static void
print_results(double cpu_mhz,
unsigned long * timestamps,
size_t iteration_count,
unsigned long test_duration_cycles,
uint64_t limit_ns)
{
double ns_per_cycle = 1000. / cpu_mhz;
size_t min_index = gsl_stats_ulong_min_index(timestamps, 1,
iteration_count);
size_t max_index = gsl_stats_ulong_max_index(timestamps, 1,
iteration_count);
double mean = gsl_stats_ulong_mean(timestamps, 1, iteration_count);
double sd = gsl_stats_ulong_sd(timestamps, 1, iteration_count);
fprintf(stdout, "Samples count: %'zu\n"
"Sampling duration: %'.0lf ms\n"
"Detected frequency: %.0lf Mhz\n"
"\n"
"Min: %'.0lf ns @%zu\n"
"Mean: %'.0lf ns\n"
"Max: %'.0lf ns @%zu\n"
"\n"
"Std: %'.0lf ns\n",
iteration_count,
test_duration_cycles * ns_per_cycle / (1000. * 1000.),
cpu_mhz,
ns_per_cycle * timestamps[min_index], min_index,
ns_per_cycle * mean,
ns_per_cycle * timestamps[max_index], max_index,
ns_per_cycle * sd);
if (limit_ns)
print_results_above(limit_ns,
ns_per_cycle,
timestamps,
iteration_count,
timestamps[max_index]);
}
uint64_t calc_rdtsc_overhead() {
uint32_t TRIALS = 1000000;
uint64_t* times = (uint64_t*) calloc(TRIALS,sizeof(uint64_t));
uint64_t start=0, end=0;
for(uint32_t i = 0; i < TRIALS; i++){
start = rdtsc64();
end = rdtsc64();
times[i] = (end -start)>0?(end - start):0;
}
gsl_sort_ulong((unsigned long*)times,1,TRIALS);
uint64_t median = gsl_stats_ulong_median_from_sorted_data ((unsigned long*)times,1,TRIALS);
#ifdef DEBUG
double mean = gsl_stats_ulong_mean(times, 1, TRIALS);
double sd = gsl_stats_ulong_sd(times, 1, TRIALS);
uint64_t max = times[TRIALS-1];
uint64_t min = times[0];
#endif
free(times);
#ifdef DEBUG
printf("| Median: %lu | Mean: %6.3f | Std Deviation: %6.3f | Min: %lu | Max: %lu |\n",median,mean,sd,min,max);
#endif
return median;
}
