Multi-Task programming

Conversation-level multitasking

process-level multi-tasking

A process is a running program

pid_t getpid ();//Return to the current process PID

pid_t getppid ();//return parent process PID

A task_struct struct is a unique indicator of a process's existence, the process control block. Pcb

struct Task_struct *task[512] ={&init_task}; Array of pointers

PID Hash array helps manage process PID

Fork (); Create a new process

#include <unistd.h>

pit_t fork (void);

function return value: The PID number of the child process that was created in the parent process is returned, 0 is returned in the child process, and the creation failure returns-1

Multi-tasking at the thread level

Multi-Task programming