benchtests/bench-skeleton.c

   1 /* Skeleton for benchmark programs.
   2    Copyright (C) 2013 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 #include <string.h>
  20 #include <stdint.h>
  21 #include <stdio.h>
  22 #include <time.h>
  23 #include <inttypes.h>
  24
  25 int
  26 main (int argc, char **argv)
  27 {
  28   unsigned long i, j, k;
  29   uint64_t total = 0, max = 0, min = 0x7fffffffffffffff;
  30   struct timespec start, end;
  31
  32   memset (&start, 0, sizeof (start));
  33   memset (&end, 0, sizeof (end));
  34
  35   clock_getres (CLOCK_PROCESS_CPUTIME_ID, &start);
  36
  37   /* Measure 1000 times the resolution of the clock.  So for a 1ns resolution
  38      clock, we measure 1000 iterations of the function call at a time.
  39      Measurements close to the minimum clock resolution won't make much sense,
  40      but it's better than having nothing at all.  */
  41   unsigned long iters = 1000 * start.tv_nsec;
  42   unsigned long total_iters = ITER / iters;
  43
  44   for (i = 0; i < NUM_SAMPLES; i++)
  45     {
  46       for (j = 0; j < total_iters; j ++)
  47         {
  48           clock_gettime (CLOCK_PROCESS_CPUTIME_ID, &start);
  49           for (k = 0; k < iters; k++)
  50             BENCH_FUNC(i);
  51           clock_gettime (CLOCK_PROCESS_CPUTIME_ID, &end);
  52
  53           uint64_t cur = (end.tv_nsec - start.tv_nsec
  54                          + ((end.tv_sec - start.tv_sec)
  55                             * (uint64_t) 1000000000));
  56
  57           if (cur > max)
  58             max = cur;
  59
  60           if (cur < min)
  61             min = cur;
  62
  63           total += cur;
  64         }
  65     }
  66
  67   double d_total_s = total * 1e-9;
  68   double d_iters = iters;
  69   double d_total_i = (double)ITER * NUM_SAMPLES;
  70   printf (FUNCNAME ": ITERS:%g: TOTAL:%gs, MAX:%gns, MIN:%gns, %g iter/s\n",
  71           d_total_i, d_total_s, max / d_iters, min / d_iters,
  72           d_total_i / d_total_s);
  73
  74   return 0;
  75 }