This is a program designed initially to speed up writing tapes on remote
tape drives, but may be used as a general pipe buffering utility.
Note: You must have SYSVSHM support in FreeBSD kernel.

The program splits itself into two processes.  The first process reads
(and reblocks) from stdin into a shared memory buffer.  The second
writes from the shared memory buffer to stdout.  Doing it this way
means that the writing side effectly sits in a tight write loop and
doesn't have to wait for input.  Similarly for the input side.  It is
this waiting that slows down other reblocking processes, like dd.