Schedulers for BGW tasks to guarantee quality of service of embedded real-time systems

Abstract

We present a new task model called BGW for preemptable, periodic task sets, scheduled on a uniprocessor embedded platform. The tasks may be subject to faults and the processor may be overloaded. According to BGW, any Black job has to execute a primary algorithm before deadline, any Grey job may execute either the primary or the back-up algorithm and any White job may be discarded. We describe several Earliest Deadline First (EDF) based scheduling frameworks suitable for this model. We also present and discuss the results of experiments that compare the EDF scheduler applied to conventional Liu and Layland task sets to various schedulers applied to BGW task sets. The Quality of Service is observed through metrics including ratio of deadline success, preemption rate, etc.