benchtests/bench-skeleton.c

   1 /* Skeleton for benchmark programs.
   2    Copyright (C) 2013-2015 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 <stdbool.h>
  22 #include <stdio.h>
  23 #include <time.h>
  24 #include <inttypes.h>
  25 #include "bench-timing.h"
  26 #include "json-lib.h"
  27
  28 volatile unsigned int dontoptimize = 0;
  29
  30 void
  31 startup (void)
  32 {
  33   /* This loop should cause CPU to switch to maximal freqency.
  34      This makes subsequent measurement more accurate.  We need a side effect
  35      to prevent the loop being deleted by compiler.
  36      This should be enough to cause CPU to speed up and it is simpler than
  37      running loop for constant time. This is used when user does not have root
  38      access to set a constant freqency.  */
  39   for (int k = 0; k < 10000000; k++)
  40     dontoptimize += 23 * dontoptimize + 2;
  41 }
  42
  43 #define TIMESPEC_AFTER(a, b) \
  44   (((a).tv_sec == (b).tv_sec) ?                                               \
  45      ((a).tv_nsec > (b).tv_nsec) :                                            \
  46         ((a).tv_sec > (b).tv_sec))
  47 int
  48 main (int argc, char **argv)
  49 {
  50   unsigned long i, k;
  51   struct timespec runtime;
  52   timing_t start, end;
  53   bool detailed = false;
  54   json_ctx_t json_ctx;
  55
  56   if (argc == 2 && !strcmp (argv[1], "-d"))
  57     detailed = true;
  58
  59   startup();
  60
  61   memset (&runtime, 0, sizeof (runtime));
  62
  63   unsigned long iters, res;
  64
  65 #ifdef BENCH_INIT
  66   BENCH_INIT ();
  67 #endif
  68   TIMING_INIT (res);
  69
  70   iters = 1000 * res;
  71
  72   json_init (&json_ctx, 2, stdout);
  73
  74   /* Begin function.  */
  75   json_attr_object_begin (&json_ctx, FUNCNAME);
  76
  77   for (int v = 0; v < NUM_VARIANTS; v++)
  78     {
  79       /* Run for approximately DURATION seconds.  */
  80       clock_gettime (CLOCK_MONOTONIC_RAW, &runtime);
  81       runtime.tv_sec += DURATION;
  82
  83       double d_total_i = 0;
  84       timing_t total = 0, max = 0, min = 0x7fffffffffffffff;
  85       int64_t c = 0;
  86       while (1)
  87         {
  88           for (i = 0; i < NUM_SAMPLES (v); i++)
  89             {
  90               uint64_t cur;
  91               TIMING_NOW (start);
  92               for (k = 0; k < iters; k++)
  93                 BENCH_FUNC (v, i);
  94               TIMING_NOW (end);
  95
  96               TIMING_DIFF (cur, start, end);
  97
  98               if (cur > max)
  99                 max = cur;
 100
 101               if (cur < min)
 102                 min = cur;
 103
 104               TIMING_ACCUM (total, cur);
 105               /* Accumulate timings for the value.  In the end we will divide
 106                  by the total iterations.  */
 107               RESULT_ACCUM (cur, v, i, c * iters, (c + 1) * iters);
 108
 109               d_total_i += iters;
 110             }
 111           c++;
 112           struct timespec curtime;
 113
 114           memset (&curtime, 0, sizeof (curtime));
 115           clock_gettime (CLOCK_MONOTONIC_RAW, &curtime);
 116           if (TIMESPEC_AFTER (curtime, runtime))
 117             goto done;
 118         }
 119
 120       double d_total_s;
 121       double d_iters;
 122
 123     done:
 124       d_total_s = total;
 125       d_iters = iters;
 126
 127       /* Begin variant.  */
 128       json_attr_object_begin (&json_ctx, VARIANT (v));
 129
 130       json_attr_double (&json_ctx, "duration", d_total_s);
 131       json_attr_double (&json_ctx, "iterations", d_total_i);
 132       json_attr_double (&json_ctx, "max", max / d_iters);
 133       json_attr_double (&json_ctx, "min", min / d_iters);
 134       json_attr_double (&json_ctx, "mean", d_total_s / d_total_i);
 135
 136       if (detailed)
 137         {
 138           json_array_begin (&json_ctx, "timings");
 139
 140           for (int i = 0; i < NUM_SAMPLES (v); i++)
 141             json_element_double (&json_ctx, RESULT (v, i));
 142
 143           json_array_end (&json_ctx);
 144         }
 145
 146       /* End variant.  */
 147       json_attr_object_end (&json_ctx);
 148     }
 149
 150   /* End function.  */
 151   json_attr_object_end (&json_ctx);
 152
 153   return 0;
 154 }