Found 2065 Articles for Operating System

Context Switching involves storing the context or state of a process so that it can be reloaded when required and execution can be resumed from the same point as earlier. This is a feature of a multitasking operating system and allows a single CPU to be shared by multiple processes.A diagram that demonstrates context switching is as follows −In the above diagram, initially Process 1 is running. Process 1 is switched out and Process 2 is switched in because of an interrupt or a system call. Context switching involves saving the state of Process 1 into PCB1 and loading the ... Read More

Process Scheduling handles the selection of a process for the processor on the basis of a scheduling algorithm and also the removal of a process from the processor. It is an important part of multiprogramming operating system.There are many scheduling queues that are used in process scheduling. When the processes enter the system, they are put into the job queue. The processes that are ready to execute in the main memory are kept in the ready queue. The processes that are waiting for the I/O device are kept in the I/O device queue.The different schedulers that are used for process ... Read More

A process is an active program. It can also be said as a program that is under execution. It is more than the program code as it includes the program counter, process stack, registers, program code etc. Compared to this, the program code is only the text section.A process passes through different states as it executes. These states may be different in different operating systems. However, the common process states are explained below with the help of a diagram −NewThis is the state when the process has just been created. It is the initial state in the process life cycle.ReadyIn ... Read More

Interprocess communication is the mechanism provided by the operating system that allows processes to communicate with each other. This communication could involve a process letting another process know that some event has occurred or the transferring of data from one process to another.A diagram that illustrates interprocess communication is as follows −Synchronization in Interprocess CommunicationSynchronization is a necessary part of interprocess communication. It is either provided by the interprocess control mechanism or handled by the communicating processes. Some of the methods to provide synchronization are as follows −SemaphoreA semaphore is a variable that controls the access to a common resource ... Read More

A zombie process is a process whose execution is completed but it still has an entry in the process table. Zombie processes usually occur for child processes, as the parent process still needs to read its child’s exit status. Once this is done using the wait system call, the zombie process is eliminated from the process table. This is known as reaping the zombie process.A diagram that demonstrates the creation and termination of a zombie process is given as follows −Salient points of Zombie ProcessesSome of the salient points related to zombie processes are as follows −All the memory and ... Read More

Process Control Block is a data structure that contains information of the process related to it. The process control block is also known as a task control block, entry of the process table, etc.It is very important for process management as the data structuring for processes is done in terms of the PCB. It also defines the current state of the operating system.Structure of the Process Control BlockThe process control stores many data items that are needed for efficient process management. Some of these data items are explained with the help of the given diagram −The following are the data ... Read More

A process is an active program i.e a program that is under execution. It is more than the program code as it includes the program counter, process stack, registers, program code etc. Compared to this, the program code is only the text section.A program is not a process by itself as the program is a passive entity, such as file contents, while the process is an active entity containing program counter, resources etc.Process StatesA process changes its state as it executes. This state partially depends on the current activity of a process. The different states that a process is in ... Read More

The interface between a process and an operating system is provided by system calls. In general, system calls are available as assembly language instructions. They are also included in the manuals used by the assembly level programmers.System calls are usually made when a process in user mode requires access to a resource. Then it requests the kernel to provide the resource via a system call.Types of System CallsThere are mainly five types of system calls. These are explained in detail as follows −Here are the types of system calls −Process ControlThese system calls deal with processes such as process creation, ... Read More

The loadable kernel modules in an operating system is an object file that contains code to extend the running kernel, which is also known as the base kernel. The loadable kernel modules are used to add support for file systems, hardware, system calls etc.An image that shows the loadable modules of the operating system is as follows −The different types of kernels in the operating system that may require loadable kernel modules are −MicrokernelA microkernel is the minimum software that is required to correctly implement an operating system. This includes memory, process scheduling mechanisms and basic inter-process communication.The microkernel contains ... Read More

Debugging is the process of finding the problems in a computer system and solving them. There are many different ways in which operating systems perform debugging. Some of these are −Log FilesThe log files record all the events that occur in an operating system. This is done by writing all the messages into a log file. There are different types of log files. Some of these are given as follows −Event LogsThese stores the records of all the events that occur in the execution of a system. This is done so that the activities of all the events can be ... Read More