write_bench.c

#define _GNU_SOURCE

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

int main (int argc, char *argv[])
{
  int file;
  unsigned int bs = 1024 * 1024 * 1; // 1MB
  uint64_t total_size = 1024 * 1024 * 1024 * 1ULL;
  int use_reopen = 1;
  int first_time = 1;
  uint64_t pos = 0;
  uint8_t *buf = NULL;
  int i;
  int ret;

  printf("close benchmark\n");

  if (argc < 2) {
    printf("lack of target path\n");
    exit(EXIT_FAILURE);
  }

  printf("target %s\n", argv[1]);

  /* must be align in O_DIRECT */
  if (posix_memalign((void **)&buf, 512, bs)) {
    perror("posix_memalign");
    exit(EXIT_FAILURE);
  }

  printf("trying to open...\n");
  if ((file = open(argv[1], O_WRONLY | O_DIRECT)) < 0) {
    perror("open\n");
    exit(EXIT_FAILURE);
  }
  printf("done\n");

  printf("writing buffer...\n");
  for (pos = 0 ; pos < total_size ; ) {
    ret = lseek(file, pos, SEEK_SET);
    if (ret == -1) {
      perror("lseek\n");
      exit(EXIT_FAILURE);
    }
    ret = write(file, buf, bs);
    if (ret < 0) {
      perror("write\n");
      exit(EXIT_FAILURE);
    }
    pos += ret;
  }
  printf("total pos was wrote: 0x%lx\n", pos);
    
  close(file);
  printf("done\n");
  
  return 0;
}