This example features two real-time tasks (rt1, rt2) that potentially 
can perform some useful work, e.g. data collection. Here they simply 
write strings into FIFOs. 

The Linux process (rttest) creates four FIFOs, two for data passing,
and another two for sending parameters (priorities, periods, start times)
to real-time tasks. It loads RT-programs in the memory, writes
parameters into the parameters FIFOs, starts the RT-processes, and enters 
the endless loop, waiting for data.

The real-time processes are almost identical. Each of them reads its parameters
from the FIFO, tells them to the RT-kernel, and gives up the CPU until
the start time. Then it enters the main loop in which it puts "data"
into the FIFO designated for the data passing.
In the end of each period it makes a request to deschedule itself
until the beginning of the next period using RTwait_period routine.
