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What is process control block in operating system?
All of the information needed to keep track of a process when switching is kept in a data package called process control block.s A PCB is a data structure in the operating system kernel containing the information needed to manage a particular process. The PCB is the manifestation of a process in an operating system,
What is the content PCB in operating system?
A Process Control Block (PCB, also called Task Controlling Block or Task Struct) is a data structure in the operating system kernel containing the information needed to manage a particular process. The PCB is "the manifestation of a process in an operating system".[1]Included informationImplementations differ, but in general a PCB will include, directly or indirectly:The identifier of the process (a process identifier, or PID)Register values for the process including, notably, the program counter and stack pointer values for the process.The address space for the processPriority (in which higher priority process gets first preference. eg., nice value on Unix operating systems)Process accounting information, such as when the process was last run, how much CPU time it has accumulated, etc.Pointer to the next PCB i.e. pointer to the PCB of the next process to runI/O Information (i.e. I/O devices allocated to this process, list of opened files, etc)During context switch, the running process is stopped and another process is given a chance to run. The kernel must stop the execution of the running process, copy out the values in hardware registers to its PCB, and update the hardware registers with the values from the PCB of the new process.
What is the function of process control block?
A process in an operating system is represented by a data structure known as a process control block (PCB) or process descriptor. The PCB contains important information about the specific process includingThe current state of the process i.e., whether it is ready, running, waiting, or whatever.Unique identification of the process in order to track "which is which" information.A pointer to parent process.Similarly, a pointer to child process (if it exists).The priority of process (a part of CPU scheduling information).Pointers to locate memory of processes.A register save area.The processor it is running on.The PCB is a certain store that allows the operating systems to locate key information about a process. Thus, the PCB is the data structure that defines a process to the operating systems.
What are the typical elements of a process image?
User data: Modifiable part of user space. May include program data, user stack area, and programs that may be modified.User program: The instructions to be executed.System Stack: Each process has one or more LIFO stacks associated with it. Used to store parameters and calling addresses for procedure and system calls.Process control Block (PCB): Info needed by the OS to control processes.
Three major complications that concurrent processing adds to an operating system?
1. The OS has to keep track of the main memory address space allocated to each process so that a process does not affect or harm other processes data. This is a necessay , for example, a virus may try to destroy or modify other process data. 2. Switching from one process to another process leads to time overhead, this requires storing the current register values and loading the register values of the next process from its PCB(program Control Block). 3. If a running process requires large space in memory then other processs needs to be dumped back to hard disk which again leads to time overhead. For more information mail to: akhilanger@gmail.com
