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

From: Joakim Hernberg <jhernberg@email-addr-hidden>
Date: Thu Sep 04 2014 - 17:09:18 EEST

On Thu, 4 Sep 2014 09:03:55 -0400
"Peter P." <p8rpp@email-addr-hidden> wrote:

> 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.

qjackctl's "DSP load" refers to how much of the latency given by
samplerate and buffersize has been used up by the audio processing
callback. That is to say if you have 2.9ms to finish the audio
processing, and the callback takes 1.45ms, then it will
show 50%, if it takes 2.9ms then it will show 100%. Note that it's an
average and not a maximum number, so conventional wisdom is to keep it
under 60% or so, to avoid xruns (ymmw).

The flashing RT just indicates that JACK is running in rt mode.

-- 
   Joakim
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Received on Thu Sep 4 20:15:01 2014

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