为了加快程序的运行速度和充分利用CPU资源，我们可以人为将不同线程绑定在不同的cup上，例如有两个线程A,B，其中A已经在CPU0上运行，并且CPU0上还有其他的任务，那么我们可以将线程B绑到CPU1上，这样就可以减轻CPU0的负担，从而充分利用多核CPU。原来是一个CPU做两件事，现在两个CPU同时做两个事，使效率更高。

看下下面的代码

#define _GNU_SOURCE
#include <sched.h>      //这两个头文件是一起的#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <pthread.h>void *myfun(void *arg)
{cpu_set_t mask;cpu_set_t get;CPU_ZERO(&mask);CPU_SET(1, &mask);if (pthread_setaffinity_np(pthread_self(), sizeof(mask), &mask) < 0) {fprintf(stderr, "set thread affinity failed\n");}CPU_ZERO(&get);if (pthread_getaffinity_np(pthread_self(), sizeof(get), &get) < 0) {fprintf(stderr, "get thread affinity failed\n");}if (CPU_ISSET(1, &get)) {printf("thread %lu is running in processor 1\n", (long unsigned)pthread_self());}pthread_exit(NULL);     //退出线程
}int main(int argc, char *argv[])
{pthread_t tid;          //用来创建新的线程cpu_set_t mask;         //用来设置cpu_set_t get;          //用来获int num = sysconf(_SC_NPROCESSORS_CONF);    //获取CPU核数printf("system has %d processor(s)\n", num);if (pthread_create(&tid, NULL, (void *)myfun, NULL) != 0)    //创建线程  myfun为入口函数{fprintf(stderr, "thread create failed\n");return -1;}CPU_ZERO(&mask);            //初始化某个CPU集，设置为空CPU_SET(0, &mask);          //将某个CPU加入到这个CPU集合里，这里是，也可以理解为，绑定CPU，这里是CPU0if (pthread_setaffinity_np(pthread_self(), sizeof(mask), &mask) < 0)       //pthread_self()：获得线程自身ID{                                                                       //设置某一线程运行在某个CPU上fprintf(stderr, "set thread affinity failed\n");}CPU_ZERO(&get);if (pthread_getaffinity_np(pthread_self(), sizeof(get), &get) < 0) {                                                                       //查看某一个CPU上有哪些线程fprintf(stderr, "get thread affinity failed\n");}if (CPU_ISSET(0, &get)) {                                               //判断某个CPU是不是在CPU集里，这里为CPU0printf("thread %lu is running in processor 0\n", (long unsigned)pthread_self());}pthread_join(tid, NULL);    //等待线程return 0;
}

 编译一下

gcc cpu.c -pthread

thread 139946778752832 is running in processor 0
thread 139946770462464 is running in processor 1

可以看到我们将两个线程分别绑在了不同的CPU上面。

这里总结一下用到的基本函数：

void CPU_ZERO (cpu_set_t *set);   //初始化，设为空void CPU_SET (int cpu, cpu_set_t *set); //将某个cpu加入cpu集中 void CPU_CLR (int cpu, cpu_set_t *set); //将某个cpu从cpu集中移出 int CPU_ISSET (int cpu, const cpu_set_t *set); //判断某个cpu是否已在cpu集中设置了int pthread_setaffinity_np(pthread_t thread,size_t cpusetsize,const cpu_set_t *cpuset); //设置CPUint pthread_getaffinity_np(pthread_t thread,size_t cpusetsize, cpu_set_t *cpuset); //查看CPU