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Measuring efficiency of Mutex and Busy waiting
void *incr(void *tid)
{
    int i;
    for(i = 0; i < 10000; i++)
    {
        pthread_mutex_lock(&the_mutex);     //Grab the lock
        sharedVar++;    //Increment the shared variable
        pthread_mutex_unlock(&the_mutex);   //Release the lock
    }
    pthread_exit(0);
}

void *incr(void *tid)
{
    int i;
    for(i = 0; i < 10000; i++)
    {
        enter_region((int)tid);  //Grab the lock
        sharedVar++;        //Increment the shared variable
        leave_region((int)tid);  //Release the lock
    }
    pthread_exit(0);
}
void enter_region(int tid)
{
    interested[tid] = true;     //Show this thread is interested
    turn = tid;     //Set flag
    while(turn == tid && other_interested(tid));    //Busy waiting
}
bool other_interested(int tid)    //interested[] is initialized to all false
{
    int i;
    for(i = 0; i < tNumber; i++)
        if(i != tid)
            if(interested[i] == true)   //There are other threads that are interested
                return true;
    return false;
}
void leave_region(int tid)
{
    interested[tid] = false;    //Depart from critical region
}

if (check[sharedVar]) cout << "ERROR" << endl;
else check[sharedVar++] = true;

interested[tid] = true;     //Show this thread is interested
turn = tid;     //Set flag
while(turn == tid && other_interested(tid));

while( compare_and_swap_atomic(myid,id_meaning_it_is_free) == false);