// SPDX-License-Identifier: GPL-2.0-or-later
/*  cpufreq-bench CPUFreq microbenchmark
 *
 *  Copyright (C) 2008 Christian Kornacker <ckornacker@suse.de>
 */

#include <stdio.h>
#include <unistd.h>
#include <math.h>

#include "config.h"
#include "system.h"
#include "benchmark.h"

/* Print out progress if we log into a file */
#define show_progress(total_time, progress_time)        \
if (config->output != stdout) {                         \
        fprintf(stdout, "Progress: %02lu %%\r",         \
                (progress_time * 100) / total_time);    \
        fflush(stdout);                                 \
}

/**
 * compute how many rounds of calculation we should do
 * to get the given load time
 *
 * @param load aimed load time in µs
 *
 * @retval rounds of calculation
 **/

unsigned int calculate_timespace(long load, struct config *config)
{
        int i;
        long long now, then;
        unsigned int estimated = GAUGECOUNT;
        unsigned int rounds = 0;
        unsigned int timed = 0;

        if (config->verbose)
                printf("calibrating load of %lius, please wait...\n", load);

        /* get the initial calculation time for a specific number of rounds */
        now = get_time();
        ROUNDS(estimated);
        then = get_time();

        timed = (unsigned int)(then - now);

        /* approximation of the wanted load time by comparing with the
         * initial calculation time */
        for (i = 0; i < 4; i++) {
                rounds = (unsigned int)(load * estimated / timed);
                dprintf("calibrating with %u rounds\n", rounds);
                now = get_time();
                ROUNDS(rounds);
                then = get_time();

                timed = (unsigned int)(then - now);
                estimated = rounds;
        }
        if (config->verbose)
                printf("calibration done\n");

        return estimated;
}

/**
 * benchmark
 * generates a specific sleep an load time with the performance
 * governor and compares the used time for same calculations done
 * with the configured powersave governor
 *
 * @param config config values for the benchmark
 *
 **/

void start_benchmark(struct config *config)
{
        unsigned int _round, cycle;
        long long now, then;
        long sleep_time = 0, load_time = 0;
        long performance_time = 0, powersave_time = 0;
        unsigned int calculations;
        unsigned long total_time = 0, progress_time = 0;

        sleep_time = config->sleep;
        load_time = config->load;

        /* For the progress bar */
        for (_round = 1; _round <= config->rounds; _round++)
                total_time += _round * (config->sleep + config->load);
        total_time *= 2; /* powersave and performance cycles */

        for (_round = 0; _round < config->rounds; _round++) {
                performance_time = 0LL;
                powersave_time = 0LL;

                show_progress(total_time, progress_time);

                /* set the cpufreq governor to "performance" which disables
                 * P-State switching. */
                if (set_cpufreq_governor("performance", config->cpu) != 0)
                        return;

                /* calibrate the calculation time. the resulting calculation
                 * _rounds should produce a load which matches the configured
                 * load time */
                calculations = calculate_timespace(load_time, config);

                if (config->verbose)
                        printf("_round %i: doing %u cycles with %u calculations"
                               " for %lius\n", _round + 1, config->cycles,
                               calculations, load_time);

                fprintf(config->output, "%u %li %li ",
                        _round, load_time, sleep_time);

                if (config->verbose)
                        printf("average: %lius, rps:%li\n",
                                load_time / calculations,
                                1000000 * calculations / load_time);

                /* do some sleep/load cycles with the performance governor */
                for (cycle = 0; cycle < config->cycles; cycle++) {
                        now = get_time();
                        usleep(sleep_time);
                        ROUNDS(calculations);
                        then = get_time();
                        performance_time += then - now - sleep_time;
                        if (config->verbose)
                                printf("performance cycle took %lius, "
                                        "sleep: %lius, "
                                        "load: %lius, rounds: %u\n",
                                        (long)(then - now), sleep_time,
                                        load_time, calculations);
                }
                fprintf(config->output, "%li ",
                        performance_time / config->cycles);

                progress_time += sleep_time + load_time;
                show_progress(total_time, progress_time);

                /* set the powersave governor which activates P-State switching
                 * again */
                if (set_cpufreq_governor(config->governor, config->cpu) != 0)
                        return;

                /* again, do some sleep/load cycles with the
                 * powersave governor */
                for (cycle = 0; cycle < config->cycles; cycle++) {
                        now = get_time();
                        usleep(sleep_time);
                        ROUNDS(calculations);
                        then = get_time();
                        powersave_time += then - now - sleep_time;
                        if (config->verbose)
                                printf("powersave cycle took %lius, "
                                        "sleep: %lius, "
                                        "load: %lius, rounds: %u\n",
                                        (long)(then - now), sleep_time,
                                        load_time, calculations);
                }

                progress_time += sleep_time + load_time;

                /* compare the average sleep/load cycles  */
                fprintf(config->output, "%li ",
                        powersave_time / config->cycles);
                fprintf(config->output, "%.3f\n",
                        performance_time * 100.0 / powersave_time);
                fflush(config->output);

                if (config->verbose)
                        printf("performance is at %.2f%%\n",
                                performance_time * 100.0 / powersave_time);

                sleep_time += config->sleep_step;
                load_time += config->load_step;
        }
}