Lecture3 - Silberschatz, Galvin and Gagne 2009 Operating...

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Unformatted text preview: Silberschatz, Galvin and Gagne 2009 Operating System Concepts 8 th Edition, Chapter 3: Processes 3.2 Silberschatz, Galvin and Gagne 2009 Operating System Concepts 8 th Edition Chapter 3: Processes Process Concept Process Scheduling Operations on Processes Interprocess Communication Examples of IPC Systems Communication in Client-Server Systems 3.3 Silberschatz, Galvin and Gagne 2009 Operating System Concepts 8 th Edition Objectives To introduce the notion of a process -- a program in execution, which forms the basis of all computation To describe the various features of processes, including scheduling, creation and termination, and communication To describe communication in client- server systems 3.4 Silberschatz, Galvin and Gagne 2009 Operating System Concepts 8 th Edition Process Concept Process a program in execution, it is much more than the program code (which is the text section of a process) To run a program, the OS creates a process A process includes: Identifier State Program counter Process stack (function parameters, return addresses and local variables) Data section (global variables) Heap (dynamically allocated memory) Program, etc 3.5 Silberschatz, Galvin and Gagne 2009 Operating System Concepts 8 th Edition Process in Memory A program is a file stored on disk (executable file) A program becomes a process when it is loaded in memory When created, a process is given memory not only for the program, but also for the stack, Two processes associated with a same program are different processes (for example, running two copies of firefox) 3.6 Silberschatz, Galvin and Gagne 2009 Operating System Concepts 8 th Edition Process Execution Consider three processes being executed All are in memory (plus the dispatcher, i.e. a process scheduler) Lets ignore virtual memory for this . 3.7 Silberschatz, Galvin and Gagne 2009 Operating System Concepts 8 th Edition Execution: processes point of view Each process runs to completion 3.8 Silberschatz, Galvin and Gagne 2009 Operating System Concepts 8 th Edition Execution: processor point of view Timeout I/O Timeout Timeout 3.9 Silberschatz, Galvin and Gagne 2009 Operating System Concepts 8 th Edition Process Creation Once the OS is required to create a new process it: Instantiates a data structure called process control block (PCB) to manage the process Assigns a unique process identifier Allocates space for the process Initializes process control block Creates or expand other data structures 3.10 Silberschatz, Galvin and Gagne 2009 Operating System Concepts 8 th Edition Process Control Block (PCB) Data structure in the OS containing information to manage a process Process state Program counter CPU registers CPU scheduling information Memory-management information Accounting information I/O status information 3.11 3....
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Lecture3 - Silberschatz, Galvin and Gagne 2009 Operating...

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