Explain process control block

Answer 1

The Process Control Block acts as a library of information about the processes in a system. Specific information is stored in the process control block highlighting important information about each process.

Answer 2

PCB or Process Control Block stores information about a process. A process has various related information, such as registers, counters, states, identifiers, memory pointers, etc.PCB is an important block that helps OS in performing multiple processes and also allows multi-processing. PCB stores enough information, which is useful when an interrupt occurs; using the information present in PCB, the process can begin again from the last state as if nothing had happened to it.

PCB is present in a process table, i.e., a process table contains all the PCBs of the processes running in the operating system. Whenever a new process is created, the operating system creates a new PCB and initializes it with the appropriate information.

The PCB contains various data fields for a process, namely:

Process ID: Whenever a new process is created, the Operating system assigns it a unique id. A process in memory is recognized by its unique process id.

Process State: This field depicts the state of a process. A process in memory can be in various states, like ready, running, waiting, or terminated.

Program Counter: This is the most important field, which contains information about the next instruction to be performed for the process.

Process Priority: Priority is a number assigned to every process; this number shows the importance of one process over the other. The higher this number, the smaller its priority.

CPU registers: CPU registers store the values of the processor registers for the process. The registers are stored in RAM(virtual memory).

Memory Address: Every process is assigned a memory address.PCB stores the base memory address and limit of every process's memory space.

Input/Output Operation: This field stores information about the state of the process, i.e., whether it is waiting for I/O operations to complete or not.

PCB pointer: This pointer has the address to the next process control block, which is in the ready state. It helps in easy navigation between the processes.

Linked Lists are used for implementing Process Control Blocks. The Process tables help in locating the corresponding PCB. During a context switching, the Operating System uses the Process table to retrieve the PCB by using the corresponding Process ID.

Hence, PCB plays an important role in managing the processes and allowing the operating system to keep track of the process state and resources used by them.It also ensures that multiple processes can run simultaneously on the system without any disturbance between them.

Answer 3

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