1.Describe Life cycle of Process



The process may in one of the following state in its life cycle：

New：being created.

Running:being excuted.

Waiting:waiting for some event or occur.

Reday:waiting to be assigned to a processor.

Terminated:finished excution.

 

2.Why PCB

Process contorl block contains many pieces of information associated with a specific process,include process state,program counter,CPU registers,CPU scheduling information,memory management information,accounting information and I/O status information.
It is part of the process entity and is the most important recorded data structure in the operating system. It is the most important data structure for process management and control.