quasi_static_rep03

Quasi-Static Scheduling for Real-Time Systems with Hard and Soft Tasks

Luis Alejandro Cortes Author homepage
 
Petru Eles Author homepage
Zebo Peng Author homepage

Technical Report, Embedded Systems Lab, Dept. of Computer and Information Science, Linköping University, September 2003.

ABSTRACT
This report addresses the problem of scheduling for real-time systems that include both hard and soft tasks. In order to capture the relative importance of soft tasks and how the quality of results is affected when missing a soft deadline, we use utility functions associated to soft tasks. Thus the aim is to find the execution order of tasks that makes the total utility maximum and guarantees hard deadlines. We consider intervals rather than fixed execution times for tasks. Since a purely off-line solution is too pessimistic and a purely on-line approach incurs an unacceptable overhead due to the high complexity of the problem, we propose a quasi-static approach where a number of schedules are prepared at design-time and the decision of which of them to follow is taken at run-time based on the actual execution times. We propose an exact algorithm as well as different heuristics for the problem addressed in this report.


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[AEP03] Luis Alejandro Cortes, Petru Eles, Zebo Peng, "Quasi-Static Scheduling for Real-Time Systems with Hard and Soft Tasks", Technical Report, Embedded Systems Lab, Dept. of Computer and Information Science, Linköping University, September 2003.
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