Alex Vinokur [EMAIL PROTECTED] wrote in message news:[EMAIL PROTECTED]
clock : Calculates the best available approximation of the cumulative amount of
time used by your program since it started. (From man clock).
Does clock() calculate user-used-time + system-used-time?
Yes, it is.
===
Windows 2000 Professional
CYGWIN_NT-5.0 1.5.4(0.94/3/2)
gcc version 3.3.1 (cygming special)
===
= C code : File t.c : BEGIN =
#include stdio.h
#include stdlib.h
#include time.h
#include sys/resource.h
#include assert.h
int main(int argc, char** argv)
{
clock_t start_clock,
end_clock;
struct rusage start_rusage,
end_rusage;
clock_t diff_clock;
double diff_rusage_user,
diff_rusage_system;
int i;
assert (argc 1);
fprintf (stderr, - Start -\n);
start_clock = clock();
getrusage(RUSAGE_SELF, start_rusage);
for (i = 0; i atoi (argv[1]); i++) printf (ABC\n);
getrusage(RUSAGE_SELF, end_rusage);
end_clock = clock();
assert (!(start_clock == (clock_t)(-1)));
assert (!(end_clock == (clock_t)(-1)));
diff_clock = end_clock - start_clock;
fprintf (stderr, \n);
fprintf (stderr, clock : start = %lu ticks, end = %lu ticks\n,
start_clock, end_clock);
fprintf (stderr, clock : elapsed time = %.2f sec\n,
(double)(diff_clock)/CLOCKS_PER_SEC);
diff_rusage_user =
(end_rusage.ru_utime.tv_sec - start_rusage.ru_utime.tv_sec)
+
(end_rusage.ru_utime.tv_usec - start_rusage.ru_utime.tv_usec)/ 1.0e6;
fprintf (stderr, \n);
fprintf (stderr, rusage user : start = (%ld sec, %ld msec), end = (%ld sec, %ld
msec)\n,
start_rusage.ru_utime.tv_sec,
start_rusage.ru_utime.tv_usec,
end_rusage.ru_utime.tv_sec,
end_rusage.ru_utime.tv_usec
);
fprintf (stderr, rusage user : elapsed time = %.2f sec\n, diff_rusage_user);
diff_rusage_system =
(end_rusage.ru_stime.tv_sec - start_rusage.ru_stime.tv_sec)
+
(end_rusage.ru_stime.tv_usec - start_rusage.ru_stime.tv_usec)/ 1.0e6;
fprintf (stderr, \n);
fprintf (stderr, rusage system : start = (%ld sec, %ld msec), end = (%ld sec, %ld
msec)\n,
start_rusage.ru_stime.tv_sec,
start_rusage.ru_stime.tv_usec,
end_rusage.ru_stime.tv_sec,
end_rusage.ru_stime.tv_usec
);
fprintf (stderr, rusage system : elapsed time = %.2f sec\n, diff_rusage_system);
fprintf (stderr, \n- Finish \n\n);
return 0;
}
= C code : File t.c : END ===
= Compilation Run : BEGIN ===
$ gcc t.c
$ a 1
- Start -
ABC
ABC
ABC
[---omitted---]
ABC
ABC
ABC
clock : start = 10 ticks, end = 900 ticks
clock : elapsed time = 0.89 sec
rusage user : start = (0 sec, 1 msec), end = (0 sec, 54 msec)
rusage user : elapsed time = 0.53 sec
rusage system : start = (0 sec, 0 msec), end = (0 sec, 36 msec)
rusage system : elapsed time = 0.36 sec
- Finish
= Compilation Run : END =
We can see that
clock elapsed time (0.89) == rusage user elapsed time (0.53) + rusage system elapsed
time (0.36)
=
Alex Vinokur
mailto:[EMAIL PROTECTED]
http://mathforum.org/library/view/10978.html
news://news.gmane.org/gmane.comp.lang.c++.perfometer
=
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