107 lines
2.7 KiB
C
107 lines
2.7 KiB
C
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/*
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* ftimer.c - Estimate the time (in seconds) used by a function f
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*
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* Copyright (c) 2002, R. Bryant and D. O'Hallaron, All rights reserved.
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* May not be used, modified, or copied without permission.
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*
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* Function timers that estimate the running time (in seconds) of a function f.
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* ftimer_itimer: version that uses the interval timer
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* ftimer_gettod: version that uses gettimeofday
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*/
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#include <stdio.h>
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#include <sys/time.h>
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#include "ftimer.h"
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/* function prototypes */
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static void init_etime(void);
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static double get_etime(void);
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/*
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* ftimer_itimer - Use the interval timer to estimate the running time
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* of f(argp). Return the average of n runs.
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*/
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double ftimer_itimer(ftimer_test_funct f, void *argp, int n)
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{
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double start, tmeas;
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int i;
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init_etime();
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start = get_etime();
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for (i = 0; i < n; i++)
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f(argp);
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tmeas = get_etime() - start;
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return tmeas / n;
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}
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/*
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* ftimer_gettod - Use gettimeofday to estimate the running time of
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* f(argp). Return the average of n runs.
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*/
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double ftimer_gettod(ftimer_test_funct f, void *argp, int n)
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{
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int i;
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struct timeval stv, etv;
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double diff;
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gettimeofday(&stv, NULL);
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for (i = 0; i < n; i++)
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f(argp);
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gettimeofday(&etv,NULL);
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diff = 1E3*(etv.tv_sec - stv.tv_sec) + 1E-3*(etv.tv_usec-stv.tv_usec);
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diff /= n;
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return (1E-3*diff);
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}
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/*
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* Routines for manipulating the Unix interval timer
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*/
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/* The initial value of the interval timer */
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#define MAX_ETIME 86400
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/* static variables that hold the initial value of the interval timer */
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static struct itimerval first_u; /* user time */
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static struct itimerval first_r; /* real time */
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static struct itimerval first_p; /* prof time*/
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/* init the timer */
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static void init_etime(void)
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{
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first_u.it_interval.tv_sec = 0;
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first_u.it_interval.tv_usec = 0;
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first_u.it_value.tv_sec = MAX_ETIME;
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first_u.it_value.tv_usec = 0;
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setitimer(ITIMER_VIRTUAL, &first_u, NULL);
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first_r.it_interval.tv_sec = 0;
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first_r.it_interval.tv_usec = 0;
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first_r.it_value.tv_sec = MAX_ETIME;
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first_r.it_value.tv_usec = 0;
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setitimer(ITIMER_REAL, &first_r, NULL);
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first_p.it_interval.tv_sec = 0;
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first_p.it_interval.tv_usec = 0;
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first_p.it_value.tv_sec = MAX_ETIME;
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first_p.it_value.tv_usec = 0;
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setitimer(ITIMER_PROF, &first_p, NULL);
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}
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/* return elapsed real seconds since call to init_etime */
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static double get_etime(void) {
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struct itimerval v_curr;
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struct itimerval r_curr;
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struct itimerval p_curr;
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getitimer(ITIMER_VIRTUAL, &v_curr);
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getitimer(ITIMER_REAL,&r_curr);
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getitimer(ITIMER_PROF,&p_curr);
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return (double) ((first_p.it_value.tv_sec - r_curr.it_value.tv_sec) +
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(first_p.it_value.tv_usec - r_curr.it_value.tv_usec)*1e-6);
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}
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