Realtime group scheduling doesn't know JACK

> which latency is the concern?
The problem is with the latency between the moment a musician hits a key or a string, and the moment when he hears the result played back to him. This latency has to be low and predictable enough to be unnoticeable for a professional musician, who expects his new-fangled smart musical instrument with Linux inside to respond perceptually instantly, just like an old-fashioned mechanical device.