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299 wiersze
6.3 KiB
299 wiersze
6.3 KiB
/* Compute time used by a function f that takes two integer args */
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#include <stdlib.h>
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#include <sys/times.h>
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#include <stdio.h>
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#include "clock.h"
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#include "fcyc2.h"
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static double *values = NULL;
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int samplecount = 0;
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#define KEEP_VALS 1
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#define KEEP_SAMPLES 1
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#if KEEP_SAMPLES
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double *samples = NULL;
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#endif
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/* Start new sampling process */
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static void init_sampler(int k, int maxsamples)
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{
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if (values)
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free(values);
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values = calloc(k, sizeof(double));
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#if KEEP_SAMPLES
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if (samples)
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free(samples);
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/* Allocate extra for wraparound analysis */
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samples = calloc(maxsamples+k, sizeof(double));
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#endif
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samplecount = 0;
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}
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/* Add new sample. */
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void add_sample(double val, int k)
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{
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int pos = 0;
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if (samplecount < k) {
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pos = samplecount;
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values[pos] = val;
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} else if (val < values[k-1]) {
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pos = k-1;
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values[pos] = val;
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}
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#if KEEP_SAMPLES
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samples[samplecount] = val;
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#endif
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samplecount++;
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/* Insertion sort */
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while (pos > 0 && values[pos-1] > values[pos]) {
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double temp = values[pos-1];
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values[pos-1] = values[pos];
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values[pos] = temp;
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pos--;
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}
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}
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/* Get current minimum */
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double get_min()
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{
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return values[0];
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}
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/* What is relative error for kth smallest sample */
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double err(int k)
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{
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if (samplecount < k)
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return 1000.0;
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return (values[k-1] - values[0])/values[0];
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}
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/* Have k minimum measurements converged within epsilon? */
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int has_converged(int k_arg, double epsilon_arg, int maxsamples)
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{
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if ((samplecount >= k_arg) &&
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((1 + epsilon_arg)*values[0] >= values[k_arg-1]))
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return samplecount;
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if ((samplecount >= maxsamples))
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return -1;
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return 0;
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}
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/* Code to clear cache */
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/* Pentium III has 512K L2 cache, which is 128K ints */
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#define ASIZE (1 << 17)
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/* Cache block size is 32 bytes */
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#define STRIDE 8
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static int stuff[ASIZE];
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static int sink;
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static void clear()
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{
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int x = sink;
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int i;
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for (i = 0; i < ASIZE; i += STRIDE)
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x += stuff[i];
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sink = x;
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}
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double fcyc2_full(test_funct f, int param1, int param2, int clear_cache,
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int k, double epsilon, int maxsamples, int compensate)
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{
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double result;
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init_sampler(k, maxsamples);
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if (compensate) {
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do {
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double cyc;
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if (clear_cache)
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clear();
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f(param1, param2); /* warm cache */
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start_comp_counter();
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f(param1, param2);
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cyc = get_comp_counter();
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add_sample(cyc, k);
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} while (!has_converged(k, epsilon, maxsamples) && samplecount < maxsamples);
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} else {
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do {
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double cyc;
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if (clear_cache)
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clear();
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f(param1, param2); /* warm cache */
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start_counter();
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f(param1, param2);
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cyc = get_counter();
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add_sample(cyc, k);
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} while (!has_converged(k, epsilon, maxsamples) && samplecount < maxsamples);
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}
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#ifdef DEBUG
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{
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int i;
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printf(" %d smallest values: [", k);
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for (i = 0; i < k; i++)
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printf("%.0f%s", values[i], i==k-1 ? "]\n" : ", ");
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}
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#endif
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result = values[0];
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#if !KEEP_VALS
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free(values);
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values = NULL;
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#endif
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return result;
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}
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double fcyc2(test_funct f, int param1, int param2, int clear_cache)
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{
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return fcyc2_full(f, param1, param2, clear_cache, 3, 0.01, 500, 0);
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}
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/******************* Version that uses gettimeofday *************/
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static double Mhz = 0.0;
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#include <sys/time.h>
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static struct timeval tstart;
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/* Record current time */
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void start_counter_tod()
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{
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if (Mhz == 0)
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Mhz = mhz_full(0, 10);
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gettimeofday(&tstart, NULL);
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}
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/* Get number of seconds since last call to start_timer */
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double get_counter_tod()
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{
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struct timeval tfinish;
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long sec, usec;
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gettimeofday(&tfinish, NULL);
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sec = tfinish.tv_sec - tstart.tv_sec;
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usec = tfinish.tv_usec - tstart.tv_usec;
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return (1e6 * sec + usec)*Mhz;
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}
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/** Special counters that compensate for timer interrupt overhead */
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static double cyc_per_tick = 0.0;
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#define NEVENT 100
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#define THRESHOLD 1000
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#define RECORDTHRESH 3000
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/* Attempt to see how much time is used by timer interrupt */
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static void callibrate(int verbose)
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{
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double oldt;
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struct tms t;
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clock_t oldc;
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int e = 0;
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times(&t);
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oldc = t.tms_utime;
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start_counter_tod();
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oldt = get_counter_tod();
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while (e <NEVENT) {
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double newt = get_counter_tod();
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if (newt-oldt >= THRESHOLD) {
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clock_t newc;
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times(&t);
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newc = t.tms_utime;
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if (newc > oldc) {
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double cpt = (newt-oldt)/(newc-oldc);
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if ((cyc_per_tick == 0.0 || cyc_per_tick > cpt) && cpt > RECORDTHRESH)
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cyc_per_tick = cpt;
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/*
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if (verbose)
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printf("Saw event lasting %.0f cycles and %d ticks. Ratio = %f\n",
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newt-oldt, (int) (newc-oldc), cpt);
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*/
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e++;
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oldc = newc;
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}
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oldt = newt;
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}
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}
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if (verbose)
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printf("Setting cyc_per_tick to %f\n", cyc_per_tick);
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}
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static clock_t start_tick = 0;
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void start_comp_counter_tod() {
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struct tms t;
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if (cyc_per_tick == 0.0)
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callibrate(0);
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times(&t);
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start_tick = t.tms_utime;
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start_counter_tod();
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}
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double get_comp_counter_tod() {
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double time = get_counter_tod();
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double ctime;
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struct tms t;
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clock_t ticks;
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times(&t);
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ticks = t.tms_utime - start_tick;
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ctime = time - ticks*cyc_per_tick;
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/*
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printf("Measured %.0f cycles. Ticks = %d. Corrected %.0f cycles\n",
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time, (int) ticks, ctime);
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*/
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return ctime;
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}
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double fcyc2_full_tod(test_funct f, int param1, int param2, int clear_cache,
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int k, double epsilon, int maxsamples, int compensate)
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{
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double result;
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init_sampler(k, maxsamples);
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if (compensate) {
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do {
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double cyc;
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if (clear_cache)
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clear();
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start_comp_counter_tod();
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f(param1, param2);
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cyc = get_comp_counter_tod();
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add_sample(cyc, k);
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} while (!has_converged(k, epsilon, maxsamples) && samplecount < maxsamples);
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} else {
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do {
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double cyc;
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if (clear_cache)
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clear();
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start_counter_tod();
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f(param1, param2);
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cyc = get_counter_tod();
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add_sample(cyc, k);
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} while (!has_converged(k, epsilon, maxsamples) && samplecount < maxsamples);
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}
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#ifdef DEBUG
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{
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int i;
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printf(" %d smallest values: [", k);
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for (i = 0; i < k; i++)
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printf("%.0f%s", values[i], i==k-1 ? "]\n" : ", ");
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}
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#endif
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result = values[0];
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#if !KEEP_VALS
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free(values);
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values = NULL;
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#endif
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return result;
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}
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double fcyc2_tod(test_funct f, int param1, int param2, int clear_cache)
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{
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return fcyc2_full_tod(f, param1, param2, clear_cache, 3, 0.01, 20, 0);
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}
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