constant xruns

[rube2112]

Hi, I have 5 different computers that I've tried to get jack working on. I've tried ubuntu studio, mint, and a few others. It's always the same story no matter which os or which computer I use. After install, Jack works perfectly and I can get very low latency, then in a few days, it just starts giving solid xruns.....38 frames at a time, not intermittently, but constantly. This never stops no matter what settings I try. I can put it on 4096 10, and it's still the same thing. This usually is triggered when a daw starts jack on it's own. Once this starts, I can never get it to work again no matter what I try until I reinstall the os. I can't find a jack troubleshooting page....this was the closest thing I could find. Thanks....Robb

[lilith]

Did you make all optimizations?

There a realtimeconfig script that checks your settings. I would start from here: https://github.com/raboof/realtimeconfigquickscan
It's strange though that it starts after some days. Are you using Laptops or Desktop PCs?

[rube2112]

No i haven't made any optimizations. I've been unable to find any documentation at all. That's why I'm here. Robb

[khz]

Welcome,

I've been unable to find any documentation at all.

you will find a small overview in my 2 notes (see signature).

[lilith]

Setting the CPU governor to performance is quite crucial. Run the script from above and post the output here.

[rube2112]

here it is....

[lilith]

Check point 1. and 2. from here

https://jackaudio.org/faq/linux_rt_config.html

You are already in the audio group, so point 2 is not needed.

And then set the CPU governor to performance. I guess that should already improve it.

Maybe start from here
https://forums.linuxmint.com/viewtopic.php?t=297413

It can be different from distro to distro.

[ycollette]

Which RT kernel do you run ?
Which graphic card do you have ?

I met some similar problem a while ago with a recent RT kernel. That was a problem with the AMD graphic card and some lock in the kernel.s
I had constant xruns after kernel upgrade.

[dailybug2]

Hello - here my observations regarding Jack "the XRUN" D.:

I'm using jackd on Ubuntu 20.04 with MusE and Audacity (for testing jackd only).
Audio interface: Behringer XENYX302USB (nothing special, think of a standard USB interface, duplex-capable).

Constant XRUNs every 10.22 seconds (yes, exactly 10.22!)
- with Audacity only when recording; playback is OK.
- with MusE all the time if the transport is rolling.

Tried a lot of tips I found in the web - no effect except for increased knowledge.
Played with the Jack config, exaggerated buffer settings (512 / 4 buffers / 50 msec latency) - no effect.

Then I had the "stupid" idea do test with "realtime = off" et voila, SOLVED!
This is ODD, jackd screws up I/O if realtime=on!? Does if "take real time" in this case?

I guess things are not that simple and something went wrong with the prios. Here a process/thread list for the insiders:

Code: Select all

> ps ax -L -o pid,ni,rtprio,comm | egrep -i 'command|muse|jack'
    PID  NI RTPRIO COMMAND
   1790   0      - jackdbus
   1790   0      - jackdbus
   1790   0      - jackdbus
   1790   -     10 jackdbus
   1790   0      - jackdbus
   2032   0      - qjackctl
   2032   0      - qjackctl:rcs0
   2032   -      0 qjackct:disk$0
   2032   -      0 qjackct:disk$1
   2032   -      0 qjackct:disk$2
   2032   -      0 qjackct:disk$3
   2032   0      - qjackctl
   2032   0      - qjackctl
   3022   0      - muse-fast-start
   3023   0      - muse3
   3023   0      - muse3
   3023   0      - muse3
   3023   0      - muse3
   3023   0      - muse3:rcs0
   3023   -      0 muse3:disk$0
   3023   -      0 muse3:disk$1
   3023   -      0 muse3:disk$2
   3023   -      0 muse3:disk$3
   3023   -      5 muse3
   3023   0      - muse3
   3023   -      4 muse3

[dailybug2]

Then I had the "stupid" idea do test with "realtime = off" et voila, SOLVED!
This is ODD, jackd screws up I/O if realtime=on!? Does if "take real time" in this case?

No, not solved. With jackd/realtime=off there are still XRUNs every 1..2 minutes, not related to the buffer size. I had to go on with my "stupid" experiments.

In the meantime I moved my PC from here to there and the XRUNs are ... GONE, even with jackd/realtime=on! Whotttttf?!

Cause: I connected the USB interface to the back of the PC now, because of the cable length. Either the front connection is weak and catches interference (bad ground!), or the USB port is handled inadequately by the BIOS or Linux. Strange that I was able to copy an entire hard-disk via this port without issues.

I scanned the web for such USB port issues and yes, there is the advice to try different ports.

TLDR; if your USB interface causes cyclic sporadic XRUNs, try a different port. Use the front USB ports, if any, for keyboard and mouse only.