benchtests/bench-arc4random.c

   1 /* arc4random benchmarks.
   2    Copyright (C) 2022-2023 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    <https://www.gnu.org/licenses/>.  */
  18
  19 #include "bench-timing.h"
  20 #include "bench-util.h"
  21 #include "json-lib.h"
  22 #include <array_length.h>
  23 #include <intprops.h>
  24 #include <signal.h>
  25 #include <stdbool.h>
  26 #include <stdio.h>
  27 #include <stdlib.h>
  28 #include <support/support.h>
  29 #include <support/timespec.h>
  30 #include <support/xthread.h>
  31
  32 static volatile sig_atomic_t timer_finished;
  33
  34 static void timer_callback (int unused)
  35 {
  36   timer_finished = 1;
  37 }
  38
  39 static timer_t timer;
  40
  41 /* Run for approximately DURATION seconds, and it does not matter who
  42    receive the signal (so not need to mask it on main thread).  */
  43 static void
  44 timer_start (void)
  45 {
  46   timer_finished = 0;
  47   timer = support_create_timer (DURATION, 0, false, timer_callback);
  48 }
  49 static void
  50 timer_stop (void)
  51 {
  52   support_delete_timer (timer);
  53 }
  54
  55 static const uint32_t sizes[] = { 0, 16, 32, 48, 64, 80, 96, 112, 128 };
  56
  57 static double
  58 bench_throughput (void)
  59 {
  60   uint64_t n = 0;
  61
  62   struct timespec start, end;
  63   clock_gettime (CLOCK_MONOTONIC, &start);
  64   while (1)
  65     {
  66       DO_NOT_OPTIMIZE_OUT (arc4random ());
  67       n++;
  68
  69       if (timer_finished == 1)
  70         break;
  71     }
  72   clock_gettime (CLOCK_MONOTONIC, &end);
  73   struct timespec diff = timespec_sub (end, start);
  74
  75   double total = (double) n * sizeof (uint32_t);
  76   double duration = (double) diff.tv_sec
  77     + (double) diff.tv_nsec / TIMESPEC_HZ;
  78
  79   return total / duration;
  80 }
  81
  82 static double
  83 bench_latency (void)
  84 {
  85   timing_t start, stop, cur;
  86   const size_t iters = 1024;
  87
  88   TIMING_NOW (start);
  89   for (size_t i = 0; i < iters; i++)
  90     DO_NOT_OPTIMIZE_OUT (arc4random ());
  91   TIMING_NOW (stop);
  92
  93   TIMING_DIFF (cur, start, stop);
  94
  95   return (double) (cur) / (double) iters;
  96 }
  97
  98 static double
  99 bench_buf_throughput (size_t len)
 100 {
 101   uint8_t buf[len];
 102   uint64_t n = 0;
 103
 104   struct timespec start, end;
 105   clock_gettime (CLOCK_MONOTONIC, &start);
 106   while (1)
 107     {
 108       arc4random_buf (buf, len);
 109       n++;
 110
 111       if (timer_finished == 1)
 112         break;
 113     }
 114   clock_gettime (CLOCK_MONOTONIC, &end);
 115   struct timespec diff = timespec_sub (end, start);
 116
 117   double total = (double) n * len;
 118   double duration = (double) diff.tv_sec
 119     + (double) diff.tv_nsec / TIMESPEC_HZ;
 120
 121   return total / duration;
 122 }
 123
 124 static double
 125 bench_buf_latency (size_t len)
 126 {
 127   timing_t start, stop, cur;
 128   const size_t iters = 1024;
 129
 130   uint8_t buf[len];
 131
 132   TIMING_NOW (start);
 133   for (size_t i = 0; i < iters; i++)
 134     arc4random_buf (buf, len);
 135   TIMING_NOW (stop);
 136
 137   TIMING_DIFF (cur, start, stop);
 138
 139   return (double) (cur) / (double) iters;
 140 }
 141
 142 static void
 143 bench_singlethread (json_ctx_t *json_ctx)
 144 {
 145   json_element_object_begin (json_ctx);
 146
 147   json_array_begin (json_ctx, "throughput");
 148   for (int i = 0; i < array_length (sizes); i++)
 149     {
 150       timer_start ();
 151       double r = sizes[i] == 0
 152         ? bench_throughput () : bench_buf_throughput (sizes[i]);
 153       timer_stop ();
 154
 155       json_element_double (json_ctx, r);
 156     }
 157   json_array_end (json_ctx);
 158
 159   json_array_begin (json_ctx, "latency");
 160   for (int i = 0; i < array_length (sizes); i++)
 161     {
 162       timer_start ();
 163       double r = sizes[i] == 0
 164         ? bench_latency () : bench_buf_latency (sizes[i]);
 165       timer_stop ();
 166
 167       json_element_double (json_ctx, r);
 168     }
 169   json_array_end (json_ctx);
 170
 171   json_element_object_end (json_ctx);
 172 }
 173
 174 static void
 175 run_bench (json_ctx_t *json_ctx, const char *name,
 176            char *const*fnames, size_t fnameslen,
 177            void (*bench) (json_ctx_t *ctx))
 178 {
 179   json_attr_object_begin (json_ctx, name);
 180   json_array_begin (json_ctx, "functions");
 181   for (int i = 0; i < fnameslen; i++)
 182     json_element_string (json_ctx, fnames[i]);
 183   json_array_end (json_ctx);
 184
 185   json_array_begin (json_ctx, "results");
 186   bench (json_ctx);
 187   json_array_end (json_ctx);
 188   json_attr_object_end (json_ctx);
 189 }
 190
 191 static int
 192 do_test (void)
 193 {
 194   char *fnames[array_length (sizes)];
 195   for (int i = 0; i < array_length (sizes); i++)
 196     if (sizes[i] == 0)
 197       fnames[i] = xasprintf ("arc4random");
 198     else
 199       fnames[i] = xasprintf ("arc4random_buf(%u)", sizes[i]);
 200
 201   json_ctx_t json_ctx;
 202   json_init (&json_ctx, 0, stdout);
 203
 204   json_document_begin (&json_ctx);
 205   json_attr_string (&json_ctx, "timing_type", TIMING_TYPE);
 206
 207   run_bench (&json_ctx, "single-thread", fnames, array_length (fnames),
 208              bench_singlethread);
 209
 210   json_document_end (&json_ctx);
 211
 212   for (int i = 0; i < array_length (sizes); i++)
 213     free (fnames[i]);
 214
 215   return 0;
 216 }
 217
 218 #include <support/test-driver.c>