The "eatdata" command is logically equivalent to "cat >/dev/null", but faster, because it doesn't write the data.

The only command-line argument is a number, which is the buffer size. The default buffer size is 40960, due to restrictions in TCP. The buffer size will typically effect the speed; it won't have much effect on the speed of pipes, except for very small buffer sizes.

time eatdata </staging/foo.mpg

This tells you how fast a program can read data from a file on a particular disk (partition).

time gendata 5000000 | time eatdata

This generates 5 megabytes of data and pipes it to eatdata. The times printed give you an idea of the speed of I/O through a pipe on your machine.