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main.c
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#include <stdio.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <stdint.h>
#include <time.h>
#include <omp.h>
#include <errno.h>
#include "kernels.h"
#define CLOCK_TO_USE CLOCK_MONOTONIC_RAW
//#define CLOCK_TO_USE CLOCK_MONOTONIC_COARSE
#define timespec_to_ns(ts) ((ts)->tv_nsec + (uint64_t)(ts)->tv_sec * 1000000000)
#define MAX_FNAME 64
#define FNAME_PREFIX "samples_from_thread_"
#define FNAME_POSTFIX ".csv"
uint64_t number_of_omp_threads;
uint64_t *kernel_execution_samples;
uint64_t *instrumentation_overhead_samples;
uint64_t get_time_in_ns(struct timespec *tspec)
{
clock_gettime(CLOCK_TO_USE, tspec);
return timespec_to_ns(tspec);
}
uint64_t initialize(uint64_t number_of_samples)
{
uint64_t i, j, number_of_samples_per_thread;
number_of_omp_threads = omp_get_max_threads();
number_of_samples_per_thread = number_of_samples / number_of_omp_threads;
kernel_execution_samples = (uint64_t *)malloc(sizeof(uint64_t) * number_of_samples);
instrumentation_overhead_samples = (uint64_t *)malloc( sizeof(uint64_t) * number_of_samples);
if(!instrumentation_overhead_samples || ! kernel_execution_samples)
{
printf("failed to allocate required memory to hold all the samples");
exit(-ENOMEM);
}
#ifndef DONT_TOUCH_BUFFERS_BEFORE_INIT
for(i=0; i<number_of_samples ; ++i)
{
instrumentation_overhead_samples[i] = 0;
kernel_execution_samples[i] = 0;
}
#endif
return number_of_samples_per_thread;
}
int main(int argc, char *argv[])
{
uint64_t sample_num = 0, per_thread_sample_num = 0, i;
uint64_t kernel_max=0, kernel_min=0, instrumentation_min=0 , instrumentation_max=0;
struct timespec clock_resolution, instrumentation_ts;
char *instrumentation_samples_fname = "samples_instrumentation_samples.csv";
double mean_kernel = 0.0, variance_kernel = 0.0,
mean_instrumentation = 0.0, variance_instrumentation = 0.0;
FILE *inst_fp;
dtype a,b,c,r;
if(argc != 2)
{
printf("usage: %s <number of samples>\n", argv[0]);
return -EINVAL;
}
errno = 0;
sample_num = strtol(argv[1], NULL, 0);
if(errno || !sample_num)
{
printf("Invalid number of samples\n");
return -EINVAL;
}
per_thread_sample_num = initialize(sample_num);
printf("OS noise characterisation\n");
printf("number of threads: %lu\n", number_of_omp_threads);
printf("kernel size: %d\n", KERN_SIZE);
printf("numer of samples: %lu\n", sample_num);
printf("number of samples per thread: %lu\n", per_thread_sample_num);
clock_getres(CLOCK_TO_USE, &clock_resolution);
printf("clock resolution: %lu\n", timespec_to_ns(&clock_resolution));
for(i = 0; i < sample_num; ++i)
{
instrumentation_overhead_samples[i] = get_time_in_ns(&instrumentation_ts);
}
#pragma omp parallel num_threads(number_of_omp_threads)
{
uint64_t j, start, stop;
uint64_t *sample_slice;
char result_fname[MAX_FNAME];
dtype r, a, b;
struct timespec slice_ts;
int id = omp_get_thread_num();
sample_slice = kernel_execution_samples + id * per_thread_sample_num;
#pragma omp barrier
for(j = 0; j < per_thread_sample_num; ++j)
{
r = 0.0;
a = 1.0002;
b = 1.9999;
start = get_time_in_ns(&slice_ts);
#ifdef OUTER_LOOP_THREAD_SYNC
#pragma omp barrier
#endif
kernel_ab(r, a, b);
stop = get_time_in_ns(&slice_ts);
sample_slice[j] = stop - start;
}
#pragma omp barrier
sprintf(result_fname, "%s%d%s", FNAME_PREFIX, id, FNAME_POSTFIX);
#ifndef SKIP_RAW_DATA
FILE *fp = fopen(result_fname, "w");
for(j = 0; j < per_thread_sample_num; ++j)
{
fprintf(fp, "%lu\n", sample_slice[j]);
}
fclose(fp);
#endif
}
#ifndef SKIP_RAW_DATA
inst_fp = fopen(instrumentation_samples_fname, "w");
#endif
for(i = 0; i < sample_num-1; ++i)
{
mean_kernel += ((double)kernel_execution_samples[i]) / ((double) sample_num);
instrumentation_overhead_samples[i] = instrumentation_overhead_samples[i+1] - instrumentation_overhead_samples[i];
mean_instrumentation += ((double)instrumentation_overhead_samples[i]) / ((double)sample_num);
#ifndef SKIP_RAW_DATA
fprintf(inst_fp, "%lu\n", instrumentation_overhead_samples[i]);
#endif
}
mean_kernel += ((double)kernel_execution_samples[sample_num-1]) / ((double) sample_num);
instrumentation_overhead_samples[sample_num-1] = instrumentation_overhead_samples[0];
mean_instrumentation += ((double)instrumentation_overhead_samples[sample_num-1]) / ((double)sample_num);
#ifndef SKIP_RAW_DATA
fprintf(inst_fp, "%lu\n", instrumentation_overhead_samples[sample_num-1]);
#endif
kernel_max = kernel_execution_samples[0];
kernel_min = kernel_execution_samples[0];
instrumentation_max = instrumentation_overhead_samples[0];
instrumentation_min = instrumentation_overhead_samples[0];
for(i = 0; i < sample_num; ++i)
{
variance_kernel += (((double)kernel_execution_samples[i] - mean_kernel) *
((double)kernel_execution_samples[i] - mean_kernel))
/(double)sample_num;
variance_instrumentation += (((double)instrumentation_overhead_samples[i] - mean_instrumentation) *
((double)instrumentation_overhead_samples[i] - mean_instrumentation))
/(double)sample_num;
kernel_max = kernel_execution_samples[i] > kernel_max ? kernel_execution_samples[i] : kernel_max ;
kernel_min = kernel_execution_samples[i] < kernel_min ? kernel_execution_samples[i] : kernel_min ;
instrumentation_max = instrumentation_overhead_samples[i] > instrumentation_max ? instrumentation_overhead_samples[i] : instrumentation_max;
instrumentation_min = instrumentation_overhead_samples[i] < instrumentation_min ? instrumentation_overhead_samples[i] : instrumentation_min;
}
#ifndef SKIP_RAW_DATA
fclose(inst_fp);
#endif
printf("\n\n ==== RESULTS ====\n\n");
printf("noise mean: %lf\n", mean_kernel);
printf("noise variance: %lf\n", variance_kernel);
printf("noise max: %lu\n", kernel_max);
printf("noise min: %lu\n", kernel_min);
printf("instrumentation overhead mean: %lf\n", mean_instrumentation);
printf("instrumentation overhead variance: %lf\n", variance_instrumentation);
printf("instrumentation max: %lu\n", instrumentation_max);
printf("instrumentation min: %lu\n", instrumentation_min);
return 0;
}