append16k.c

#define _GNU_SOURCE
#define O_DIRECT        00040000ULL
#define O_ATOMIC        040000000ULL

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

int main ()
{
   FILE *fp;
   int fd;
   char *str;

   str = (char *) malloc(16384);
   memset(str,0,16384);
   fd = open( "./append16kb.txt" , O_DIRECT | O_WRONLY | O_TRUNC | O_ATOMIC);

   while (1)  {
      write(fd, str, 16384);
      fdatasync(fd);
   }

   close(fd);
   return(0);
}