cpu goes wild on multi thread

Hi there, vcv runs pretty good and all stable with one core on linux. as soon as i want to give it multicore, the cpu usage goes crazy and i get a cpu fan concert here :wink: cpu usage would go on an empty patch from 1% to 450% … any ideas what this could be?

did you try it, with just an audio-module loaded?

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rsmus7: I just tried it: with just the audio module the cpu usage also goes up, but not crazy: it goes from 1,5% to 5%…

Which CPU performance scaling governor - “powersave” or “ondemand” ? CPU percentage may fluctuate because CPU freq is changing to meet demand.

If not allready using it - try changing to “performance”.

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This doesn’t account for the very high usage, but be aware should should use the minimum number of threads necessary for any patch. Increasing threads carries its own overhead. Having excess threads can experience higher CPU usage than a patch with fewer threads. And you always need an Audio module for proper performance.

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the governor is set to performance.

@PaulPiko you mean an external sound card? i m just on the internal one, also with pulseaudio. I prefer using jack but somehow pulse works smoother with vcvrack here…

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I mean one of the VCV Audio modules

image

ah ok yeah i got that!

thanks all for your help, seems a simple update and reboot solved the problem for now!! fingers crossed it s not coming back :slight_smile:

Hi there, some time later, I wrongly marked this thread as solved as it worked well for a little bit, but the problem persists actually on all of my machines: When I go from Threads 2 to higher I immediately get dropouts in the audio. It happens on my old thinkpad x220 but as well n my new powerful multicore machine from tuxedocomputers. I dont know what i could try. I disabled frequency scaling and use other audio software and video editing software in real time with no problems. Thanks for any kind of hint!

Normally it goes like this :

Start with as few threads as you can until the sound breaks up, add an extra thread, continue to add more modules until the sound breaks up, add an extra thread etc. Starting with 8 or more threads works counter-intuitive ; it will up the CPU use.

yeager thanks, that is what I am doing. also playing with latency times etc. but “the best” performance I always get with two threads, and on my tiny laptop the limit there is like 3 modules, when I add more modules it gets glitchy, when I then add another thread , the glitches become more, not less. …

Ok, that is NOT how it should work. So I guess something else is wrong here.

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Read about how Rack performance works:

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ah fantastic, this is the info i was looking for, thank you!! I guess this applies 100% for linux machines.

I have a dedicated nvidia graphics card and i was also thinking that an external sound card could make the audio handling more smooth, i will test it soon with a focusrite interface and see if that would give me less xruns than the internal audio output.