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fcyc.c
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224 lines (193 loc) · 4.32 KB
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/* Compute time used by function f */
#include <stdlib.h>
#include <sys/times.h>
#include <stdio.h>
#include "clock.h"
#include "fcyc.h"
#define K 3
#define MAXSAMPLES 20
#define EPSILON 0.01
#define COMPENSATE 0
#define CLEAR_CACHE 0
#define CACHE_BYTES (1<<19)
#define CACHE_BLOCK 32
static long int kbest = K;
static long int compensate = COMPENSATE;
static long int clear_cache = CLEAR_CACHE;
static long int maxsamples = MAXSAMPLES;
static double epsilon = EPSILON;
static long int cache_bytes = CACHE_BYTES;
static long int cache_block = CACHE_BLOCK;
static long int *cache_buf = NULL;
static double *values = NULL;
static long int samplecount = 0;
#define KEEP_VALS 0
#define KEEP_SAMPLES 0
#if KEEP_SAMPLES
static double *samples = NULL;
#endif
/* Start new sampling process */
static void init_sampler()
{
if (values)
free(values);
values = calloc(kbest, sizeof(double));
#if KEEP_SAMPLES
if (samples)
free(samples);
/* Allocate extra for wraparound analysis */
samples = calloc(maxsamples+kbest, sizeof(double));
#endif
samplecount = 0;
}
/* Add new sample. */
static void add_sample(double val)
{
long int pos = 0;
if (samplecount < kbest) {
pos = samplecount;
values[pos] = val;
} else if (val < values[kbest-1]) {
pos = kbest-1;
values[pos] = val;
}
#if KEEP_SAMPLES
samples[samplecount] = val;
#endif
samplecount++;
/* Insertion sort */
while (pos > 0 && values[pos-1] > values[pos]) {
double temp = values[pos-1];
values[pos-1] = values[pos];
values[pos] = temp;
pos--;
}
}
/* Have kbest minimum measurements converged within epsilon? */
static long int has_converged()
{
return
(samplecount >= kbest) &&
((1 + epsilon)*values[0] >= values[kbest-1]);
}
/* Code to clear cache */
static volatile long int sink = 0;
static void clear()
{
long int x = sink;
long int *cptr, *cend;
long int incr = cache_block/sizeof(long int);
if (!cache_buf) {
cache_buf = malloc(cache_bytes);
if (!cache_buf) {
fprintf(stderr, "Fatal error. Malloc returned null when trying to clear cache\n");
exit(1);
}
}
cptr = (long int *) cache_buf;
cend = cptr + cache_bytes/sizeof(long int);
while (cptr < cend) {
x += *cptr;
cptr += incr;
}
sink = x;
}
double fcyc(test_funct f, long int *params)
{
double result;
init_sampler();
if (compensate) {
do {
double cyc;
if (clear_cache)
clear();
start_counter();
f(params);
cyc = get_counter();
if (cyc > 0.0)
add_sample(cyc);
} while (!has_converged() && samplecount < maxsamples);
} else {
do {
double cyc;
if (clear_cache)
clear();
start_counter();
f(params);
cyc = get_counter();
if (cyc > 0.0)
add_sample(cyc);
} while (!has_converged() && samplecount < maxsamples);
}
#ifdef DEBUG
{
long int i;
printf(" %ld smallest values: [", kbest);
for (i = 0; i < kbest; i++)
printf("%.0f%s", values[i], i==kbest-1 ? "]\n" : ", ");
}
#endif
result = values[0];
#if !KEEP_VALS
free(values);
values = NULL;
#endif
return result;
}
/***********************************************************/
/* Set the various parameters used by measurement routines */
/* When set, will run code to clear cache before each measurement
Default = 0
*/
void set_fcyc_clear_cache(long int clear)
{
clear_cache = clear;
}
/* Set size of cache to use when clearing cache
Default = 1<<19 (512KB)
*/
void set_fcyc_cache_sizee(long int bytes)
{
if (bytes != cache_bytes) {
cache_bytes = bytes;
if (cache_buf) {
free(cache_buf);
cache_buf = NULL;
}
}
}
/* Set size of cache block
Default = 32
*/
void set_fcyc_cache_block(long int bytes) {
cache_block = bytes;
}
/* When set, will attempt to compensate for timer interrupt overhead
Default = 0
*/
void set_fcyc_compensate(long int compensate_arg)
{
compensate = compensate_arg;
}
/* Value of K in K-best
Default = 3
*/
void set_fcyc_k(long int k)
{
kbest = k;
}
/* Maximum number of samples attempting to find K-best within some tolerance.
When exceeded, just return best sample found.
Default = 20
*/
void set_fcyc_maxsamples(long int maxsamples_arg)
{
maxsamples = maxsamples_arg;
}
/* Tolerance required for K-best
Default = 0.01
*/
void set_fcyc_epsilon(double epsilon_arg)
{
epsilon = epsilon_arg;
}