任务介绍 

在嵌入式Linux中创建四个进程，2个实时进程，2个非实时进程。每个进程中创建两个线程，在线程中调用系统服务来测试任务可中断睡眠、不可中断睡眠、暂停3中状态的切换，用一个 进程来测试进程退出过程。

任务要求： 1.说明进程创建与线程创建过程； 2.分别说明你在不同进程状态切换中使用的系统调用是哪种； 3.通过串口输出进程状态切换的打印信息，并截图插入作业报告中。

这篇文档已经过时了，建议转到我主页中的另一篇文章《嵌入式系统原理与应用——基于Linux和ARM笔记整理》，里面有该题更详细的讲解

导入所有库函数

#include<stdio.h>
#include<stdlib.h>
#include<assert.h>
#include<string.h>
#include<unistd.h>

#include<pthread.h>

定义进程，创建进程，打印进程的pid，打印进程的父进程

pid_t pid1,pid2,pid3,pid4;
        pid1=fork();
        printf("pid1:%d   ",getpid());
        printf("the return value:%d\n",pid1);

        pid2=fork();
        printf("pid2:%d   ",getpid());
        printf("the return value:%d\n",pid2);

        pid3=fork();
        printf("pid3:%d   ",getpid());
        printf("the return value:%d\n",pid3);

        pid4=fork();
        printf("pid4:%d   ",getpid());
        printf("the return value:%d\n",pid4);

修改进程的创建过程，实现创建两个实时进程，两个非实时进程

声明所有线程函数

//declare call thread function
void *fun1(void *);
void *fun2(void *);
void *fun3(void *);
void *fun4(void *);
void *fun5(void *);
void *fun6(void *);
void *fun7(void *);
void *fun8(void *);

每个进程中创建两个线程，即在某一句fork()后面进行输入

pid1=fork();
    pthread_t tid1,tid2;
    int ret = pthread_create(&tid1,NULL,fun1,NULL);
	if(ret != 0){
		perror("pthread_create");
		return -1;
	}
	//sleep(1);

	ret = pthread_create(&tid2,NULL,fun2,(void *)(long)a);
	if(ret != 0){
		perror("pthread_create");
		return -1;
	}

定义所有线程函数，先赋予每个线程打印自己tid号的功能

void *fun1(void *arg)
{
        printf("pthread_tid1 = %lu\n",(unsigned long)pthread_self());
}

void *fun2(void *arg)
{
        printf("pthread_tid2 = %lu\n",(unsigned long)pthread_self());
}

void *fun3(void *arg)
{
        printf("pthread_tid3 = %lu\n",(unsigned long)pthread_self());
}

void *fun4(void *arg)
{
        printf("pthread_tid4 = %lu\n",(unsigned long)pthread_self());
}

void *fun5(void *arg)
{
        printf("pthread_tid5 = %lu\n",(unsigned long)pthread_self());
}

void *fun6(void *arg)
{
        printf("pthread_tid6 = %lu\n",(unsigned long)pthread_self());
}

void *fun7(void *arg)
{
        printf("pthread_tid7 = %lu\n",(unsigned long)pthread_self());
}

void *fun8(void *arg)
{
        printf("pthread_tid8 = %lu\n",(unsigned long)pthread_self());
}

整合上半段任务的代码

#include<stdio.h>
#include<stdlib.h>
#include<assert.h>
#include<string.h>
#include<unistd.h>
#include<pthread.h>

//declare call thread function
void *fun1(void *);
void *fun2(void *);
void *fun3(void *);
void *fun4(void *);
void *fun5(void *);
void *fun6(void *);
void *fun7(void *);
void *fun8(void *);

int main(){
	pid_t pid1,pid2,pid3,pid4;
	int ret;
        pid1=fork();
        printf("pid1:%d   ",getpid());
        printf("the return value:%d\n",pid1);
	pthread_t tid1,tid2;
	ret = pthread_create(&tid1,NULL,fun1,NULL);
	ret = pthread_create(&tid2,NULL,fun2,NULL);

        pid2=fork();
        printf("pid2:%d   ",getpid());
        printf("the return value:%d\n",pid2);
	pthread_t tid3,tid4;
	ret = pthread_create(&tid3,NULL,fun3,NULL);
	ret = pthread_create(&tid4,NULL,fun4,NULL);

        pid3=fork();
        printf("pid3:%d   ",getpid());
        printf("the return value:%d\n",pid3);
	pthread_t tid5,tid6;
	ret = pthread_create(&tid5,NULL,fun5,NULL);
	ret = pthread_create(&tid6,NULL,fun6,NULL);

 
        pid4=fork();
        printf("pid4:%d   ",getpid());
        printf("the return value:%d\n",pid4);
	pthread_t tid7,tid8;
	ret = pthread_create(&tid7,NULL,fun7,NULL);
	ret = pthread_create(&tid8,NULL,fun8,NULL);


	while(1){}
	return 0;
}

void *fun1(void *arg)
{
        printf("pthread_tid1 = %lu\n",(unsigned long)pthread_self());
	pthread_exit(NULL);
}
 
void *fun2(void *arg)
{
        printf("pthread_tid2 = %lu\n",(unsigned long)pthread_self());
	pthread_exit(NULL);
}
 
void *fun3(void *arg)
{
        printf("pthread_tid3 = %lu\n",(unsigned long)pthread_self());
	pthread_exit(NULL);
}
 
void *fun4(void *arg)
{
        printf("pthread_tid4 = %lu\n",(unsigned long)pthread_self());
	pthread_exit(NULL);
}
 
void *fun5(void *arg)
{
        printf("pthread_tid5 = %lu\n",(unsigned long)pthread_self());
	pthread_exit(NULL);
}
 
void *fun6(void *arg)
{
        printf("pthread_tid6 = %lu\n",(unsigned long)pthread_self());
	pthread_exit(NULL);
}
 
void *fun7(void *arg)
{
        printf("pthread_tid7 = %lu\n",(unsigned long)pthread_self());
	pthread_exit(NULL);
}
 
void *fun8(void *arg)
{
        printf("pthread_tid8 = %lu\n",(unsigned long)pthread_self());
	pthread_exit(NULL);s
}

在终端的运行结果

修改函数内部，实现在线程中调用系统服务来测试任务可中断睡眠、不可中断睡眠、暂停3中状态的切换

1. "任务可中断睡眠"指进程进入睡眠状态，可以被外部中断唤醒。在 Linux 系统中，可以使用 sleep 或 usleep 系统调用来实现可中断睡眠。例如，sleep(5) 表示进程睡眠 5 秒钟。如果在睡眠期间接收到信号，进程会被唤醒。

2. "任务不可中断睡眠"指进程进入睡眠状态，无法被外部中断唤醒。在 Linux 系统中，可以使用 pause 系统调用来实现不可中断睡眠。进程会一直睡眠，直到接收到一个信号。通常，用于等待信号的时候会使用 pause 函数。

3. "任务暂停"指进程的执行被暂停，直到接收到某个特定的信号。在 Linux 系统中，可以使用 pause 或 sigsuspend 系统调用来实现任务暂停。调用这些函数后，进程将一直等待，直到接收到一个指定的信号才会继续执行。

void *fun1(void *arg)
{
    printf("pthread_tid1 = %lu\n",(unsigned long)pthread_self());

    while(1)
    {
        // 任务可中断睡眠
        sleep(1);  //休眠一秒

        printf("fun1: Task is awake\n");
    }
}

void *fun2(void *arg)
{
    printf("pthread_tid2 = %lu\n",(unsigned long)pthread_self());

    while(1)
    {
        // 任务不可中断睡眠
        pause();

        printf("fun2: Task is awake\n");
    }
}

休眠1秒时，tid1比tid2先创建

休眠5秒时，tid2比tid1先创建

用一个进程来测试进程退出过程。首先用命令ps -ef找到要杀死的线程，然后再kill。可以在进程中看到“Terminated”，说明成功退出