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Object-Oriented Design and Implementation of the OE-Scheduler in Real-time Environments

Object-Oriented Design and Implementation of the OE-Scheduler in Real-time Environments. Ilhyun Lee Cherry K. Owen Haesun K. Lee The University of Texas of the Permian Basin. Outline. Introduction Motivation and Objective UML Diagram for OE-Scheduler Implementation for OE-Scheduler

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Object-Oriented Design and Implementation of the OE-Scheduler in Real-time Environments

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  1. Object-Oriented Design and Implementation of the OE-Scheduler in Real-time Environments Ilhyun Lee Cherry K. Owen Haesun K. Lee The University of Texas of the Permian Basin

  2. Outline • Introduction • Motivation and Objective • UML Diagram for OE-Scheduler • Implementation for OE-Scheduler • Conclusion • Future Work

  3. Introduction • Real-Time System • Periodic Task Model • Object Oriented Design • OE-Scheduler

  4. Real-Time System • Computing system with a set of execution models that have timing constraints • Hard Real-Time System • Soft Real-Time System

  5. Hard Real-Time System

  6. Soft Real-Time System

  7. Periodic Task Model • A sequence of the same type of event occurring at constant intervals • Task : scheduling entity • Event : recurring instance of scheduling entity

  8. Object Oriented Design • Problems are modeled using objects • The object-oriented approach has the potential to reduce complexity, improve flexibility, and reduce expenses • Object reusability

  9. OE-Scheduler • Scheduler that generates a schedule of periodic tasks by the principle of eliminating unnecessary context switches under the rate monotonic algorithm • Guarantee the hard deadlines of an arbitrary number of periodic tasks in hard real-time environments • Object-oriented design

  10. Motivation • Future real-time system will run in highly dynamic behavior environments • Current our procedural scheduling algorithms cannot be efficiently applied to future real-time system • This observation motivated us to work on developing an object-oriented view-point of the OE-scheduler in hard real-periodic environments

  11. Objective • Developing an object-oriented view-point of the OE-scheduler that generates a schedule of periodic tasks by the principle of eliminating unnecessary context switches under the rate monotonic algorithmin hard real-periodic environments

  12. UML Diagram for OE-Scheduler • Class Diagram for OE-Scheduler • Sequence Diagram to Produce a OE-Schedule

  13. Class Diagram for OE-Scheduler

  14. Sequence Diagram to Produce a OE-Schedule

  15. Implementation for OE-Scheduler • Scheduling algorithm for OE-Scheduler • Test result of the object-oriented OE-Scheduler • Comparison table

  16. Scheduling Algorithm for OE-Scheduler • Step1.If Pij {i: 1..n, j: 0..n} arrives the system at the same time, pick the highest priority event of Pij {i: 1..n, j: 0..n}. Determine the Current Request Period (CRP) of the selected event.

  17. Scheduling Algorithm for OE-Scheduler • Step2. If the CRP of the selected event is odd, then go to Step3. Otherwise, if the CRP of the selected event is even, then calculate the Slack, the maximum amount of time that a scheduler can delay running the task without missing its current deadline, for the selected event. Delay the execution of the selected event until the Slack of the selected event becomes empty. When the Slack of the selected event becomes empty, schedule the selected event under the Rate Monotonic Algorithm. Go to Step4

  18. Scheduling Algorithm for OE-Scheduler • Step3.Immediately schedule the selected event under the Rate Monotonic Algorithm. • Step4. Go to Step1 until the final event is processed

  19. Scheduling Algorithm for OE-Scheduler

  20. Test Result of the Object-oriented OE-Scheduler • Record structure of the periodic task • Workload file: OE-schedule.txt • Menu-based user interface • The scheduling points with CRP • Schedule for 4 periodic task by OE-Scheduler

  21. Record Structure of the Periodic Task Workload

  22. Workload File: OE-schedule.txt

  23. Menu-based User Interface

  24. The Scheduling Points with CRP

  25. Schedule for 4 Periodic Task by OE-Scheduler

  26. Schedule for 4 periodic task by OE-Scheduler

  27. Comparison Table

  28. Conclusion • A study of dynamic behavior property in hard real-time environments • Robust design facilitates easier extension of the system to include more dynamic environments • Provide the real-time system engineers with greater flexibility to design future real-time systems • Helping the designer of real-time operating systems

  29. Future Work • Extend our scheduling algorithms to distributed and multiprocessor environments

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