Three basic state of the process

 Three states: 

1.     Ready 
2.     carried out
3.     Clog

Switching between the three states

 

 

 

FIG. I / O into file I / O, network I / O

There are I / O there is obstruction, here is the starting point for computer optimization, network optimization solution of IO models is simply here.

 

ps:

PCB:

 

Process control block (PCB) data structure is a specialized system for the setting management process. The system used to record external features which process, during motion of the process described. At the same time, the system can use PCB to control and manage the process, so that, PCB (process control block) is the only sign of the presence of system-aware process.
 PCB Linux systems include a number of parameters, each PCB accounting for more than 1KB of memory space