Real-time scheduling of non-preemptive periodic tasks for continuous media retrieval

A real-time system should guarantee that each hard real-time task completes execution before its deadline. When non-preemptive earliest deadline first (EDF) scheduling is used for a set of periodic tasks, one can achieve full processor utilization, but its schedulability test is known to be an NP-hard problem. Continuous media (CM) retrieval is becoming an important application of real-time systems. In such an application, the CM server should provide CM data requested by clients within the specified deadline. We examine the O(1) time online schedulability tests for a set of equal computation time tasks and for a set of equal period tasks using non-preemptive EDF algorithm. We also demonstrate that these results can be used for scheduling a set of client requests in CM retrieval system.<
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