An analysis of the AUTOSAR OS timing protection mechanism
ETFA'09 Proceedings of the 14th IEEE international conference on Emerging technologies & factory automation
A new implementation method of timer for periodic tasks
Journal of Embedded Computing - Advanced Topics on Embedded Computing
Sufficient real-time analysis for an engine control unit
Proceedings of the 21st International conference on Real-Time Networks and Systems
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In this paper we show how to take into account kernel overheads in classical real-time feasibility conditions for Fixed Priority (FP) scheduling where tasks having the same fixed priority are scheduled FP/FIFO. We consider the periodic task model with arbitrary deadlines and an event driven OSEK kernel. The feasibility conditions are based on the worst case response time computation of the tasks. We identify the sources of kernel overheads that influence the response time of the tasks. In such a system the overheads are due to the context switching that activates/terminates and reschedules tasks and to the granularity of the periodic timer used to implement the periodic task model. We show how to take into account those overheads in the classical FP/FIFO feasibility conditions. We compare the worst case response time obtained with kernel overhead to the response time obtained on a real event driven OSEK implementation. We show that the kernel overheads cannot be neglected and that the theoretical results are valid and can be used for a real-time dimensioning.