The Ceiling Protocol in Multi-moded Real-Time Systems1
Fixed-priority scheduling has become a very important approach for implementing real-time systems. Two key aspects of the method are its support for resource management using priority inheritance protocols and its ability to model modes of operation. In this paper, we discuss the impact of mode changes on the immediate inheritance priority ceiling protocol. We show that the approach adopted in Ada can result in an increased blocking time for tasks that can unnecessarily jeopardise their schedulability. We propose several solutions to help solve this problem.
KeywordsOperating Mode Mode Change Priority Assignment Sporadic Task Schedulability Analysis
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