I am having trouble to understand --realtime on linux. It seems to work more reliably, but has unwanted side-effects when doing other kinds of IO. Specifically, working with the serial opcodes turns to be very problematic. I am working in a project where an arduino is used as a DAC, sending serial information of 12 light sensors at a fixed rate of 2000 Hz. The rate needs to be high, since this sensors operate on the audio stream by amplitude modulation. When running without --realtime, I get a very reliable sampling rate between the arduino and csound, but sometimes get xruns when in heavy load. With --realtime csound never glitches, but the sampling rate drops dramatically.