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Summary: A Categorization of Realtime Multiprocessor
Scheduling Problems and Algorithms
John Carpenter, Shelby Funk, Philip Holman, Anand Srinivasan,
James Anderson, and Sanjoy Baruah
Department of Computer Science, University of North Carolina at Chapel Hill
1 Introduction
Realtime multiprocessor systems are now commonplace. Designs range from singlechip archi
tectures, with a modest number of processors, to largescale signalprocessing systems, such as
syntheticaperture radar systems. For uniprocessor systems, the problem of ensuring that deadline
constraints are met has been widely studied: e#ective scheduling algorithms that take into account
the many complexities that arise in real systems (e.g., synchronization costs, system overheads, etc.)
are well understood. In contrast, researchers are just beginning to understand the tradeo#s that
exist in multiprocessor systems. In this chapter, we analyze the tradeo#s involved in scheduling
independent, periodic realtime tasks on a multiprocessor.
Research on realtime scheduling has largely focused on the problem of scheduling of recurring
processes, or tasks. The periodic task model of Liu and Layland is the simplest model of a recurring
process [16, 17]. In this model, a task T is characterized by two parameters: a worstcase execution
requirement e and a period p. Such a task is invoked at each nonnegative integer multiple of p. (Task
invocations are also called job releases or job arrivals.) Each invocation requires at most e units
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