1. Slide 6-1 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 6

2. Slide 6-2 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 6 Implementing Processes, Threads, and Resources 6

3. Slide 6-3 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 6 OS Address Space OS Address Space Implementing the Process Abstraction Control Unit OS interface … Machine Executable Memory ALU CPU P i Address Space P i Address Space P i CPU P i Executable Memory P i Executable Memory P k Address Space P k Address Space … P k CPU P k Executable Memory P k Executable Memory P j Address Space P j Address Space P j CPU P j Executable Memory P j Executable Memory

4. Slide 6-4 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 6 External View of the Process Manager Hardware Application Program Application Program Device MgrProcess MgrMemory Mgr File Mgr UNIX Device MgrProcess MgrMemory Mgr File Mgr Windows CreateThread() CreateProcess() CloseHandle() WaitForSingleObject() fork() exec() wait()

5. Slide 6-5 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 6 Process Manager Responsibilities Define & implement the essential characteristics of a process and thread –Algorithms to define the behavior –Data structures to preserve the state of the execution Define what “things” threads in the process can reference – the address space (most of the “things” are memory locations) Manage the resources used by the processes/threads Tools to create/destroy/manipulate processes & threads Tools to time-multiplex the CPU – Scheduling the (Chapter 7) Tools to allow threads to synchronization the operation with one another (Chapters 8-9) Mechanisms to handle deadlock (Chapter 10) Mechanisms to handle protection (Chapter 14)

6. Slide 6-6 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 6 Modern Processes and Threads OS interface … … … P i CPU Thrd j in P i Thrd k in P i …

7. Slide 6-7 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 6 Processes &Threads Address Space Map Stack State Program Static data Resources Stack State Map

8. Slide 6-8 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 6 The Address Space Process Address Space Address Binding Executable Memory Other objects Files

9. Slide 6-9 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 6 Building the Address Space Some parts are built into the environment –Files –System services Some parts are imported at runtime –Mailboxes –Network connections Memory addresses are created at compile (and run) time

10. Slide 6-10 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 6 Tracing the Hardware Process Bootstap Loader Process Manager Interrupt Handler P1P1 P,2 PnPn … Machine is Powered up Initialization Load the kernel Service an interrupt Hardware process progress Execute a thread Schedule

11. Slide 6-11 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 6 The Abstract Machine Interface User Mode Instructions User Mode Instructions Application Program User Mode Instructions Abstract Machine Instructions Trap Instruction Supervisor Mode Instructions Supervisor Mode Instructions fork() create() open() OS

12. Slide 6-12 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 6 Context Switching Process Manager Interrupt Handler P1P1 P2P2 PnPn Executable Memory Initialization 1 2 3 4 5 7 Interrupt 8 9 6

13. Slide 6-13 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 6 Process Descriptors OS creates/manages process abstraction Descriptor is data structure for each process –Register values –Logical state –Type & location of resources it holds –List of resources it needs –Security keys –etc. (see Table 6.1 and the source code of your favorite OS)

14. Slide 6-14 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 6 Creating a Process in UNIX pid = fork(); UNIX kernel … Process Table Process Descriptor

15. Slide 6-15 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 6 Simple State Diagram Ready Blocked Running Start Schedule Request Done Request Allocate

16. Slide 6-16 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 6 UNIX State Transition Diagram Runnable Uninterruptible Sleep Running Start Schedule Request Done I/O Request Allocate zombie Wait by parent Sleeping Traced or Stopped Request I/O Complete Resume

17. Slide 6-17 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 6 Windows NT Thread States Initialized CreateThread Ready Activate Select Standby Running Terminated Waiting Transition Reinitialize Exit Preempt Dispatch Wait Wait Complete Dispatch

18. Slide 6-18 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 6 Resources R = {R j | 0  j < m} = resource types C = {c j  0 |  R j  R (0  j < m)} = units of R j available Reusable resource: After a unit of the resource has been allocated, it must ultimately be released back to the system. E.g., CPU, primary memory, disk space, … The maximum value for c j is the number of units of that resource Consumable resource: There is no need to release a resource after it has been acquired. E.g., a message, input data, … Notice that c j is unbounded. Resource: Anything that a process can request, then be blocked because that thing is not available.

19. Slide 6-19 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 6 Using the Model There is a resource manager, Mgr(R j ) for every R j Mgr(R j ) Process p i can only request n i  c j units of reusable R j p i can request unbounded # of units of consumable R j Process p i can request units of R j if it is currently running request Mgr(R j ) can allocate units of R j to p i allocate

20. Slide 6-20 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 6 A Generic Resource Manager Process Resource Manager Process Blocked Processes Resource Pool request() release() Policy

21. Slide 6-21 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 6 Process Hierarchies Parent-child relationship may be significant: parent controls children’s execution Ready-Active Blocked-Active Running Start Schedule Request Done Request Allocate Ready-Suspended Blocked-Suspended Suspend Yield Allocate Suspend Activate

22. Slide 6-22 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 6 Process Manager Overview Program Process Abstract Computing Environment File Manager Memory Manager Device Manager Protection Deadlock Synchronization Process Description Process Description CPU Other H/W Scheduler Resource Manager Resource Manager Resource Manager Resource Manager Resource Manager Resource Manager Memory Devices

23. Slide 6-23 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 6 UNIX Organization System Call Interface File Manager Memory Manager Device Manager Protection Deadlock Synchronization Process Description Process Description CPU Other H/W Scheduler Resource Manager Resource Manager Resource Manager Resource Manager Resource Manager Resource Manager Memory Devices Libraries Process Monolithic Kernel

24. Slide 6-24 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 6 Windows NT Organization Processor(s)Main MemoryDevices Libraries Process Subsystem User Subsystem Hardware Abstraction Layer NT Kernel NT Executive I/O Subsystem T T T T T T TT T