tools/power/cpupower/bench/benchmark.c

   1 /*  cpufreq-bench CPUFreq microbenchmark
   2  *
   3  *  Copyright (C) 2008 Christian Kornacker <ckornacker@suse.de>
   4  *
   5  *  This program is free software; you can redistribute it and/or modify
   6  *  it under the terms of the GNU General Public License as published by
   7  *  the Free Software Foundation; either version 2 of the License, or
   8  *  (at your option) any later version.
   9  *
  10  *  This program 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
  13  *  GNU General Public License for more details.
  14  *
  15  *  You should have received a copy of the GNU General Public License
  16  *  along with this program; if not, write to the Free Software
  17  *  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  18  */
  19
  20 #include <stdio.h>
  21 #include <unistd.h>
  22 #include <math.h>
  23
  24 #include "config.h"
  25 #include "system.h"
  26 #include "benchmark.h"
  27
  28 /* Print out progress if we log into a file */
  29 #define show_progress(total_time, progress_time)        \
  30 if (config->output != stdout) {                         \
  31         fprintf(stdout, "Progress: %02lu %%\r",         \
  32                 (progress_time * 100) / total_time);    \
  33         fflush(stdout);                                 \
  34 }
  35
  36 /**
  37  * compute how many rounds of calculation we should do
  38  * to get the given load time
  39  *
  40  * @param load aimed load time in µs
  41  *
  42  * @retval rounds of calculation
  43  **/
  44
  45 unsigned int calculate_timespace(long load, struct config *config)
  46 {
  47         int i;
  48         long long now, then;
  49         unsigned int estimated = GAUGECOUNT;
  50         unsigned int rounds = 0;
  51         unsigned int timed = 0;
  52
  53         if (config->verbose)
  54                 printf("calibrating load of %lius, please wait...\n", load);
  55
  56         /* get the initial calculation time for a specific number of rounds */
  57         now = get_time();
  58         ROUNDS(estimated);
  59         then = get_time();
  60
  61         timed = (unsigned int)(then - now);
  62
  63         /* approximation of the wanted load time by comparing with the
  64          * initial calculation time */
  65         for (i = 0; i < 4; i++) {
  66                 rounds = (unsigned int)(load * estimated / timed);
  67                 dprintf("calibrating with %u rounds\n", rounds);
  68                 now = get_time();
  69                 ROUNDS(rounds);
  70                 then = get_time();
  71
  72                 timed = (unsigned int)(then - now);
  73                 estimated = rounds;
  74         }
  75         if (config->verbose)
  76                 printf("calibration done\n");
  77
  78         return estimated;
  79 }
  80
  81 /**
  82  * benchmark
  83  * generates a specific sleep an load time with the performance
  84  * governor and compares the used time for same calculations done
  85  * with the configured powersave governor
  86  *
  87  * @param config config values for the benchmark
  88  *
  89  **/
  90
  91 void start_benchmark(struct config *config)
  92 {
  93         unsigned int _round, cycle;
  94         long long now, then;
  95         long sleep_time = 0, load_time = 0;
  96         long performance_time = 0, powersave_time = 0;
  97         unsigned int calculations;
  98         unsigned long total_time = 0, progress_time = 0;
  99
 100         sleep_time = config->sleep;
 101         load_time = config->load;
 102
 103         /* For the progress bar */
 104         for (_round = 1; _round <= config->rounds; _round++)
 105                 total_time += _round * (config->sleep + config->load);
 106         total_time *= 2; /* powersave and performance cycles */
 107
 108         for (_round = 0; _round < config->rounds; _round++) {
 109                 performance_time = 0LL;
 110                 powersave_time = 0LL;
 111
 112                 show_progress(total_time, progress_time);
 113
 114                 /* set the cpufreq governor to "performance" which disables
 115                  * P-State switching. */
 116                 if (set_cpufreq_governor("performance", config->cpu) != 0)
 117                         return;
 118
 119                 /* calibrate the calculation time. the resulting calculation
 120                  * _rounds should produce a load which matches the configured
 121                  * load time */
 122                 calculations = calculate_timespace(load_time, config);
 123
 124                 if (config->verbose)
 125                         printf("_round %i: doing %u cycles with %u calculations"
 126                                " for %lius\n", _round + 1, config->cycles,
 127                                calculations, load_time);
 128
 129                 fprintf(config->output, "%u %li %li ",
 130                         _round, load_time, sleep_time);
 131
 132                 if (config->verbose)
 133                         printf("average: %lius, rps:%li\n",
 134                                 load_time / calculations,
 135                                 1000000 * calculations / load_time);
 136
 137                 /* do some sleep/load cycles with the performance governor */
 138                 for (cycle = 0; cycle < config->cycles; cycle++) {
 139                         now = get_time();
 140                         usleep(sleep_time);
 141                         ROUNDS(calculations);
 142                         then = get_time();
 143                         performance_time += then - now - sleep_time;
 144                         if (config->verbose)
 145                                 printf("performance cycle took %lius, "
 146                                         "sleep: %lius, "
 147                                         "load: %lius, rounds: %u\n",
 148                                         (long)(then - now), sleep_time,
 149                                         load_time, calculations);
 150                 }
 151                 fprintf(config->output, "%li ",
 152                         performance_time / config->cycles);
 153
 154                 progress_time += sleep_time + load_time;
 155                 show_progress(total_time, progress_time);
 156
 157                 /* set the powersave governor which activates P-State switching
 158                  * again */
 159                 if (set_cpufreq_governor(config->governor, config->cpu) != 0)
 160                         return;
 161
 162                 /* again, do some sleep/load cycles with the
 163                  * powersave governor */
 164                 for (cycle = 0; cycle < config->cycles; cycle++) {
 165                         now = get_time();
 166                         usleep(sleep_time);
 167                         ROUNDS(calculations);
 168                         then = get_time();
 169                         powersave_time += then - now - sleep_time;
 170                         if (config->verbose)
 171                                 printf("powersave cycle took %lius, "
 172                                         "sleep: %lius, "
 173                                         "load: %lius, rounds: %u\n",
 174                                         (long)(then - now), sleep_time,
 175                                         load_time, calculations);
 176                 }
 177
 178                 progress_time += sleep_time + load_time;
 179
 180                 /* compare the average sleep/load cycles  */
 181                 fprintf(config->output, "%li ",
 182                         powersave_time / config->cycles);
 183                 fprintf(config->output, "%.3f\n",
 184                         performance_time * 100.0 / powersave_time);
 185                 fflush(config->output);
 186
 187                 if (config->verbose)
 188                         printf("performance is at %.2f%%\n",
 189                                 performance_time * 100.0 / powersave_time);
 190
 191                 sleep_time += config->sleep_step;
 192                 load_time += config->load_step;
 193         }
 194 }