MuLab over 20% system cpu on start (new default project), but shows 1% inside application. Question.

[LYTZ]

Hey guys,

just was checking stuff and in my activity monitor Mulab (fresh start, empty default project, just basic synth in it, idle) averages 20-21% cpu on the system activity monitor.

In mulab however the CPU meter averages 1%. Is the system CPU that mulab uses some kind of "buffer" or something? Or is it maybe that there is so much going on behind the curtains that this is normal behaviour? If so then that is still some heavy processing when idle.

Startet Bitwig side-to-side to see whats going on by the way. BW averages 1.3%. both in system cpu
and inside the applications CPU meter.
Can somebody clarify why that is?

(And yes, I tried setting the windows process priority from high back to normal, marginal difference.
(Idles on 19.5-20% when default) When setting to realtime, I see over 25%. I also changed multithreading to different numbers. Obviously no difference, because empty project.)

This is with an intel xeon mac pro 3.33 ghz 6-core 2014 model on OSX 10.9.4

Thanks,

tL.

[LYTZ]

By the way, can it be the case that the percentage numbers in the activity monitor do not show the real CPU processing but show which application takes the highest percentage of the processing, which might be way lower?

EDIT: Nah, I googled a bit, it is real CPU processing on a per-core basis.

[MuTools]

The CPU meter only measures the audio processing. It's the proportion of time needed to process an audio block per available time per audio block. The available time per audio block is the audio engine blocksize divided by the samplerate. For example using a 512 blocksize with a 44100 Hz samplerate gives 11.6 ms per block. If the measured amount of processing would be (average) 3 ms per block that gives a audio CPU usage of 25.8%. Note that the CPU meter does not measure the CPU used by the UI nor the CPU used by disk streaming or any other activities, only the audio processing. The audio CPU usage measuring is indicative and might not be 100% accurate as it depends on the system's accuracy for measuring the time needed to process an audio block.

Updated the relevant doc page: http://www.mutools.com/info/docs/mulab/transport.html

[MuTools]

When starting a new MuLab project, i don't see such a big difference between the MuLab cpu meter and what Windows is reporting in the task manager. Sounds like something system specific.