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Jack DSP performance recorder/chart


While working on performance enhancement on RaspberryPi I am often not really sure if my activities lead to enhancements or make things worse.
To get a clear picture I would like to record DSP performance (and XRUN count). For reproducible results I would like to have

* When rolling starts: Chart/recorder is reset
* During rolling: Chart/recorder active / x-axis is time in seconds synchronized to Jack's frames.
* When rolling stops, recorder is frozen

Up to now my google search did not show up some application yet... So my questions here:

1. Is there some Jack client app able to something like this?
2. If not: In case I implement a third tab in qjackctl's Messages / Status window (QtCharts would be my friend here): Would such a change find other friends?

Thanks in advance


rncbc's picture

as much I can tell there is none for the wide public at least.

there were more than one kind of such charting tickers, during the early (bad old) days, meaning the first XXI century decade, when jackd were instrumental for the development of the early low-latency 2.6 kernel (PREEMPT) and then then voluntary-preemptive move which was the direct ancestor to the now known as real-time kernel patch (PREEMPT_RT).

but that's now history and swept away by the dusty sands of oblivion... :)

anyway, now that we're almost nigh into the third decade, is bad old qjackctl still a thing? I know half of the world still rely on it, but let me humbly ask: is this old piece of junk still worthy?

never mind. You're of course welcome to add a xrun ticker/scrolling chart to qjackctl.

by all means.

although I would rather prefer that these two things happen first and in this order:
1) jackctl API ported to jack1 (as is from jack2 currently);
2) completely rewrite qjackctl to use exclusively this native jackctl API, instead and abstracting the jack1 hocus-pocus unix process juggling and also the infamous jack2 d-bus interface for x sake.

that couple would be neat and get my full stamp of approval and blessing ;)

but don't stop it there, please.

all the above complaints have nothing to do with your proposal.
again, you're welcome and all hands and brains are too.


Hmm - this is a bit of an unexpected answer. I use/like qjackctl because:

* After baking a new SDCard for Raspi - which is necessary sometimes - it is the perfect tool for me to setup jack.
* I can add a2jmidid autostart if I want to play keyboard on ardour easily
* It displays performance numbers / XRUNS

Honestly: For a rewrite my skills are not (yet) sufficient and again I am happy with it - sorry at least not now.

Just out of curiosity: Is performance no issue on average PCs these days? My experiences here are limited: Raspi (I am fighting for every CPU-cylce and Megabyte) / debugging on PC which does not have RT-Kernel and causes sometimes XRUNS even if running qjackctl / jack only (no problem for me - its not my target).

Related to the performance chart: Due to licence of qtcharts (GPLv3) I would prefer qwt - see how far I get.

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