Using the time built-in command of the shell, try timing the operation of the program in Listing 4-1 (copy.c) on your system.

a) Experiment with different file and buffer sizes. You can set the buffer size using the DBUF_SIZE=nbytes option when compiling the program.

b) Modify the open() system call to include the O_SYNC flag. How much difference does this make to the speed for various buffer sizes?

c) Try performing these timing tests on a range of file systems (e.g., ext3, XFS, Btrfs, and JFS). Are the results similar? Are the trends the same when going from small to large buffer sizes?