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Scheduling of Distributed Embedded Real-Time Systems with Power Consumption and Reliability Constraints

Kusedghi, Amir | 2012

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 43893 (19)
  4. University: Sharif University of Technology
  5. Department: Computer Engineering
  6. Advisor(s): Ejlali, Alireza
  7. Abstract:
  8. Embedded systems usually need to have a Real-time function so that the time constraint has been one of the most essential attributes of these systems. In the design phase of these systems a scheduler must be presented by the designer so that the observance of system deadlines can be guaranteed( Hard Real-time Systems). Safety-critical applications not only must guarantee system deadlines despite the hard timing constraints in the presence of error, but also must operate correctly and tolerate the error. In some of these applications reducing power consumption is one of the most important objectives because of limited supply energy. The purpose of this project is to firstly study the methods of scheduling distributed real-time embedded systems from the point of Reliability and Energy consumption and then introduce a scheduling method of these systems which reliability and energy consumption are specifically considered.
    In the following research, a scheduling on a system with pseudo-cold Stand-by Sparing hardware redundancy is introduced which the hardware redundancy had been provided with distribution. Scheduling policy on the primary unit is EDF while spare unit uses pseudo-static EDL. Task model is considered periodic and elastic which the tasks execution can be preemptive. It is shown that despite of discrete voltage levels with elastic feature of tasks, actions can be done to reduce power consumption in the presence of fault-tolerance and satisfaction of real-time constraints. In this method dynamic and static slack times are used to reduce processor frequency of primary unit with DVS technique and with proper scheduling policies the execution overlap time of each task on both processors are reduced. The proposed system has the ability to accept new arrival tasks during the execution of primary task-set in some circumestances that in no research has been considered. Also the normalized energy consumption is reduced 14% in the best case
  9. Keywords:
  10. Real-Time Scheduling ; Reliability ; Safety-Critical Application ; Embedded Real-Time Distributed

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