The process control block is part of the process entity and is the most important record-type data structure in the operating system. The PCB records all the information needed by the operating system to describe the process and control the process. The role of the process control block is to make a program (including data) that cannot be independently executed in a multi-program environment, become a basic unit that can run independently, and a process that can be executed concurrently with other processes. In other words, the operating system controls and manages the concurrent execution process according to the PCB.
In the process control block, it mainly includes four aspects.
(1) Process identifier information. The process identifier is used to uniquely identify a process. A process usually has the following two identifiers: an external identifier, an internal identifier.
(2) Processor status information. The composition processor status information is mainly composed of the contents of various registers of the processor.
(3) Process-scheduling information. Some information related to process scheduling and process swapping is also stored in the PCB, including: process status, process priority, other information required for process scheduling, and events.
(4) Process control information. Process control information includes: address of programs and data, process synchronization and communication mechanisms, resource lists, and link pointers.
3. PCB organization
In a system, there are usually dozens, hundreds, or even thousands of PCBs(Multilayer pcb manufacturer china). In order to effectively manage them, they should be organized in an appropriate way. Currently, there are two common ways to organize them. Ways and indexing methods.