Synchronization Protocols in Distributed Real-Time Systems

In many distributed real-time systems, the workload can be modeled as a set of periodic tasks, each of which consists of a chain of subtasks executing on different processors. Synchronization protocols are used to govern the release of subtasks so that the precedence constraints among subtasks are satisfied and the schedulabilityof the resultant system is analyzable. When different protocols are used , tasks can have different worst-case and average end-to-end response times. This paper focuses on distributed real-time systems that contain independent, periodic tasks scheduled by fixed-priority scheduling algorithms. It describes three synchronization protocols together with algorithms to analyze the schedulability of the system when these protocols are used. Simulation was conducted to compare the performance of these protocols with respect to the worst-case and average case end-to-end response times. The simulation experiment and the performance of the protocols are described.