[ardour-dev] Ardour lab

[Paul Davis]

>Question:  I ran top on both machines while recording, and the CPU usage 
>is always 50-95%+ for ardour (the value gets split pretty evenly with X 
>until ardour is minimized, then ardour takes it all), but qjackctl and 
>ardour both show a common, very low value, always under 10%.  Is there 
>any rhyme or reason here?

the number reported by JACK (visible in qjackctl and ardour) is not
the total CPU usage of ardour or even all JACK clients. its the
fraction of available CPU cycles used to run a process cycle, averaged
and smoothed over some interval. it should perhaps be labelled "DSP
Load" or something like to make this clearer.

because of our use of SCHED_FIFO, you could theoretically have the DSP
code using just a few percent of the available cycles, but have the
GUI and other parts of one or more JACK clients uses all other cycles.

--p