多核环境下cache line的测试

  1 #define EXEC_COUNT (100 * 1000 * 1000)
  2  
  3 struct bits_t
  4 {
  5     int a;
  6     char placeholder[64];
  7     int b;
  8 };
  9  
 10 struct bits_t bits;
 11  
 12 int which_cpu(const char* prefix_)
 13 {
 14     #ifdef ENABLE_WHCIH_CPU
 15     cpu_set_t cur_cpu;
 16     CPU_ZERO(&cur_cpu);
 17     if (sched_getaffinity(0, sizeof(cur_cpu), &cur_cpu) == -1)
 18     {
 19         printf("warning: cound not get cpu affinity, continuing...\n");
 20         return -1;
 21     }
 22     int num = sysconf(_SC_NPROCESSORS_CONF);
 23     for (int i = 0; i < num; i++)
 24     {
 25         if (CPU_ISSET(i, &cur_cpu))
 26         {
 27             printf("[%s] this process %d is running processor : %d\n", prefix_, getpid(), i);
 28         }
 29     }
 30     #endif
 31  
 32     return 0;
 33 }
 34  
 35 int set_cpu(int cpu_id_)
 36 {
 37     #ifdef ENABLE_SET_CPU
 38     cpu_set_t mask;
 39     CPU_ZERO(&mask);
 40     CPU_SET(cpu_id_, &mask);
 41     if (sched_setaffinity(0, sizeof(mask), &mask) == -1)
 42     {
 43         printf("warning: could not set CPU affinity, continuing...\n");
 44         return -1;
 45     }
 46     #endif
 47  
 48     return 0;
 49 }
 50  
 51 void* thd_func1(void* arg_)
 52 {
 53     set_cpu(0);
 54     which_cpu("thread 1 start");
 55     timeval begin_tv;
 56     gettimeofday(&begin_tv, NULL);
 57  
 58     for (int i = 0; i < EXEC_COUNT; i++)
 59     {
 60         bits.a += 1;
 61         int a = bits.a;
 62     }
 63  
 64     timeval end_tv;
 65     gettimeofday(&end_tv, NULL);
 66     printf("thd1 perf:[%lu]us\n", (end_tv.tv_sec * 1000 * 1000 + end_tv.tv_usec) - (begin_tv.tv_sec * 1000 * 1000 + begin_tv.tv_usec));
 67     which_cpu("thread 1 end");
 68  
 69     return NULL;
 70 }
 71  
 72 void* thd_func2(void* arg_)
 73 {
 74     set_cpu(1);
 75     which_cpu("thread 2 start");
 76     timeval begin_tv;
 77     gettimeofday(&begin_tv, NULL);
 78  
 79     for (int i = 0; i < EXEC_COUNT; i++)
 80     {
 81         bits.b += 2;
 82         int b = bits.b;
 83     }
 84  
 85     timeval end_tv;
 86     gettimeofday(&end_tv, NULL);
 87     printf("thd2 perf:[%lu]us\n", (end_tv.tv_sec * 1000 * 1000 + end_tv.tv_usec) - (begin_tv.tv_sec * 1000 * 1000 + begin_tv.tv_usec));
 88     which_cpu("thread 2 end");
 89  
 90     return NULL;
 91 }
 92  
 93 int main(int argc_, char* argv_[])
 94 {
 95     int num = sysconf(_SC_NPROCESSORS_CONF);
 96     printf("system has %d processor(s).\n", num);
 97     cpu_set_t cpu_mask;
 98     cpu_set_t cur_cpu_info;
 99  
100     memset((void*)&bits, 0, sizeof(bits_t));
101     set_cpu(0);
102     which_cpu("main thread");
103  
104     pthread_t pid1;
105     pthread_create(&pid1, NULL, thd_func1, NULL);
106  
107     pthread_t pid2;
108     pthread_create(&pid2, NULL, thd_func2, NULL);
109  
110     pthread_join(pid1, NULL);
111     pthread_join(pid2, NULL);
112  
113     return 0;
114 }