ch3 - Chapter 3: Processes Chapter 3: Processes Adapted to...

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Unformatted text preview: Chapter 3: Processes Chapter 3: Processes Adapted to COP4610 by Robert van Engelen 3.2 Silberschatz, Galvin and Gagne 2005 Operating System Concepts - 7 th Edition, Jan 19, 2005 Concurrency and Processes Concurrency and Processes Benefits of concurrency Multiple applications can run as processes at the same time Better resource utilization and performance One process runs on the CPU Another process performance disk I/O Completion time is shorter when running concurrently instead of sequentially Potential drawbacks of concurrency Applications must be protected from each other Overhead of switching and process coordination 3.3 Silberschatz, Galvin and Gagne 2005 Operating System Concepts - 7 th Edition, Jan 19, 2005 Process Concept Process Concept Process (aka job ): a loaded program in execution A process includes: Process control block (PCB) heap stack data section (global data) text section (code) Configuration of heap, stack, data and text sections may vary between systems A process in memory 3.4 Silberschatz, Galvin and Gagne 2005 Operating System Concepts - 7 th Edition, Jan 19, 2005 Process State Process State As a process executes, it changes state new : The process is being created running : Instructions are being executed waiting : The process is waiting for some event to occur ready : The process is waiting to be assigned to a process terminated : The process has finished execution 3.5 Silberschatz, Galvin and Gagne 2005 Operating System Concepts - 7 th Edition, Jan 19, 2005 Process Control Block (PCB) Process Control Block (PCB) PCB contains information associated with each process Process state Program counter (PC) CPU registers CPU scheduling information Memory-management information Accounting information I/O status information 3.6 Silberschatz, Galvin and Gagne 2005 Operating System Concepts - 7 th Edition, Jan 19, 2005 CPU Switch From Process to Process CPU Switch From Process to Process 3.7 Silberschatz, Galvin and Gagne 2005 Operating System Concepts - 7 th Edition, Jan 19, 2005 Process Scheduling Queues Process Scheduling Queues The process scheduler selects an available process from the ready queue for execution Ready queue The set of all processes residing in main memory, ready and waiting to execute Device queues The set of processes waiting for an I/O device Processes migrate among the various queues For example, when a process issues an I/O read operation that requires it to wait until the I/O operation completes 3.8 Silberschatz, Galvin and Gagne 2005 Operating System Concepts - 7 th Edition, Jan 19, 2005 Ready Queue and Various I/O Device Queues Ready Queue and Various I/O Device Queues 3.9 Silberschatz, Galvin and Gagne 2005 Operating System Concepts - 7 th Edition, Jan 19, 2005 Representation of Process Scheduling Representation of Process Scheduling Queueing-diagram of process scheduling 3.103....
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This note was uploaded on 10/11/2011 for the course COP 4610 taught by Professor Robertengelen during the Spring '11 term at FSU.

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ch3 - Chapter 3: Processes Chapter 3: Processes Adapted to...

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