linux线程绑定

不管是线程还是进程，都是通过设置亲和性(affinity)来达到目的。

    与进程的情况相似，线程亲和性的设置和获取主要通过下面两个函数来实现：

int pthread_setaffinity_np(pthread_tthread, size_t cpusetsize，const cpu_set_t *cpuset);

int pthread_getaffinity_np(pthread_t thread, size_t cpusetsize, cpu_set_t *cpuset);

    从函数名以及参数名都很明了，唯一需要点解释下的可能就是cpu_set_t这个结构体了。这个结构体的理解类似于select中的fd_set，可以理解为cpu集，也是通过约定好的宏来进行清除、设置以及判断：

//初始化，设为空
void CPU_ZERO (cpu_set_t *set);
//将某个cpu加入cpu集中
void CPU_SET (int cpu, cpu_set_t *set);
//将某个cpu从cpu集中移出
void CPU_CLR (int cpu, cpu_set_t *set);
//判断某个cpu是否已在cpu集中设置了
int CPU_ISSET (int cpu, const cpu_set_t *set);

cpu集可以认为是一个掩码，每个设置的位都对应一个可以合法调度的 cpu，而未设置的位则对应一个不可调度的 CPU。换而言之，线程都被绑定了，只能在那些对应位被设置了的处理器上运行。通常，掩码中的所有位都被置位了，也就是可以在所有的cpu中调度。       

使用函数pthread_attr_setaffinity_np

 

#include <stdio.h>
#include <pthread.h>
#include <unistd.h>

int GetCpuCount()
{
    return (int)sysconf(_SC_NPROCESSORS_ONLN);
}

void *thread_fun()
{
    int i;
    while(1)
    {
        i = 0;
    }

    return NULL;
}

int main()
{
    int cpu_num = 0;
    cpu_num  = GetCpuCount();
    printf("The number of cpu is %d\n", cpu_num);

    pthread_t t1;
    pthread_t t2;
    pthread_attr_t attr1;
    pthread_attr_t attr2;

    pthread_attr_init(&attr1);
    pthread_attr_init(&attr2);

    cpu_set_t cpu_info;
    __CPU_ZERO(&cpu_info);
    __CPU_SET(0, &cpu_info);
    if (0!=pthread_attr_setaffinity_np(&attr1, sizeof(cpu_set_t), &cpu_info))
    {
        printf("set affinity failed");
        return;
    }

    __CPU_ZERO(&cpu_info);
    __CPU_SET(1, &cpu_info);
    if (0!=pthread_attr_setaffinity_np(&attr2, sizeof(cpu_set_t), &cpu_info))
    {
        printf("set affinity failed");
    }

    if (0!=pthread_create(&t1, &attr1, thread_fun, NULL))
    {
        printf("create thread 1 error\n");
        return;
    }

    if (0!=pthread_create(&t2, &attr2, thread_fun, NULL))
    {
        printf("create thread 2 error\n");
        return;
    }

    pthread_join(t1, NULL);
    pthread_join(t2, NULL);
}

 

使用函数pthread_setaffinity_np

 

#include <stdio.h>
#include <pthread.h>
#include <unistd.h>

int GetCpuCount()
{
    return (int)sysconf(_SC_NPROCESSORS_ONLN);
}

void *thread_fun()
{
    int i;
    while(1)
    {
        i = 0;
    }

    return NULL;
}

int main()
{
    int cpu_num = 0;
    cpu_num  = GetCpuCount();
    printf("The number of cpu is %d\n", cpu_num);

    pthread_t t1;
    pthread_t t2;
    pthread_attr_t attr1;
    pthread_attr_t attr2;

    pthread_attr_init(&attr1);
    pthread_attr_init(&attr2);

    if (0!=pthread_create(&t1, &attr1, thread_fun, NULL))
    {
        printf("create thread 1 error\n");
        return;
    }

    if (0!=pthread_create(&t2, &attr2, thread_fun, NULL))
    {
        printf("create thread 2 error\n");
        return;
    }

    cpu_set_t cpu_info;
    __CPU_ZERO(&cpu_info);
    __CPU_SET(0, &cpu_info);
    if (0!=pthread_setaffinity_np(t1, sizeof(cpu_set_t), &cpu_info))
    {
        printf("set affinity failed");
    }

    __CPU_ZERO(&cpu_info);
    __CPU_SET(1, &cpu_info);
    if (0!=pthread_setaffinity_np(t2, sizeof(cpu_set_t), &cpu_info))
    {
        printf("set affinity failed");
    }

    pthread_join(t1, NULL);
    pthread_join(t2, NULL);
}