"Regular" Linux is designed for a useful user experience. There are two (or more?) "Real Time Linux" distros that are designed to control hardware: RTLinux, and Real-Time Linux with PREEMPT_RT patches added to the kernel. I have not found details of benchmarks for these. How "real" is real? Millisecond response? Microsecond? Less?
I can imagine designing a PCIe card for network test; full throttle rapid packet speed test, but also (with some "simple" analog circuitry controlled by "real time" software, cable testing with nanosecond TDR (time delay reflectometry), using a technique resembling "count the falling dominos by the loudness of the clatter they make". That would require microsecond response in a tight realtime loop, controlling analog circuitry that converts microsecond intervals into brief nanosecond intervals. ( Also using an analog circuit technique called "dual slope", which we need not dwell on here ) A Cat 6 cable is 5 nanoseconds per meter, 10 ns down and back. Some degradations (such as RJ45 connectors) are smaller, but can add up and limit bandwidth. The right hardware and software might help network engineers observe and understand these fast phenomena, and cure some rather subtle gigabit-rate signalling and cabling problems. Keith L. -- Keith Lofstrom kei...@keithl.com
