Re: FreeBSD port (30): profiling frequency

[Bruno Haible <bruno at clisp dot org>]

> Thanks, but I don't want to encourage people to insert constants like this.
> On FreeBSD the right thing to do is fetch KERN_CLOCKRATE with sysctl.

Thanks for the tip. But KERN_CLOCKRATE contains four numbers:
100, 10000, 1024, 128. I really need the measuring program in order
to determine which one to use. So here is a again the helper program,
with enough caveats and warnings :-)


2002-09-02  Bruno Haible  <bruno@clisp.org>

	* sysdeps/posix/show-prof-freq.c: New file.
	* sysdeps/posix/Dist: New file.

*** /dev/null	Fri Sep 20 02:00:52 2002
--- glibc-20020910/sysdeps/posix/show-prof-freq.c	Mon Sep  2 00:20:24 2002
***************
*** 0 ****
--- 1,87 ----
+ /* Show the profiler frequency.  Use for porting __profile_frequency().
+    Copyright (C) 2002 Free Software Foundation, Inc.
+    This file is part of the GNU C Library.
+ 
+    The GNU C Library is free software; you can redistribute it and/or
+    modify it under the terms of the GNU Lesser General Public
+    License as published by the Free Software Foundation; either
+    version 2.1 of the License, or (at your option) any later version.
+ 
+    The GNU C Library is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+    Lesser General Public License for more details.
+ 
+    You should have received a copy of the GNU Lesser General Public
+    License along with the GNU C Library; if not, write to the Free
+    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+    02111-1307 USA.  */
+ 
+ /* This program shows the profiler frequency.  Its purpose it to port
+    __profile_frequency().  Note that you should avoid to put immediate
+    constants into the implementation of __profile_frequency() if the
+    information is also available through a kernel API; but this program
+    can at least help you choosing the right API.  */
+ 
+ #include <signal.h>
+ #include <stdio.h>
+ #include <stdlib.h>
+ #include <time.h>
+ #include <unistd.h>
+ #include <sys/time.h>
+ 
+ struct timeval start_time;
+ struct timeval end_time;
+ 
+ int counter;
+ 
+ static void prof_handler ()
+ {
+   counter++;
+ }
+ 
+ static void int_handler ()
+ {
+   /* Take end time.  */
+   gettimeofday (&end_time, NULL);
+ 
+   printf ("\n");
+   printf ("Number of ITIMER_PROF ticks: %d\n", counter);
+   printf ("Frequency of ITIMER_PROF ticks: %g / sec\n",
+ 	  (double) counter
+ 	  / ((end_time.tv_sec + 1e-6 * end_time.tv_usec)
+ 	     - (start_time. tv_sec + 1e-6 * start_time.tv_usec)));
+   printf ("For comparison: CLK_TCK = %d\n", CLK_TCK);
+   exit (0);
+ }
+ 
+ int main ()
+ {
+   struct sigaction act;
+   struct itimerval timer;
+ 
+   printf ("Calibrating...\n");
+ 
+   signal (SIGINT, int_handler);
+   signal (SIGALRM, int_handler);
+ 
+   /* Set up the profiling action.  */
+   act.sa_handler = prof_handler;
+   act.sa_flags = SA_RESTART;
+   sigfillset (&act.sa_mask);
+   sigaction (SIGPROF, &act, NULL);
+ 
+   /* Take start time.  */
+   gettimeofday (&start_time, NULL);
+ 
+   /* Start profiling timer.  */
+   timer.it_value.tv_sec  = 0;
+   timer.it_value.tv_usec = 1;
+   timer.it_interval.tv_sec  = 0;
+   timer.it_interval.tv_usec = 1;
+   setitimer (ITIMER_PROF, &timer, NULL);
+ 
+   alarm (10);
+ 
+   for (;;);
+ }
*** /dev/null	Fri Sep 20 02:00:52 2002
--- glibc-20020910/sysdeps/posix/Dist	Sun Jul  7 01:24:58 2002
***************
*** 0 ****
--- 1 ----
+ show-prof-freq.c