My question of the using of fifos was not in respect of fifos themselves but rather why do you need the speed? Would it not be easier using the serial port? Or maybe a faster cpu? I got trapped many years ago when I did a multiprocessor system, I used spi to transfer the data between the cpus. The problem was not the speed of transfer but rather how I had divided up the problem. Whilst it worked, certain functions took too long due to scheduling the transfer.

Fifos are probably much faster than the cpu can keep up with and they are expensive - you can buy a much faster cpu for the cost of a fifo! Conceptually, all you do is write out a packet of data to the fifo without having to poll then the other end just reads a packet of data then processes it. The processing is the slow bit normally and may just offset the speed you gained using fifos.

So if you really need hi speed data transfer then fifos may be your best solution.