On Tue, Aug 9, 2016 at 2:41 PM, Ffanci Silvain <silvain@freeshell.de> wrote: 
for a few months now my jackd1 (0.121.3) takes on a lot of CPU, even with no clients connected.

Are there any connections like system:capture -> system:playback?
 
Normally JACK stays below 2% though.

If it "builds" over time, is it linear, or is it around 2% for a long time, and then builds to 90% or so?
It smells a bit of floating point denormal-processing, if its creeping up after a while of not being used. I don't know if/why JACK is performing floating ops unless there are buffers that need to be combined...

system cap1 \
system cap2 -  system play1
system cap3 /

The above might explain it though - routing multiple inputs to one output.
 
Any idea, why this CPU-hunger might creep up? Things to look into? I'd be very grateful for hints.

The above is a "shot in the dark", but as far as I can see it could be a cause.

HTH! -Harry 

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