a prototype of microbenchmark for sequential write

sequential_write.c

#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/types.h>
#include <unistd.h>

inline void xgettimeofday(struct timeval *tv) {
    if (gettimeofday(tv, NULL) == -1) {
        perror("gettimeofday(2)");
        exit(EXIT_FAILURE);
    }
}

inline void xwrite(int fd, const void *buf, size_t count) {
    if (write(fd, buf, count) == -1) {
        perror("write(2)");
        exit(EXIT_FAILURE);
    }
}

inline void xfsync(int fd) {
    if (fsync(fd) == -1) {
        perror("fsync(2)");
        exit(EXIT_FAILURE);
    }
}

void do_write(int fd, size_t each_write_bytes, int count, struct timeval *tvs) {
    char *buffer = (char *) calloc(count, sizeof(char));
    if (buffer == NULL) {
        perror("calloc(3)");
        exit(EXIT_FAILURE);
    }

    xgettimeofday(&tvs[0]);
    for (int i = 0; i < count; i++) {
        xwrite(fd, buffer, each_write_bytes);
        xfsync(fd);
        xgettimeofday(&tvs[i + 1]);
    }

    free(buffer);
}

double to_f(struct timeval tv) {
    return tv.tv_sec + tv.tv_usec * 1e-6;
}

int main(int argc, char *argv[]) {
    const char *out_file = "/tmp/write.out";
    int each_write_bytes = 8192;
    int count = 1000;

    struct timeval *tvs = (struct timeval *) calloc(count + 1, sizeof(struct timeval));
    if (tvs == NULL) {
        perror("calloc(3)");
        exit(EXIT_FAILURE);
    }

    int fd = open(out_file, O_WRONLY | O_CREAT, 0664);
    if (fd == -1) {
        perror("open(2)");
        exit(EXIT_FAILURE);
    }

    do_write(fd, each_write_bytes, count, tvs);

    if (close(fd) == -1) {
        perror("close(2)");
        exit(EXIT_FAILURE);
    }

    printf("start: %f\n", to_f(tvs[0]));
    printf("end:   %f\n", to_f(tvs[count]));

    free(tvs);
    return 0;
}