Implementation of EDF, PIP and PCEP in BrickOS

1
Implementation of EDF, PIP and PCEP in BrickOS

• Sushil Pai
• spai_at_ncsu.edu

http//www4.ncsu.edu/spai/csc714
2
Objective

• BrickOS supports only Static Priority scheduling,
  which does not perform any kind of deadline
  monitoring and resource management.
• Hence, implement Earliest Deadline First,
  Priority Inheritance Protocol, Priority Ceiling
  Emulation Protocol

3
Current Implementation in BrickOS
4
The Process

• Implementing phase, period and deadline
• Use semaphores as Resource.
• Maintain a list of these resources
• Modify the task data structure to retain original
  priority
• Use Legos Network Protocol for debugging and
  viewing results

5
Sample Output

• TimeSlot Task Event
• ----------------------------
• 1256 Task0
• Info System Start time is 1256
• 14 Task1 Release
• 27 Task1 Start
• 39 Task1 Res2 held
• 53 Task1 Stage1
• 32 Task2 Release
• 79 Task2 Start
• 84 Task3 Release
• 98 Task2 Stage1
• 250 Info 5 is the New Priority
• 263 Task1 Res2 released
• 277 Info 1 is the Old Priority
• 263 Task2 Res2 held
• 311 Task2 Stage2
• 324 Task2 Res2 released
• 345 Task2 Over

Task2 Priority5
Task3 Priority3
Task1Priority1
Priority5
6
Conclusion

• Implemented EDF, PIP and PCEP
• Working of the schedulers was verified using LNP
• Yet to be done
• Implement PCEP with EDF
• Implement PIP with EDF