Peter's Filesystem Simple Tester

This is really a super simple program that tests and measures the time certain
common operations take.

I personally use it to verify correct behaviour of NFS filesystems from multiple 
servers at the same time.

It basically does this test in a subprocess for each <dir> specified on the
command line:

while (forever || -n<loops>) {
   mkdir("t-$HOST-$PID");
   if (-c) {
     chdir("t-$HOST-$PID");
     fd = open("test1.dat", O_CREAT|O_WRONLY);
     write(fd, buf, 64K);
     if (-s)
       fsync(fd);
     close(fd);
     rename("test1.dat", "test2.dat");
     fd = open("test2.dat", O_RDONLY);
     read(fd, buf, 64K);
     close(fd);
     unlink("test2.dat");
     chdir("..");
   }
   rmdir("t-$HOST-$PID")
   sleep(1);
}


EXAMPLES:

Loop forever and alert if any of the operations take more than 30ms:

  ./pfst -c -t30ms /mnt/server1 /mnt/server2 /mnt/server3

Run one test of just the "mkdir/rmdir" operation and be verbose:

  ./pfst -n1 -v .


SOURCE:

	https://github.com/ptrrkssn/pfst

- Peter Eriksson, 2020-03-05, pen@lysator.liu.se