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Chapitre 1.2

Chapitre 1.2. Systèmes d’exploitation. Layered Operating System model. Operating. Application. Hardware. System. Absolute Binary Loader. Central Memory. s3,t4. s3,t4. ABL. Command Interpreter. Central Memory. chess. s3,t4. Fmgr. Cmnd.Int. ABL. Interactive usage.

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Chapitre 1.2

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  1. Chapitre 1.2 Systèmes d’exploitation

  2. Layered Operating System model Operating Application Hardware System

  3. Absolute Binary Loader Central Memory s3,t4 s3,t4 ABL

  4. Command Interpreter Central Memory chess s3,t4 Fmgr. Cmnd.Int. ABL

  5. Interactive usage

  6. Batch Processing

  7. Organizes data on disk Hides the details of physical files Offers standardized file organizations Sequential Random Access Indexed Sequential Maintains File Directories File Manager

  8. Random Access Files • Space inefficient • Fast access

  9. Sequential Files • Space efficient • Slow access

  10. Indexed Sequential Files • Good compromise: • Space efficient • Access reasonably fast

  11. chess Cmnd.Int. Fmgr. ABL Command Interpreter

  12. Control by Command Interpreter Cmnd Interpreter Program X Start User Pgm Return to CMND.INT

  13. Interrupts Interrupt Handler

  14. DDA = 1 2 3 4 5 6 7 8 9 p1 #0 ND P2 COPY p2 #0 SC P3 COPY * 0 # p10 SC #10 SC P11 MUL p11 ADD SC KDA SC P12 p12 #0 KFL P13 COPY p13 ND #1 ND P14 ADD p3 ND #3 P3 P4 NE? p4 SC #321 P1 P5 NE? p5 #1 DDA P1 COPY Data Memory ND = SC = Arithmetic Unit KFL = KDA = Control Unit Interrupt Program Memory Interrupt handler p14 RTI

  15. Interrupt Handler Interrupt Handler Program X Start User Pgm Find cause int. Control Unit Return to int.handlr

  16. Interrupt Handler Based System Command interpreter User program Interrupt handler File manager A.B.L.

  17. Single-task Systems task completed active I/O completion activation start I/O Blocked (= busy waiting) load waiting for cpu

  18. Multi-task Systems task completed active preemption start I/O activation load waiting for cpu I/O completion (interrupt) blocked swap out

  19. Process Scheduling Which program becomes active when ? Job Scheduling (or Queue Management) Which programs reside in Central Memory ? Memory Management How much memory gets each program ? Output Spooling How to keep output of programs apart ? Multitasking Issues

  20. Non-preemptive Scheduling: Priorities are compared whenever the active program blocks itself a clock tick occurs (typically every 10 mS) Preemptive Scheduling Priorities are continuously compared. Process SchedulerAll programs have a priority and the one waiting with the highest priority becomes active.

  21. Process Priorities active -1 +1 p = p0 waiting for cpu blocked +1

  22. Manual selection (starting an application under Windows) Automatic selection based on priorities Based on the Round Robin algorithm Job SchedulerSelects the programs to be loaded in Central Memory

  23. Preempted tasks after t seconds Input queue Completed tasks Central memory New tasks Round Robin

  24. Allocates memory to each program Static Allocation Good Job Scheduling mandatory. Dynamic Allocation: Virtual Memory Job Scheduling not so important. Memory Management

  25. Virtual Memory Page Table 1 cm 004 2 pm 1003 3 pm 1004 4 pm 1007 5 cm 002 6 pm 1009 CM PM

  26. Program A Program B Program C Program D Output Spooling

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