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Task Control Block)
A Process Control Block (PCB, also called Task Control 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]
[edit] Included information
Implementations 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 value for the process
- The address space for the process
- priority
- A list of open files & sockets
- 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 run
During a 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.
[edit] Location of the PCB
Since the PCB contains the critical information for the process, it must be kept in an area of memory protected from normal user access. In some operating systems the PCB is placed in the beginning of the kernel stack of the process since that is a convenient protected location. [2]
TCB 는 어디에 저장되는지 궁금해서 아는 행님한티 물어보니 가르쳐준거
http://en.wikipedia.org/wiki/Task_Control_Block
결론적으로는 PCB 동일하게 일반 유저의 접근으로부터 보호되는 메모리 영역에서 유지되는 커널스택에 유지되게 되는것. 한마디로 커널이 사용하는 메모리 공간이라는 것.
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