I have implemented a lock free linked list data structure. I am trying to measure the time taken by the program. I have 4 threads. The threads are implemented using pthreads library. Currently I am measuring the time using the following method
#include <time.h>
/*
Some code
.........
*/
pthread_t t1,t2;
clock_t begin = clock();
pthread_create (&t1, NULL, thread1, (void *)mylist);
pthread_create (&t2, NULL, thread2, (void *)mylist);
pthread_create (&t3, NULL, thread3, (void *)mylist);
pthread_create (&t4, NULL, thread4, (void *)mylist);
pthread_join (t1, NULL);
pthread_join (t2, NULL);
pthread_join (t3, NULL);
pthread_join (t4, NULL);
clock_t end= clock();
double time_s = (double)(end-begin)/ CLOCKS_PER_SEC;
I thought that this would give me correct result. However when I measured time taken to individual threads like this
void * thread1(void * args)
{
clock_t begin = clock();
/* Some Code */
clock_t end= clock();
double time_s = (double)(end-begin)/ CLOCKS_PER_SEC;
}
The timing was different. These are the reading that I got:
Total time:
2.06341
Thread 1
Time: 0.767887
Thread 2
Time:1.20169
Thread 3
Time:1.92999
Thread 4
Time:2.0584
Why is this happening? Is this correct? Any help would be appreciated.
