Profiling cache misses for separate pthread using PAPI

I am trying to investigate the performance of my program, whereas cache misses is a huge bottleneck. For testing purposes, before implementing PAPI in to the target application, I needed to verify how stuff works, which is why I posted a sample program.

My intention is to use PAPI for monitoring the cache misses of a separate thread. I am trying to use the PAPI_attach to apply my event sets to the specific thread ID, however, the cache misses which I measure are still the same (or at least VERY similar) for when not using the PAPI_attach.

Another experiment I did to verify my concerns was to start the Firefox browser during a run of this very simple program. This let to an increased amount of measured cache misses, so obviously, something is very strange regarding the PAPI_attach function and how I am using it.

Using the below code for my thread worker:

void * Slave(void * args)
{

   int rc = 0;
   int tmp, i, j;
   /*must be initialized to PAPI_NULL before calling PAPI_create_event*/
   int EventSet = PAPI_NULL;
   long long values[NUM_EVENTS];
   /*This is where we store the values we read from the eventset */

   /* We use number to keep track of the number of events in the EventSet */ 
   int retval, number;


   pid_t tid;
   tid = syscall(SYS_gettid);

   char errstring[PAPI_MAX_STR_LEN];

   /* get the number of events in the event set */
   number = 0;

   printf("My pid is: %d\n", tid);

   if ( (retval=PAPI_register_thread())!= PAPI_OK )
       ERROR_RETURN(retval);

   if ( (retval = PAPI_create_eventset(&EventSet)) != PAPI_OK)
      ERROR_RETURN(retval);

   /* Add Total Instructions Executed to the EventSet */
   if ( (retval = PAPI_add_event(EventSet, PAPI_L1_TCM)) != PAPI_OK)
      ERROR_RETURN(retval);

   /* Add Total Cycles event to the EventSet */
   if ( (retval = PAPI_add_event(EventSet, PAPI_L2_TCM)) != PAPI_OK)
      ERROR_RETURN(retval);

   if ( (retval = PAPI_add_event(EventSet, PAPI_L3_TCM)) != PAPI_OK)
      ERROR_RETURN(retval);

   number = 0;
   if ( (retval = PAPI_list_events(EventSet, NULL, &number)) != PAPI_OK)
      ERROR_RETURN(retval);

   printf("There are %d events in the event set\n", (unsigned int)number);

   if ((retval = PAPI_attach(EventSet, tid)) != PAPI_OK)
      ERROR_RETURN(retval);
   /* Start counting */

   if ( (retval = PAPI_start(EventSet)) != PAPI_OK)
      ERROR_RETURN(retval);

   /* you can replace your code here */

   tmp=0;
   for (i = 0; i < 200000000; i++)
   {
      tmp = i + tmp;
   }

   if ( (retval=PAPI_read(EventSet, values)) != PAPI_OK)
      ERROR_RETURN(retval);

   printf("L1 misses %lld \n", values[0] );
   printf("L2 misses %lld \n",values[1]);
   printf("L3 misses %lld \n",values[2]);

   if ( (retval = PAPI_stop(EventSet, values)) != PAPI_OK)
      ERROR_RETURN(retval);



   /* free the resources used by PAPI */
   PAPI_shutdown();

}

And the following code for spawning the thread:

int main()
{
   pthread_t master;
   pthread_t slave1;
   pthread_attr_t attr;
   int rc = 0;

   int retval, number;
   unsigned long pid;
   pid = PAPI_thread_id();
   char errstring[PAPI_MAX_STR_LEN];

   pthread_attr_init(&attr);
   pthread_attr_setscope(&attr, PTHREAD_SCOPE_SYSTEM);

   if((retval = PAPI_library_init(PAPI_VER_CURRENT)) != PAPI_VER_CURRENT )
          ERROR_RETURN(retval); 

   if ((retval = PAPI_thread_init(&pthread_self)) != PAPI_OK)
     ERROR_RETURN(retval);

   rc = pthread_create(&slave1, &attr, Slave, NULL);
   pthread_join(slave1, NULL);
   exit(0);
}

The bad thing is that i get no errors, which indicate that everything is working.