Summary of process-related knowledge points
process definition
Definition : A program that runs is a process. A process is an important software resource that is created byoperating system kernelresponsible for management.
PCB: Process Control Block
PCB: a structure used to describe the process
Replenish:passDoubly linked listTo connect multiple PCBs together (the linked list here is not a simple doubly linked list).
pid: process identifier (unique number)
memory pointer
Memory pointer: Used to explain what your own memory is.
file descriptor table
File descriptor table: files and other resources on the hard disk.
The memory pointer and the file descriptor table together describe which hardware resources the process holds.
Process scheduling related properties
The essence of process scheduling is to solve the problem of "more wolves and less meat", so that a large number of processes can be carried out simultaneously on a small number of CPUs。
process state
- Ready state : On call, the process is ready to execute on the CPU at any time.
- Running status : running on the CPU.
- Blocked state : It cannot be executed on the CPU for a short time. For example, the process is performing intensive IO operations, reading and writing data.
priority
Processes are prioritized . The process scheduling of the operating system is not a bowl of water.
the context
- When the operating system performs process switching, it needs to record and save the intermediate state of the process execution. The next time the process runs on the CPU, it can restore the last state and continue to execute.
- The process context isThe value of each register in the CPU。
virtual address space
The virtual address space of the process solves the problem of mutual influence between processes .Introduce a virtual address space, and the address can be found in time if the address crosses the boundary。
interprocess communication
The data interaction between processes is completed through the public space . Use files, use the network.