process--ANT

process--ANT - Operating Systems Structure and Design...

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Operating Systems Structure and Design Processes and threads process concept process scheduling: state, PCB, process queues, schedulers process operations: create, terminate, wait, … cooperating processes: shared memory, message passing threads
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Introduction An operating system executes a variety of programs batch systems - jobs time-shared systems - user programs or tasks job and program used interchangeably Process - a program in execution process execution proceeds in a sequential fashion A process contains program counter, stack and data section
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Process an operating system executes a variety of programs: batch system – jobs time-shared systems – user programs or tasks often, the terms job and process are used interchangeably a process is a program in execution a process (active entity) is both more and less than a program (passive entity) in addition to code, process involves program counter, registers, stack, data, … same program can produce more than one process (e.g., users running pine) the OS interleaves the execution of several processes to maximize processor utilization the OS supports InterProcess Communication (IPC) and user
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Major requirements OS must interleave the execution of a number of processes to maximize processor use while providing reasonable response time. OS must allocate resources to processes in conformance with a specific policy. Example: (i) higher priority, (ii) avoid deadlock. Support user creation of processes and IPC both of which may aid in the structuring of applications.
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Process creation Four common events that lead to a process creation are: 1) When a new batch-job is presented for execution. 2) When an interactive user logs in. 3) When OS needs to perform an operation (usually IO) on behalf of a user process, concurrently with that process. 4) To exploit parallelism an user process can spawn a number of processes. ==> concept of parent and child processes.
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Termination of a process Normal completion, time limit exceeded, memory unavailable Bounds violation, protection error, arithmetic error, invalid instruction IO failure, Operator intervention, parent termination, parent request A number of other conditions are possible. Segmentation fault : usually happens when you try write/read into/from a non-existent array/structure/object component. Or access a pointer to a dynamic data before creating it. (new etc.) Bus error: Related to function call and return. You have messed up the stack where the return address or parameters are stored.
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Tracing process execution consider 3 processes in memory: OS must manage process scheduling Dispatcher swaps out active process if (1) timeout occurs, or
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Simple queueing diagram in this simple system, a single queue suffices to store processes a process is either active (executing) or inactive (waiting) the dispatcher is code that assigns the CPU to one process or another it avoids wasted CPU cycles as the active process waits for I/
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This note was uploaded on 07/15/2011 for the course ECO 2023 taught by Professor Mr.raza during the Summer '10 term at FAU.

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process--ANT - Operating Systems Structure and Design...

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