component of operating system.

The Operating system performs large number of functions . Each function is carried out by a component of the operating system. the component of an operating system  are :

1. Process management sub-system.
2.Memory management sub-system.
3.File management sub-system .
4.I/O system management sub-system.
5.Secondary storage management sub-system.
6.Network management sub-system.
7.Protection sub-system.
8.User interface sub-system.

Process Management


“An operating system is a collection of programs that manage system resources such as processor memory, input / output devices (I / O devices) and file systems. . "All these systems resources are valuable, which helps the operating system to work co-operatively with each other."

The operating system keeps track of the status of each resource and allocates resources for different processes based on a certain policy and also decides how long a process is resourcing. Will use Lastly, it also de-allocates the allocated resources.

As far as processor management is concerned, the management of physical processors (CPUs) by the operating system means allocating processors for processes or tasks or jobs (process or tasks or tasks or jobs). This is called processor management.

The process that executes the program is called process. That is, when any program is running, it is called a process, which performs a particular task. For example, Shell or Command Interpreter is also a process in the UNIX operating system, which accepts the command given by the user and executes it as a process. Be aware that whenever a process is created, it needs various system resources, such as CPU time, memory registers, files, etc.

As we know, in a Time-Shared System, multiple users' programs reside in memory simultaneously and share an equal portion of CPU time for every user's program, which is of a few seconds. Occurred (allocated). When the CPU executes a program or command, a process is created. When one process stops executing after its allocated time, the other process starts running. When a process is temporarily suspended, the information of that process is stored in the memory location, so that when the execution of that process starts again, it Start executing from where the process was suspend.


In many operating systems, the information of each process is stored in the process tables. The operating system also provides system calls (system calls) to manage the processes. In these system calls, create and kill system calls are the main ones.

Process Concept


What is the difference between program and process? 

Programs where there are passive entities, eg, storing program codes on disk as files. A process is an active entity with a program counter that specifies executing the next instruction and a set of resources related to the process. Only one processor can be shared between several processes by scheduling policy.

Processes Hierarchies


When a process is created, it creates other processes and then new processes can create other processes. The process that has created another process is called parent process and the new process is called the child process of that process. In this way, the process tree is created by one process creating other processes.

Process State


Any one of the following can be a state. A process can be in any one of the following states.

    New
    Ready
    Running
    Waiting
    Terminated


New State

In this state, any process becomes new.

Ready state

After any process is started or started or create, soon (immediately) comes to ready state. Any process in this state keeps waiting for the processor to allocate.

Running State

When the instructions of a process are executed, the process is called in the running state. When a process gets control from the CPU and other system resources, it starts executing. The running process can transfer control to execute another process, through the sequence of input / output (I / O) operations during the execution of the running process. Contents during input / output (I / O) operations by running process Transfer control to another process (which will be ready to run) or transfer to the operating system depends on the scheduling policy of the operating system.

Waiting State


In this state, a process keeps waiting for an event to occur. For example, waiting for input / output (I / O) operations to complete.

Terminated


When a process executes its last statement, it is terminated by the operating system. This state of the process is called Terminated State. In a terminated state, a process can also return data to its parent process. A process can also be terminated from another process created by a system call.


 Memory management

Memory management is the function of an operating system that handles and manages primary memory. In addition, it also serves to rotate the process between memory and disk during execution.

Memory management keeps track of all memory locations; Even if they are allocated to a process or they are sitting empty. It also examines how much memory is required for which process.

Deciding which processes will be given memory at any time - it is also the task of memory management.

Whenever a memory is free, that is, it is empty after executing a process, then memory management keeps updating its records accordingly.

File management 

A file management system is a type of software that manages data files in a computer system. It has limited capabilities and is designed to manage individual or group files, such as special office documents and records. It may display report details, like owner, creation date, state of completion and similar features useful in an office environment.

A file management system is also known as a file manager. 

I/O management  

The method used to transfer information between processor and peripheral devices. It is called input output interface.

Special communication links are required to interface the peripheral devices connected with the computer with the processor. In computer systems, there are specialized hardware components between the processor and peripherals. These hardware components are those that manage or control input-output transfer.

These components are called input-output interface units because they provide communication links between the processor and the peripheral.


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