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Slide 6-1 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 6 Slide 6-2 Implementing Processes, Threads, and Resources Copyright © 2004 Pearson Education, Inc. 6 Operating Systems: A Modern Perspective, Chapter 6 Implementing the Process Abstraction Pi CPU Pj CPU Pi Executable Memory Pj Executable Memory Pk CPU … Pk Executable Memory OS Address Space CPU ALU Control Unit Pi Address Space Pk Address Space … Pj Address Space Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 6 Machine Executable Memory OS interface Slide 6-3 External View of the Process Manager Application Program Device Mgr UNIX Memory Mgr File Mgr exec() Memory Mgr File Mgr Process Mgr Device Mgr wait() CreateThread() CloseHandle() CreateProcess() WaitForSingleObject() Process Mgr fork() Windows Hardware Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 6 Slide 6-4 Process Manager Responsibilities Slide 6-5 • 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) Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 6 Modern Processes and Threads Thrdj in Pi Thrdk in Pi … Pi CPU … … OS interface … Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 6 Slide 6-6 Slide 6-7 Processes &Threads Stack State Copyright © 2004 Pearson Education, Inc. Static data Map Operating Systems: A Modern Perspective, Chapter 6 Program Map Resources Address Space Stack State Slide 6-8 The Address Space Address Space Address Binding Executable Memory Process Files Other objects 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 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 6 Slide 6-9 Slide 6-10 Tracing the Hardware Process Hardware process progress Machine is Powered up Bootstap Process Interrupt Loader Manager Handler P1 Load the kernel Initialization Execute a thread Schedule Pn … Service an interrupt Copyright © 2004 Pearson Education, Inc. P,2 Operating Systems: A Modern Perspective, Chapter 6 The Abstract Machine Interface Slide 6-11 Application Program Abstract Machine Instructions Trap Instruction User Mode Instructions fork() open() OS User Mode Instructions Copyright © 2004 Pearson Education, Inc. Supervisor Mode Instructions Operating Systems: A Modern Perspective, Chapter 6 create() Slide 6-12 Context Switching Executable Memory Initialization Interrupt 1 Process Manager 7 8 Interrupt Handler 2 4 3 P1 9 5 P2 6 Pn Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 6 Process Descriptors Slide 6-13 • 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) Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 6 Windows NT Process Descriptor EPROCESS KPROCESS NT Kernel NT Executive Copyright © 2004 Pearson Education, Inc. … uint32 uint32 … Byte … void … KernelTime; UserTime; state; *UniqueProcessId; Operating Systems: A Modern Perspective, Chapter 6 Slide 6-14 Windows NT Process Descriptor (2) Kernel process object including: Pointer to the page directory Kernel & user time Process base priority Process state List of the Kernel thread descriptors that are using this process Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 6 Slide 6-15 Windows NT Process Descriptor (3) Slide 6-16 Parent identification Exit status Creation and termination times. Memory status Security information executable image Process priority class used by the thread scheduler. A list of handles used by this process A pointer to Win32-specific information Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 6 Windows NT Thread Descriptor EPROCESS KPROCESS ETHREAD KTHREAD NT Kernel NT Executive Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 6 Slide 6-17 Creating a Process in UNIX pid = fork(); UNIX kernel Process Table … Copyright © 2004 Pearson Education, Inc. Process Descriptor Operating Systems: A Modern Perspective, Chapter 6 Slide 6-18 Slide 6-19 Creating a Process in NT CreateProcess(…); Win32 Subsystem ntCreateProcess(…); … ntCreateThread(…); NT Executive Handle Table NT Kernel … Copyright © 2004 Pearson Education, Inc. Process Descriptor Operating Systems: A Modern Perspective, Chapter 6 Windows NT Handles Application Handle User Space Supervisor Space Executive Object Kernel Object NT Executive NT Kernel Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 6 Slide 6-20 Slide 6-21 Simple State Diagram Request Done Running Request Schedule Start Allocate Blocked Copyright © 2004 Pearson Education, Inc. Ready Operating Systems: A Modern Perspective, Chapter 6 UNIX State Transition Diagram Request Wait by parent Done Running zombie Sleeping Schedule Request I/O Request Start Allocate Runnable I/O Complete Uninterruptible Sleep Copyright © 2004 Pearson Education, Inc. Resume Traced or Stopped Operating Systems: A Modern Perspective, Chapter 6 Slide 6-22 Slide 6-23 Windows NT Thread States CreateThread Initialized Activate Dispatch Exit Wait Running Waiting Ready Wait Complete Wait Complete Transition Preempt Reinitialize Select Terminated Dispatch Standby Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 6 Resources Resource: Anything that a process can request, then be blocked because that thing is not available. R = {Rj | 0 j < m} = resource types C = {cj 0 | RjR (0 j < m)} = units of Rj 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 cj 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 cj is unbounded. Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 6 Slide 6-24 Using the Model Slide 6-25 • There is a resource manager, Mgr(Rj) for every Rj • Process pi can request units of Rj if it is currently running pi can only request ni cj units of reusable Rj pi can request unbounded # of units of consumable Rj •Mgr(Rj) can allocate units of Rj to pi request Mgr(Rj) Process allocate Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 6 A Generic Resource Manager Resource Manager Policy Blocked Processes ProcessProcess Process request() Process release() Resource Pool Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 6 Slide 6-26 Process Hierarchies Slide 6-27 • Parent-child relationship may be significant: parent controls children’s execution Done Request Running Yield Request Schedule Suspend Ready-Active Activate Allocate Suspend Blocked-Active Suspend Start Ready-Suspended Allocate Blocked-Suspended Activate Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 6 Slide 6-28 Process Manager Overview Program Process Abstract Computing Environment File Manager Process Deadlock Description Protection Synchronization Device Manager Devices Copyright © 2004 Pearson Education, Inc. Memory Manager Memory Scheduler CPU Operating Systems: A Modern Perspective, Chapter 6 Resource Resource Resource Manager Manager Manager Other H/W Slide 6-29 UNIX Organization Process Process Libraries Process File Manager System Call Interface Process Deadlock Description Protection Synchronization Device Manager Memory Manager Scheduler Monolithic Kernel Devices Copyright © 2004 Pearson Education, Inc. Memory CPU Operating Systems: A Modern Perspective, Chapter 6 Resource Resource Resource Manager Manager Manager Other H/W Slide 6-30 Windows NT Organization T Process T T T Process Process T T T T T Libraries Subsystem Subsystem Subsystem User NT Executive NT Kernel Hardware Abstraction Layer Processor(s) Copyright © 2004 Pearson Education, Inc. Main Memory Operating Systems: A Modern Perspective, Chapter 6 I/O Subsystem Devices