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 #define TIMESPEC_AFTER(a, b) \
  26   (((a).tv_sec == (b).tv_sec) ?                                               \
  27      ((a).tv_nsec > (b).tv_nsec) :                                            \
  28         ((a).tv_sec > (b).tv_sec))
  29 int
  30 main (int argc, char **argv)
  31 {
  32   unsigned long i, k;
  33   struct timespec start, end, runtime;
  34
  35   memset (&runtime, 0, sizeof (runtime));
  36   memset (&start, 0, sizeof (start));
  37   memset (&end, 0, sizeof (end));
  38
  39   clock_getres (CLOCK_PROCESS_CPUTIME_ID, &start);
  40
  41   /* Measure 1000 times the resolution of the clock.  So for a 1ns resolution
  42      clock, we measure 1000 iterations of the function call at a time.
  43      Measurements close to the minimum clock resolution won't make much sense,
  44      but it's better than having nothing at all.  */
  45   unsigned long iters = 1000 * start.tv_nsec;
  46
  47   for (int v = 0; v < NUM_VARIANTS; v++)
  48     {
  49       /* Run for approximately DURATION seconds.  */
  50       clock_gettime (CLOCK_MONOTONIC_RAW, &runtime);
  51       runtime.tv_sec += DURATION;
  52
  53       double d_total_i = 0;
  54       uint64_t total = 0, max = 0, min = 0x7fffffffffffffff;
  55       while (1)
  56         {
  57           for (i = 0; i < NUM_SAMPLES (v); i++)
  58             {
  59               clock_gettime (CLOCK_PROCESS_CPUTIME_ID, &start);
  60               for (k = 0; k < iters; k++)
  61                 BENCH_FUNC (v, i);
  62               clock_gettime (CLOCK_PROCESS_CPUTIME_ID, &end);
  63
  64               uint64_t cur = (end.tv_nsec - start.tv_nsec
  65                               + ((end.tv_sec - start.tv_sec)
  66                                  * (uint64_t) 1000000000));
  67
  68               if (cur > max)
  69                 max = cur;
  70
  71               if (cur < min)
  72                 min = cur;
  73
  74               total += cur;
  75
  76               d_total_i += iters;
  77             }
  78           struct timespec curtime;
  79
  80           memset (&curtime, 0, sizeof (curtime));
  81           clock_gettime (CLOCK_MONOTONIC_RAW, &curtime);
  82           if (TIMESPEC_AFTER (curtime, runtime))
  83             goto done;
  84         }
  85
  86       double d_total_s;
  87       double d_iters;
  88
  89     done:
  90       d_total_s = total * 1e-9;
  91       d_iters = iters;
  92
  93       printf ("%s: ITERS:%g: TOTAL:%gs, MAX:%gns, MIN:%gns, %g iter/s\n",
  94               VARIANT (v),
  95               d_total_i, d_total_s, max / d_iters, min / d_iters,
  96               d_total_i / d_total_s);
  97     }
  98
  99   return 0;
 100 }