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Real-time scheduling algorithms for multiprocessor systems have been the subject of considerable recent interest. For such an algorithm to be truly useful in practice, support for semaphore-based locking must be provided. However, for many global scheduling algorithms, no such mechanisms have been proposed. Furthermore, in the partitioned case, most prior(More)
We present a real-time, Linux-based testbed called LITMUS RT , which we have developed for empirically evaluating multiprocessor real-time scheduling algorithms. We also present the results from such an evaluation, in which partitioned earliest-deadline-first (EDF) scheduling, pre-emptive and nonpreemptive global EDF scheduling, and two variants of the(More)
In the domain of multiprocessor real-time systems, there has been a wealth of recent work on scheduling, but relatively little work on the equally-important topic of synchronization. When synchronizing accesses to shared resources, four basic options exist: lock-free execution, wait-free execution, spin- based locking, and suspension-based locking. To our(More)
We present a real-time, Linux-based testbed called LITMUS RT , which we have developed for empirically evaluating multiprocessor real-time scheduling algorithms. We also present the results from such an evaluation, in which partitioned earliest-deadline-first (EDF) scheduling, pre-emptive and nonpreemptive global EDF scheduling, and two variants of the(More)
In this paper, we develop an adaptive scheduling framework for changing the processor shares of tasks—a process called reweighting—on real-time multiprocessor platforms. Our particular focus is adaptive frameworks that are deployed in environments in which tasks may frequently require significant share changes. Prior work on enabling real-time adaptivity on(More)
We consider the problem of task reweighting in fair-scheduled multiprocessor systems wherein each task's processor share is specified as a weight. Task reweighting can be used as a means for consuming (or making available) spare processing capacity. In this paper, we propose a multiprocessor reweighting scheme that can change a task's processor share with(More)
We consider schemes for enacting task share changes—a process called reweighting—on real-time multiprocessor platforms. Our particular focus is reweighting schemes that are deployed in environments in which tasks may frequently request significant share changes. Prior work has shown that fair scheduling algorithms are capable of reweighting tasks with(More)
In this paper, we develop an adaptive scheduling framework for changing the processor shares of tasks—a process called reweighting—on real-time multiprocessor platforms. Our particular focus is adaptive frameworks that are deployed in environments in which tasks may frequently require significant share changes. Prior work on enabling real-time adaptivity on(More)
This paper describes an approach for identifying On-tology components by using Self-Organizing Maps (SOM). Our system represents the knowledge contained in a particular domain, any kind of digital archive, by assembling and displaying its ontology components. This novel approach provides a solution to the problem of semi-automatic ontology construction ,(More)