FS#57416 - [linux][linux-lts] Jack audio barely usable due to xruns

Attached to Project: Arch Linux
Opened by Rainer Schaue (void42) - Wednesday, 07 February 2018, 14:31 GMT
Last edited by Andreas Radke (AndyRTR) - Wednesday, 21 March 2018, 13:33 GMT
Task Type Bug Report
Category Kernel
Status Closed
Assigned To Tobias Powalowski (tpowa)
Andreas Radke (AndyRTR)
Jan Alexander Steffens (heftig)
Architecture x86_64
Severity Low
Priority Normal
Reported Version
Due in Version Undecided
Due Date Undecided
Percent Complete 100%
Votes 2
Private No

Details

Description:
Since upgrading to 4.15.1-2 the Jack audio server reports a lot of xruns caused by applications feeding audio to jack, system audio is routed to jack via alsa_out:

Wed Feb 7 10:42:24 2018: ERROR: JackAudioDriver::ProcessGraphAsyncMaster: Process error
Wed Feb 7 10:42:32 2018: ERROR: JackEngine::XRun: client = alsa_out was not finished, state = Triggered
Wed Feb 7 10:42:32 2018: ERROR: JackAudioDriver::ProcessGraphAsyncMaster: Process error
Wed Feb 7 10:42:36 2018: ERROR: JackEngine::XRun: client = audacious was not finished, state = Triggered
Wed Feb 7 10:42:36 2018: ERROR: JackAudioDriver::ProcessGraphAsyncMaster: Process error
Wed Feb 7 10:42:36 2018: ERROR: JackAudioDriver::ProcessGraphAsyncMaster: Process error
Wed Feb 7 10:42:36 2018: ERROR: JackAudioDriver::ProcessGraphAsyncMaster: Process error
Wed Feb 7 10:42:36 2018: ERROR: JackAudioDriver::ProcessGraphAsyncMaster: Process error
Wed Feb 7 10:42:36 2018: ERROR: JackAudioDriver::ProcessGraphAsyncMaster: Process error
Wed Feb 7 10:42:36 2018: ERROR: JackAudioDriver::ProcessGraphAsyncMaster: Process error
Wed Feb 7 10:42:36 2018: ERROR: JackAudioDriver::ProcessGraphAsyncMaster: Process error
Wed Feb 7 10:42:40 2018: ERROR: JackEngine::XRun: client = alsa_in was not finished, state = Triggered

Which leads to a lot of noticeable clicks and even audio distortion.
No warnings are displayed in the syslog.

Increasing Buffersize/Latency (from 64 * 2 to 512 * 2) seems to reduce the xruns somewhat but there are still many.

I also tried to install linux-lts (4.14.17). Which behaves the same.

Sound card is an RME Digi9652 (Rev 1.5) (PCI).

After downgrading to 4.14.15-1 the issue is gone, the downgrading includes nvidia drivers but i cannot imagine how that would change things.

Additional info:
tested with:
* linux-4.15.1-2
* linux-lts-4.14.17-1
* jack2-1.9.12-1

Jack command line used:
/usr/bin/jackd -P89 -dalsa -r44100 -p64 -n2 -D -Chw:R15,0 -Phw:R15,0 -I12 -O12

Soundcard: RME Digi9652 (Rev 1.5)
Driver: snd_rme9652

At least another user reported similar behaviour in the arch subreddit.




This task depends upon

Closed by  Andreas Radke (AndyRTR)
Wednesday, 21 March 2018, 13:33 GMT
Reason for closing:  Fixed
Additional comments about closing:  fixed for stock kernel and not a bug for -lts kernel.
Comment by Rainer Schaue (void42) - Thursday, 08 February 2018, 06:42 GMT
CONFIG_PREEMPT is not set in 4.15.1-2
Comment by Andreas Radke (AndyRTR) - Thursday, 08 February 2018, 15:04 GMT
Linux-lts is not meant to run on (real)time critical systems. It's mainly optimised for server and conservative usage and as fallback for any other system.
PREEMPT will never be enabled in lts config.
Comment by Rainer Schaue (void42) - Thursday, 08 February 2018, 18:06 GMT
That is very intersting i did not now that. I'm not against it either since i don't use it anyway.
I tried to read up on it but i can't really find any disadvantages with enabling CONFIG_PREEMPT.
Do you mind to explain what is gained by not having CONFIG_PREEMPT?
Comment by Rainer Schaue (void42) - Saturday, 10 February 2018, 08:04 GMT
The issue has been resolved in linux-4.15.2-2

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