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Summary: Soft Real-Time on Multiprocessors: Are Analysis-Based Schedulers ReallyWorth It?

Summary: Soft Real-Time on Multiprocessors: Are Analysis-Based Schedulers ReallyWorth It?. Christopher J. Kennay , Jonathan L. Hermany , Bj¨orn B. Brandenburgy , Alex F. Millsz , and James H. Andersony Departments of Computer Sciencey and Statistics and Operations Researchz

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Summary: Soft Real-Time on Multiprocessors: Are Analysis-Based Schedulers ReallyWorth It?

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  1. Summary: Soft Real-Time on Multiprocessors: Are Analysis-Based SchedulersReallyWorth It? Christopher J. Kennay, Jonathan L. Hermany, Bj¨orn B. Brandenburgy, Alex F. Millsz, and James H. Andersony Departments of Computer Sciencey and Statistics and Operations Researchz The University of North Carolina at Chapel Hill Presented by GbadeboAyoade

  2. Introduction • EDF –earliest deadline first • EDF-HSB allows tasksetto be represented as mixture of soft real time and hard real time tasks • It allows for background scheduling and slack reclamation • Hard Realtime Task (HRT) • Soft Realtime Task(SRT) • Best Effort Jobs (BE)

  3. EDF –HSB algorithm Credit :Kenna et al

  4. Partitioning Formula

  5. Experiment • Comparism of EDF-HSB and linux CFS scheduler • Video application: Display and decoding task • Measurement of tardiness and display jitter

  6. Results Credit :Kenna et al

  7. Credit :Kenna et al

  8. Results Credit :Kenna et al

  9. Contribution • EDF-HSB guarantees Deadline tardiness bound • Stable BE throughput • Better performance due to background scheduling and slack reclamation

  10. Limitations • I/O suspension • Task dependencies • Memory management

  11. Summary: CPU Scheduling and Memory Management for Interactive Real-TimeApplicationsShinpei Kato °u Yutaka Ishikawa °uRagunathan

  12. Introduction • Constant bandwidth server • EDF-WM • EDF-WMR • Flexible CBS • Page swapping • Memory locking

  13. EDF WM Algorithm EDF-WM algorithm schedule tasks in a task set using the normal EDF algorithm and it assigns task i to a CPU that has enough free capacity to run the task, if such CPU is not found, EDF-WM splits the task i relative deadline and its execution cost based on the number of CPUs in the system and assigns each part to different CPUs New deadline = t+ originaldeadline/number of processors Credit Shipei et al

  14. Improvement • EDFWMR - CPU bandwidth reservation • FCBS CPU bandwidth reclamation Flexible CBS is proposed as an improvement to CBS by reclaiming unused reserved bandwidth and adding it to the reserved bandwidth of tasks that are running late

  15. Memory management • RTS memory reservation reduces page swap to disk • Full memory reservation- this lead to wastage of memory resources

  16. Improvement to memory reservation technique • Private-Shared-Anonymous Paging (PSAP). This is a dynamic memory reservation technique. • Memory reclamation • It reduces memory usage of RTS applications

  17. Experiment • Benchmarking of EDF WM against EDF WMR alogorithm using video application • Quality of service measured as stability of frame rate of the video playback.

  18. Results Performance by scheduling algorithms Credit Shipei et al

  19. Results Performance by memory reservation techniques. Credit Shipei et al

  20. Limitations • Grouping decode and display task as one component of a video application • I/O blocking • No consideration for Task dependency

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