linux多核多进程访问文件示例程序(每个核上运行一个程序)

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/sysinfo.h>
#include <errno.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/stat.h>
#define __USE_GNU
#include <sched.h>
#include <ctype.h>
#include <string.h>
#include <pthread.h>

#define THREAD_MAX_NUM	100
int num;
void *threadWrite(void *arg)
{
cpu_set_t mask;
cpu_set_t get;
int *a = (int *)arg;
printf("the a is :%d\n",*a);
char buf2[]={"abcdefghijklmnopqrstuvwxyz"};  //要写入的信息
int fd2 = open("test",O_RDWR);               //打开要写入的文件
if(fd2 == -1)
{
printf("open failed\n");
return ;
}

printf("success fd = %d\n",fd2);
CPU_ZERO(&mask);                      //清零mask
CPU_SET(*a,&mask);                    //根据参出设置该进程运行在哪个核上(参数范围为0-3，因为有4个物理核)
if(sched_setaffinity(0,sizeof(mask),&mask)==-1)    //设定程序运行在哪个核上
{
printf("warning:could not set CPU affinity,continuing...\n");
}

CPU_ZERO(&get);
if(sched_getaffinity(0,sizeof(get),&get)==-1)              //读取在哪个核上运行的信息
{
printf("warning:could not get thread affinity,continuing...\n");
}
int i;
for(i=0;i<num;i++)
{
if(CPU_ISSET(i,&get))
{
printf("this thread %d is running processor:%d\n",i,i);
}
}
while(1)
{
pwrite(fd2,buf2,strlen(buf2),0);	//往文件中写入，pwrtie为可以设定偏移位置,也就可以保证文件的大小
sleep(1);
}
return NULL;
}
void *threadFun(void *arg)
{
cpu_set_t mask;
cpu_set_t get;
int *a = (int *)arg;
printf("the a is :%d\n",*a);
char buf1[1000];                  //保存读取内容缓冲区
int fd1 = open("vimrc_bak",O_RDWR);   //打开文件
if(fd1 == -1)
{
printf("open failed\n");
return ;
}

printf("success fd = %d\n",fd1);
CPU_ZERO(&mask);                  //同样时设置进程运行在哪个核上
CPU_SET(*a,&mask);

if(sched_setaffinity(0,sizeof(mask),&mask)==-1)
{
printf("warning:could not set CPU affinity,continuing...\n");
}

CPU_ZERO(&get);
if(sched_getaffinity(0,sizeof(get),&get)==-1)
{
printf("warning:could not get thread affinity,continuing...\n");
}
int i;
for(i=0;i<num;i++)
{
if(CPU_ISSET(i,&get))
{
printf("this thread %d is running processor:%d\n",i,i);
}
}
memset(buf1,0,sizeof(bu
4000
f1));
while(1)
{
if(read(fd1,buf1,sizeof(buf1))>0)        //持续赋取文件内容，当读取到文件尾时，在从头开始
{
printf("buf = %s\n",buf1);
memset(buf1,0,sizeof(buf1));
sleep(1);
}
else
{
lseek(fd1,0,SEEK_SET);
}

}
return NULL;
}

int main()
{
pthread_t thread[4];
int tid[4];
int i;

num = sysconf(_SC_NPROCESSORS_CONF);    //获取物理核的具体数
printf("system has %d processors\n",num);
for(i=0;i<2;i++)   //创建进程
{
tid[i] = i;
pthread_create(&thread[i],NULL,(void*)threadFun,(void*)&tid[i]);
}
for(i=2;i<4;i++)    //创建进程
{
tid[i] = i;
pthread_create(&thread[i],NULL,(void*)threadWrite,(void*)&tid[i]);
}
for(i=0;i<4;i++)   //等待进程运行完毕后再退出
{
pthread_join(thread[i],NULL);
}
return 0;
}