Linux编程之《进程/线程绑定CPU》

Intro
-----

通常我们在编写服务器代码时，可以通过将当前进程绑定到固定的CPU核心或者线程绑定到固定的CPU核心来提高系统调度程序的效率来提高程序执行的效率，下面将完整代码贴上。

 /************************************************
  * 该例程讲解了进程、线程绑定到固定的cpu核心上运行
  * 来提高程序运行效率
 ************************************************/
 #include <unistd.h>
 #ifndef __USE_GNU
 #define __USE_GNU   // 为了使用SET_SET()等宏定义，但unistd.h里面好像已经定义了
 #endif
 #include <sched.h>
 #include <pthread.h>
 #include <stdio.h>
 #include <vector>

 unsigned int systemCPUNum()
 {
     // _SC_NPROCESSORS_CONF的值为CPU个数，基于0开始编号
     return sysconf(_SC_NPROCESSORS_CONF);
 }

 bool currentProcessAffinity(std::vector<unsigned int>& runningCPUVector)
 {
     cpu_set_t cpuSet;

     // 清空一个CPU集合
     CPU_ZERO(&cpuSet);

     // 得到指定进程ID绑定到哪个CPU
     int ret = sched_getaffinity(, // 0代表当前进程
                                sizeof(cpuSet),
                                &cpuSet);
     if (ret < )
     {
         return false;
     }

     unsigned int cpuNum = systemCPUNum();
     runningCPUVector.clear();
     for (unsigned int i = ; i < cpuNum; ++i)
     {
         // 检查一个CPU号是否在一个集合中
         if (CPU_ISSET(i, &cpuSet))
         {
             runningCPUVector.push_back(i);
         }
     }

     return true;
 }

 bool setCurrentProcessAffinity(const std::vector<unsigned int>& needBindCPUVector)
 {
     cpu_set_t cpuSet;

     // 清空一个CPU集合
     CPU_ZERO(&cpuSet);

     for (auto& iter : needBindCPUVector)
     {
         CPU_SET(iter, &cpuSet);
     }

     // 将指定进程ID绑定到CPU
     int ret = sched_setaffinity(, // 0代表当前进程
                                sizeof(cpuSet),
                                &cpuSet);
     if (ret < )
     {
         return false;
     }

     return true;
 }

 bool currentThreadAffinity(std::vector<unsigned int>& runningCPUVector)
 {
     cpu_set_t cpuSet;

     // 清空一个CPU集合
     CPU_ZERO(&cpuSet);

     // 得到指定线程ID绑定到哪个CPU
     int ret = pthread_getaffinity_np(pthread_self(),
                                      sizeof(cpuSet),
                                      &cpuSet);
     if (ret < )
     {
         return false;
     }

     unsigned int cpuNum = systemCPUNum();
     runningCPUVector.clear();
     for (unsigned int i = ; i < cpuNum; ++i)
     {
         // 检查一个CPU号是否在一个集合中
         if (CPU_ISSET(i, &cpuSet))
         {
             runningCPUVector.push_back(i);
         }
     }

     return true;
 }

 bool setCurrentThreadAffinity(const std::vector<unsigned int>& needBindCPUVector)
 {
     cpu_set_t cpuSet;

     // 清空一个CPU集合
     CPU_ZERO(&cpuSet);

     for (auto& iter : needBindCPUVector)
     {
         CPU_SET(iter, &cpuSet);
     }

     // 将指定线程ID绑定到CPU
     int ret = pthread_setaffinity_np(pthread_self(),
                                      sizeof(cpuSet),
                                      &cpuSet);
     if (ret < )
     {
         return false;
     }

     return true;
 }

 int main()
 {
     printf("*****Process bind CPU sample*****\n");
     unsigned int cpuNum = systemCPUNum();
     printf("Current system has %u CPU(s)\n", cpuNum);

     std::vector<unsigned int> runningCPUVector;
     if (!currentProcessAffinity(runningCPUVector))
     {
         printf("Get current process was bound witch CPU failed\n");
         return ;
     }

     for (auto& iter : runningCPUVector)
     {
         printf("Current process is running at %u CPU\n", iter);
     }

     std::vector<unsigned int> needBindCPUVector {, };
     if (!setCurrentProcessAffinity(needBindCPUVector))
     {
         printf("Current process bind CPU failed\n");
         return ;
     }

     printf("Current process bind CPU success\n");

     runningCPUVector.clear();
     if (!currentProcessAffinity(runningCPUVector))
     {
         printf("Get current process was bound witch CPU failed\n");
         return ;
     }

     for (auto& iter : runningCPUVector)
     {
         printf("Current process is running at %u CPU\n", iter);
     }

     printf("\n*****Thread bind CPU sample*****\n");
     runningCPUVector.clear();
     if (!currentThreadAffinity(runningCPUVector))
     {
         printf("Get current thread was bound witch CPU failed\n");
         return ;
     }

     for (auto& iter : runningCPUVector)
     {
         printf("Thread %lu is running at %u CPU\n", pthread_self(), iter);
     }

     needBindCPUVector.clear();
     needBindCPUVector.push_back();
     if (!setCurrentThreadAffinity(needBindCPUVector))
     {
         printf("Current thread bind CPU failed\n");
         return ;
     }

     printf("Thread %lu bind CPU success\n", pthread_self());

     runningCPUVector.clear();
     if (!currentThreadAffinity(runningCPUVector))
     {
         printf("Get current thread was bound witch CPU failed\n");
         return ;
     }

     for (auto& iter : runningCPUVector)
     {
         printf("Thread %lu is running at %u CPU\n", pthread_self(), iter);
     }

     return ;
 }

程序执行的输出结果：
*****Process bind CPU sample*****
Current system has 4 CPU(s)
Current process is running at 0 CPU
Current process is running at 1 CPU
Current process is running at 2 CPU
Current process is running at 3 CPU
Current process bind CPU success
Current process is running at 0 CPU
Current process is running at 2 CPU

*****Thread bind CPU sample*****
Thread 139871129114432 is running at 0 CPU
Thread 139871129114432 is running at 2 CPU
Thread 139871129114432 bind CPU success
Thread 139871129114432 is running at 1 CPU

该例子的github地址：https://github.com/chxuan/samples/blob/master/BindCPU/BindCPU.cpp