[LAU] what is jackd "DSP load"? Blinking "RT" indicator?

[Peter P.]

Hi,

after many years of wondering now and then I am curious what
qjackctl's display of "DSP load" is supposed to mean?
It must be some kind of CPU load, as there is no dedicated DSP in my
computer, so is it the cpu load of the jackd process?
Furthermore I wonder why the realtime "RT" indicator in qjackctl's
window is blinking about every 2 seconds. I do have -rt enabled.

Thank you for helping me to find answers to these things that are
puzzling me since quite some time.

best, P