CSE 520: Real-Time Systems:Real-Time Scheduling (Single Core)

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  1. Benefit of Scheduling Analysis
    reduces development time by 50%
  2. Consequences of a a deadline miss for a hard deadline
    System fails if missed.
  3. Consequences of a a deadline miss for a soft deadline
    User may notice but system does not fail.
  4. Goal of a hard deadline
    guarantee no deadline miss.
  5. Goal of a soft deadline
    meet most deadlines, most of the time
  6. General purpose system scheduling
    • Fairness to all tasks; ergo no starvation
    • Optimize throughput
    • Optimize average performance
  7. Embedded systems scheduling
    • Meet ALL deadlines.
    • Fairness or throughput in NOT important
    • Hard Real-Time: worry about worst case performance.
  8. Task
    • Map to a process or thread
    • May be released several times
  9. Job
    An instance of a task.
  10. Periodic task
    • Ideal: inter-arrival time = period
    • General: inter-arrival time >= period.
  11. Aperiodic task
    Inter-arrival time does not have a lower bound.
  12. Ti (math)
  13. Pi (math)
    period OF a task Ti.
  14. Ci (math)
    Worst-case execution time OF a task Ti.
  15. Jik (math)
    Job k  OF  task Ti.
  16. Release time (math)
    Time when a job is ready.
  17. Response time Ri (math)
    is equal to the finish time  - release time
  18. Absolute deadline (math).
    Is equal to release time + Di (relative deadline)
  19. A job Jik misses its deadline if
    • Response time Ri > Di (relative deadline)
    • Finish time > absolute deadline.
  20. A task set is schedulable
    if ALL jobs meet their deadlines.
  21. Optimal scheduling algorithm
    A task set is unschedulable under the optimal algorithm, and therefore unschedulable under any other algorithms.
  22. Overhead (math)
    Time required for scheduling.
Card Set:
CSE 520: Real-Time Systems:Real-Time Scheduling (Single Core)
2016-10-23 03:36:11
Real Time Scheduling Computer Science Computers Systems

Cards cover Dr. Lu's lecture on Real-Time Scheduling from CSE 520s Real-Time Systems course Fall Semester of 2016
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