EngineeringAlgorithms for Scheduling Taskswith Input Error and End - to - End DeadlinesW

This paper describes heuristic algorithms for scheduling preemptive, imprecise, composite tasks with input error and end-to-end timing constraints. Each composite task consists of a chain of component tasks, where each component task is made up of a mandatory part and an optional part. Whenever a component task uses imprecise input, the mandatory and optional parts of the component task may be extended in order to compensate for input error. We use a two-level scheduler. At the high level, the scheduler schedules the composite tasks preemptively on one processor, according to an existing algorithm for scheduling simple imprecise tasks. The result is the total amount of time budgeted to each composite task in order for all composite tasks to meet their end-to-end deadlines. The low-level scheduler then distributes the time budgeted for each composite task across its component tasks so as to minimize the output error of each composite task.