sd_bench.c

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/**
 * @file sd_bench.c
 *
 * SD Card benchmarking
 */

#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <unistd.h>

#include <px4_platform_common/px4_config.h>
#include <px4_platform_common/module.h>
#include <px4_platform_common/getopt.h>
#include <px4_platform_common/log.h>

#include <drivers/drv_hrt.h>

static void usage(void);

/** sequential write speed test */
static void write_test(int fd, uint8_t *block, int block_size);

/**
 * Measure the time for fsync.
 * @param fd
 * @return time in ms
 */
static inline unsigned int time_fsync(int fd);

__EXPORT int    sd_bench_main(int argc, char *argv[]);

static const char *BENCHMARK_FILE = PX4_STORAGEDIR"/benchmark.tmp";

static int num_runs; ///< number of runs
static int run_duration; ///< duration of a single run [ms]
static bool synchronized; ///< call fsync after each block?

static void
usage()
{
    PRINT_MODULE_DESCRIPTION("Test the speed of an SD Card");

    PRINT_MODULE_USAGE_NAME_SIMPLE("sd_bench", "command");
    PRINT_MODULE_USAGE_PARAM_INT('b', 4096, 1, 1000000, "Block size for each read/write", true);
    PRINT_MODULE_USAGE_PARAM_INT('r', 5, 1, 1000, "Number of runs", true);
    PRINT_MODULE_USAGE_PARAM_INT('d', 2000, 1, 100000, "Duration of a run in ms", true);
    PRINT_MODULE_USAGE_PARAM_FLAG('s', "Call fsync after each block (default=at end of each run)", true);
}

int
sd_bench_main(int argc, char *argv[])
{
    int block_size = 4096;
    int myoptind = 1;
    int ch;
    const char *myoptarg = NULL;
    synchronized = false;
    num_runs = 5;
    run_duration = 2000;

    while ((ch = px4_getopt(argc, argv, "b:r:d:s", &myoptind, &myoptarg)) != EOF) {
        switch (ch) {
        case 'b':
            block_size = strtol(myoptarg, NULL, 0);
            break;

        case 'r':
            num_runs = strtol(myoptarg, NULL, 0);
            break;

        case 'd':
            run_duration = strtol(myoptarg, NULL, 0);
            break;

        case 's':
            synchronized = true;
            break;

        default:
            usage();
            return -1;
            break;
        }
    }

    if (block_size <= 0 || num_runs <= 0) {
        PX4_ERR("invalid argument");
        return -1;
    }

    int bench_fd = open(BENCHMARK_FILE, O_CREAT | O_WRONLY | O_TRUNC, PX4_O_MODE_666);

    if (bench_fd < 0) {
        PX4_ERR("Can't open benchmark file %s", BENCHMARK_FILE);
        return -1;
    }

    //create some data block
    uint8_t *block = (uint8_t *)malloc(block_size);

    if (!block) {
        PX4_ERR("Failed to allocate memory block");
        close(bench_fd);
        return -1;
    }

    for (int i = 0; i < block_size; ++i) {
        block[i] = (uint8_t)i;
    }

    PX4_INFO("Using block size = %i bytes, sync=%i", block_size, (int)synchronized);
    write_test(bench_fd, block, block_size);

    free(block);
    close(bench_fd);
    unlink(BENCHMARK_FILE);

    return 0;
}

unsigned int time_fsync(int fd)
{
    hrt_abstime fsync_start = hrt_absolute_time();
    fsync(fd);
    return hrt_elapsed_time(&fsync_start) / 1000;
}

void write_test(int fd, uint8_t *block, int block_size)
{
    PX4_INFO("");
    PX4_INFO("Testing Sequential Write Speed...");
    double total_elapsed = 0.;
    unsigned int total_blocks = 0;

    for (int run = 0; run < num_runs; ++run) {
        hrt_abstime start = hrt_absolute_time();
        unsigned int num_blocks = 0;
        unsigned int max_write_time = 0;
        unsigned int fsync_time = 0;

        while ((int64_t)hrt_elapsed_time(&start) < run_duration * 1000) {

            hrt_abstime write_start = hrt_absolute_time();
            size_t written = write(fd, block, block_size);
            unsigned int write_time = hrt_elapsed_time(&write_start) / 1000;

            if (write_time > max_write_time) {
                max_write_time = write_time;
            }

            if ((int)written != block_size) {
                PX4_ERR("Write error");
                return;
            }

            if (synchronized) {
                fsync_time += time_fsync(fd);
            }

            ++num_blocks;
        }

        //Note: if testing a slow device (SD Card) and the OS buffers a lot (eg. Linux),
        //fsync can take really long, and it looks like the process hangs. But it does
        //not and the reported result will still be correct.
        fsync_time += time_fsync(fd);

        //report
        double elapsed = hrt_elapsed_time(&start) / 1.e6;
        PX4_INFO("  Run %2i: %8.2lf KB/s, max write time: %i ms (=%7.2lf KB/s), fsync: %i ms", run,
             (double)block_size * num_blocks / elapsed / 1024.,
             max_write_time, (double)block_size / max_write_time * 1000. / 1024., fsync_time);

        total_elapsed += elapsed;
        total_blocks += num_blocks;
    }

    PX4_INFO("  Avg   : %8.2lf KB/s", (double)block_size * total_blocks / total_elapsed / 1024.);
}