Process control block (PCB)
To implement the process model, the operating system maintains a table, an array of structures, called the process table or process control block (PCB) or Switch frame. Each entry identifies a process with information such as process state, its program counter, stack pointer, memory allocation, the status of its open files, its accounting and scheduling information. In other words, it must contain everything about the process that must be saved when the process is switched from the running state to the ready state so that it can be restarted later as if it had never been stopped. The following is the information stored in a PCB.
• Process state, which may be new, ready, running, waiting or halted;
• Process number, each process is identified by its process number, called process ID;
• Program counter, which indicates the address of the next instruction to be executed for this process;
• CPU registers, which vary in number and type, depending on the concrete microprocessor architecture;
• Memory management information, which include base and bounds registers or page table;
• I/O status information, composed I/O requests, I/O devices allocated to this process, a list of open files and so on;
• Processor scheduling information, which includes process priority, pointers to scheduling queues and any other scheduling parameters;
• List of open files.
A process structure block is shown in Figure
Process Control Block
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its really helpful to me…..