1. Operating Systems for Reconfigurable Embedded Platforms: Online Scheduling of Real-Time Tasks -Ramkumar Shankar

2. Reference 2  C.Steiger, H.Walder and M.Platzner, “Operating Systems for Reconfigurable Embedded Platforms:Online Scheduling of Real-Time Tasks”,IEEE Transactions on computers vol 53, No.11, pp. 1393-1407 Nov. 2004  Web link: http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=1336 761 http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=1336 761

3. Outline 3  Models and Limitations  Practical OS  Target Architecture  OS Modules  Scheduling Real-Time Tasks  Techniques for 1D and 2D model  Results, Conclusion and Future Scope

4. Preliminaries 4  Hardware task  Digital circuit that has been preplaced and prerouted.  Functional characteristics transparent to the OS.  Structural characteristics visible to the OS.  Area and timing requirements

5. 1D and 2D area model 5

6. Limitations of the area model 6  Internal Fragmentation  External Fragmentation  Assumes Homogeneity of the RC Device.  OS takes up some of the special resources  Tasks not relocatable

7. Target Architecture 7

8. Partitioning of the RC device 8

9. Operating system modules 9

10. Operating System Modules on CPU 10  Task Scheduler  Resource Manager  Task Preparation Unit  Raw Task Repository  COMM Driver  C/R Driver

11. Operating System Modules on RC Device 11  Task Controller  Memory Management Unit(MMU)  Device Drivers  OS Bridge

12. Scheduling Real-Time Tasks 12  Factors affecting the scheduling:  arrival time, execution time, deadline  Width, height  Constraints for the scheduler  Scheduled tasks must not overlap in space and time  The tasks must meet the deadline

13. 1D Horizon Technique 13  Execution list (E)  Maintains tasks (Ti), Finish time(fi) and placement(xi)  Reservation List (R)  Stores all tasks scheduled but not executing  Horizon List(H)  Stores the position and time step at which the units become available.

14. 1D Horizon Technique example 14

15. 1D Stuffing Technique 15  Maintains Execution and Reservation lists  Maintains a free space list.

16. Placement Algorithms and related issues 16  Free space management  Merging free spaces in Horizon Technique.  Mimic future tasks for Stuffing Technique.  Strip Packing  Scheduling tasks for 2D mesh – very costly

17. Evaluation 17

18. Results 18

19. Conclusion and Further Work 19  Design issues for RC Hardware operating system.  Scheduling techniques for 1D and 2D area models  Scheduling tasks for non-real time systems  Tasks with unknown execution times  Tasks without deadlines  Periodic tasks

20. 20

21. Questions 21