Read the Linux kernel and understand these things.

The Linux kernel understands these things-general Linux technology-Linux programming and kernel information. The following is a detailed description. I don't know whether to understand it or not. Just write it down first, as long as you don't mislead others.

Scheduling of processes in Linux:
When a user calls a system call in a process, the kernel will continue to execute the user process through the system call handler. When the system call returns from the kernel, the kernel first calls the scheduling function to schedule user processes;

If the user process is always in the computing state, that is, if the system call is not called, the kernel suspends the user process and executes the interrupt processing program when the user process is interrupted, after the interrupt processing program is executed, the kernel calls the scheduling function to determine whether to schedule the program.

The current understanding is probably like this, and the specific details are still to be read.