transactions and at the same time maximize the qualities of the real-time data objects to ensure the correct execution of application transactions. The effectiveness of the algorithm is validated through extensive simulation experiments.

Guarantee the Quality-of-Service of Control Transactions in Real-Time Database Systems

“…Han et al [34] proposed a real-time co-scheduling algorithm, called Adaptive Earliest Deadline First Co-Scheduling (AEDF-Co) method, with the objective of determining a schedule for a given hybrid transaction set so that the deadline constraints of all the control transactions are satisfied while the quality of data (QoD) of the real-time data objects is maximized. Wang et al [35] proposed the Periodic Co-Scheduling (PCS) method that adopts a Fix Priority (FP) assignment scheme to maintain the temporal validity of real-time data objects. Han et al [12] proposed a co-scheduling algorithm called deferrable Coscheduling with Least Actual Laxity First (Co-LALF), in which the release times of update jobs are deferred for reducing the process workload.…”

Co-Scheduling of Hybrid Transactions on Multiprocessor Real-Time Database Systems

“…Han et al [24] proposed the AEDF-Co method which can be used in the systems with EDF scheduling. Wang et al [25] proposed the PCS method that adopts a Fix Priority (FP) assignment scheme. Han et al [8] proposed the Co-LALF method in which the release times of update jobs are deferred for reducing the process workload.…”