[ISSUE] jack cannot use realtime scheduling

[ISSUE] jack cannot use realtime scheduling

[VoidDuck]

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New issue by VoidDuck on void-packages repository

https://github.com/void-linux/void-packages/issues/20051

Description:
Hello,

I tried many different settings but I definitely cannot get jack to run with realtime priority on Void, while it works fine on other distributions.

I checked everything described on https://jackaudio.org/faq/linux_rt_config.html and https://github.com/jackaudio/jackaudio.github.com/wiki/Cgroups but it still does not work.

Here is what I get when running `jackd -R -d alsa`:

> JACK server starting in realtime mode with priority 10
> self-connect-mode is "Don't restrict self connect requests"
> Cannot lock down 82280346 byte memory area (Cannot allocate memory)
> audio_reservation_init
> Acquire audio card Audio0
> creating alsa driver ... hw:0|hw:0|1024|2|48000|0|0|nomon|swmeter|-|32bit
> configuring for 48000Hz, period = 1024 frames (21.3 ms), buffer = 2 periods
> ALSA: final selected sample format for capture: 32bit integer little-endian
> ALSA: use 2 periods for capture
> ALSA: final selected sample format for playback: 32bit integer little-endian
> ALSA: use 2 periods for playback
> Cannot use real-time scheduling (RR/10) (1: Operation not permitted)
> AcquireSelfRealTime error

### System
* xuname:  
  *Void 5.4.24_1 x86_64 GenuineIntel uptodate rF*
* package:  
  *jack-1.9.14_1*

Re: jack cannot use realtime scheduling

[VoidDuck]

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New comment by VoidDuck on void-packages repository

https://github.com/void-linux/void-packages/issues/20051#issuecomment-598756307

Comment:
For your information, I just tried the same in a root session and it works perfectly there, so the problem definitely is on the user permissions side.

Re: jack cannot use realtime scheduling

[daniel-eys]

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New comment by daniel-eys on void-packages repository

https://github.com/void-linux/void-packages/issues/20051#issuecomment-598821053

Comment:
Your user is definitely added to the audio group?
```sh
groups | grep audio
```

Re: jack cannot use realtime scheduling

[VoidDuck]

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New comment by VoidDuck on void-packages repository

https://github.com/void-linux/void-packages/issues/20051#issuecomment-598826774

Comment:
Yes.

Re: jack cannot use realtime scheduling

[daniel-eys]

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New comment by daniel-eys on void-packages repository

https://github.com/void-linux/void-packages/issues/20051#issuecomment-598830639

Comment:
What's the output of `ulimit -l` for your user?
It should output `unlimited`.

Re: jack cannot use realtime scheduling

[jrigg]

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New comment by jrigg on void-packages repository

https://github.com/void-linux/void-packages/issues/20051#issuecomment-598883168

Comment:
What happens if you do
`export JACK_NO_AUDIO_RESERVATION=TRUE`
before starting jackd? That disables jackdbus and runs plain jackd.

I have the above set permanently in .bashrc and jackd has always worked properly with realtime priority on my Void system. 

Re: jack cannot use realtime scheduling

[jrigg]

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New comment by jrigg on void-packages repository

https://github.com/void-linux/void-packages/issues/20051#issuecomment-598883168

Comment:
What happens if you do
`export JACK_NO_AUDIO_RESERVATION=TRUE`
before starting jackd? That disables jackdbus and runs plain jackd.

I have the above set permanently in .bashrc and jackd has always worked properly with realtime priority on my Void system.  I didn't have to do any special configuration apart from setting that environment variable.

Re: jack cannot use realtime scheduling

[VoidDuck]

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New comment by VoidDuck on void-packages repository

https://github.com/void-linux/void-packages/issues/20051#issuecomment-598952802

Comment:
> What's the output of `ulimit -l` for your user?
> It should output `unlimited`.
I get `64`...


> What happens if you do
> `export JACK_NO_AUDIO_RESERVATION=TRUE`
> before starting jackd?
Nothing special. I get the same output as usual.

Re: jack cannot use realtime scheduling

[VoidDuck]

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New comment by VoidDuck on void-packages repository

https://github.com/void-linux/void-packages/issues/20051#issuecomment-598952802

Comment:
> What's the output of `ulimit -l` for your user?
> It should output `unlimited`.

I get `64`...


> What happens if you do
> `export JACK_NO_AUDIO_RESERVATION=TRUE`
> before starting jackd?

Nothing special. I get the same output as usual.

Re: jack cannot use realtime scheduling

[daniel-eys]

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New comment by daniel-eys on void-packages repository

https://github.com/void-linux/void-packages/issues/20051#issuecomment-598959076

Comment:
> I get `64`...

This is the issue here.
The jack package installs `/etc/security/limits.d/jack.conf` which permits the audio group to access higher resource limits:
`@audio	-	memlock	unlimited`.

After adding your user to the audio group, have you logged out and in again for the change to take effect?

Re: jack cannot use realtime scheduling

[VoidDuck]

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New comment by VoidDuck on void-packages repository

https://github.com/void-linux/void-packages/issues/20051#issuecomment-598964777

Comment:
Definitely, my user has been in the audio group since I installed the system.

In `/etc/group` I have `audio:x:12:myuser`

In `/etc/security/limits.d/jack.conf` I have
`@audio  -       rtprio  99`
`@audio  -       memlock unlimited`

Re: jack cannot use realtime scheduling

[daniel-eys]

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New comment by daniel-eys on void-packages repository

https://github.com/void-linux/void-packages/issues/20051#issuecomment-598974747

Comment:
And you did a re-login after adding your user to audio? (There needs to be a new session such that pam picks up and sets all limits)
Have you manually changed `memlock` within `/etc/security/*` perhaps somewhere?
Memlock should be set to unlimited for all audio group members.

Re: jack cannot use realtime scheduling

[daniel-eys]

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New comment by daniel-eys on void-packages repository

https://github.com/void-linux/void-packages/issues/20051#issuecomment-598974747

Comment:
And you did a re-login after adding your user to audio? (There needs to be a new session such that pam picks up and sets all limits)
Have you manually changed `memlock` within `/etc/security/*` perhaps somewhere?
Memlock should be set to unlimited for all audio group members (when jack is installed).

Re: jack cannot use realtime scheduling

[daniel-eys]

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New comment by daniel-eys on void-packages repository

https://github.com/void-linux/void-packages/issues/20051#issuecomment-598974747

Comment:
Because there needs to be a new session such that pam picks up and sets all limits, that's why it's important to re-login after adding a user to the audio group.
Have you manually changed `memlock` within `/etc/security/*` perhaps somewhere?
Memlock should be set to unlimited for all audio group members.

Re: jack cannot use realtime scheduling

[daniel-eys]

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New comment by daniel-eys on void-packages repository

https://github.com/void-linux/void-packages/issues/20051#issuecomment-598974747

Comment:
Because there needs to be a new session such that pam picks up and sets all limits, that's why it's important to re-login after adding a user to the audio group.
Have you manually changed `memlock` within `/etc/security/*` perhaps somewhere?
Memlock should be set to unlimited for all audio group members (when jack is installed).

Re: jack cannot use realtime scheduling

[VoidDuck]

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New comment by VoidDuck on void-packages repository

https://github.com/void-linux/void-packages/issues/20051#issuecomment-598976577

Comment:
Don't worry, I have been logging in and out dozens of times in my attempts to get jack working properly...

The only other memlock-related setting I can find in `/etc/security` is `limits.d/10-gcr-memlock.conf`:
`# Increate max locked memory to 1024KB for the users group.`
`@users - memlock 1024`

Re: jack cannot use realtime scheduling

[VoidDuck]

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New comment by VoidDuck on void-packages repository

https://github.com/void-linux/void-packages/issues/20051#issuecomment-598976577

Comment:
Don't worry, I have been logging in and out dozens of times in my attempts to get jack working properly...

The only other memlock-related setting I can find in `/etc/security` is `limits.d/10-gcr-memlock.conf`:
> `# Increate max locked memory to 1024KB for the users group.`
> `@users - memlock 1024`

Re: jack cannot use realtime scheduling

[daniel-eys]

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New comment by daniel-eys on void-packages repository

https://github.com/void-linux/void-packages/issues/20051#issuecomment-598990967

Comment:
Right, this restricts the group `users` to limit memlock to 1024KB.
But you said your memlock limit is still at 64. (which is definitely the issue here)
I'm not really sure why jack.conf is not properly picked up and setting memlock to unlimited. :/
Are you able to manually `ulimit -l unlimited`?

Re: jack cannot use realtime scheduling

[VoidDuck]

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New comment by VoidDuck on void-packages repository

https://github.com/void-linux/void-packages/issues/20051#issuecomment-599031499

Comment:
No, it does not work either.
`bash: ulimit: max locked memory: cannot modify limit: Operation not permitted`

Re: jack cannot use realtime scheduling

[daniel-eys]

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New comment by daniel-eys on void-packages repository

https://github.com/void-linux/void-packages/issues/20051#issuecomment-599089667

Comment:
I'm running a bit out of ideas here.
Fresh void iso, logging in as `anon` user (anon is in the audio group)

```sh
[anon@void-live ~]$ ulimit -l
64
```

After installing `jack` and re-login:

```sh
[anon@void-live ~]$ ulimit -l
unlimited
```

Are there maybe any `ulimit`s set in your global bash-setup?
Any modifications within `/etc/pam.d/`?

Re: jack cannot use realtime scheduling

[VoidDuck]

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New comment by VoidDuck on void-packages repository

https://github.com/void-linux/void-packages/issues/20051#issuecomment-599112537

Comment:
I could not find anything related in /etc/pam.d/ nor in my bash settings.

However I tried logging in as user in text mode and there `ulimit -l` gave me `unlimited` indeed. Back to the graphical interface (I use Xfce and LightDM) I get `64` again... may the problem come from LightDM?

Re: jack cannot use realtime scheduling

[VoidDuck]

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New comment by VoidDuck on void-packages repository

https://github.com/void-linux/void-packages/issues/20051#issuecomment-599146673

Comment:
That's it! If I start Xfce from command line without using LightDM I keep the unlimited memlock. Unless someone has an idea about solving that problem I'm just getting rid of LightDM. Thank you @daniel-eys for your help.

Re: [ISSUE] [CLOSED] jack cannot use realtime scheduling

[VoidDuck]

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Closed issue by VoidDuck on void-packages repository

https://github.com/void-linux/void-packages/issues/20051

Description:
Hello,

I tried many different settings but I definitely cannot get jack to run with realtime priority on Void, while it works fine on other distributions.

I checked everything described on https://jackaudio.org/faq/linux_rt_config.html and https://github.com/jackaudio/jackaudio.github.com/wiki/Cgroups but it still does not work.

Here is what I get when running `jackd -R -d alsa`:

> JACK server starting in realtime mode with priority 10
> self-connect-mode is "Don't restrict self connect requests"
> Cannot lock down 82280346 byte memory area (Cannot allocate memory)
> audio_reservation_init
> Acquire audio card Audio0
> creating alsa driver ... hw:0|hw:0|1024|2|48000|0|0|nomon|swmeter|-|32bit
> configuring for 48000Hz, period = 1024 frames (21.3 ms), buffer = 2 periods
> ALSA: final selected sample format for capture: 32bit integer little-endian
> ALSA: use 2 periods for capture
> ALSA: final selected sample format for playback: 32bit integer little-endian
> ALSA: use 2 periods for playback
> Cannot use real-time scheduling (RR/10) (1: Operation not permitted)
> AcquireSelfRealTime error

### System
* xuname:  
  *Void 5.4.24_1 x86_64 GenuineIntel uptodate rF*
* package:  
  *jack-1.9.14_1*

Re: jack cannot use realtime scheduling

[daniel-eys]

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New comment by daniel-eys on void-packages repository

https://github.com/void-linux/void-packages/issues/20051#issuecomment-599148013

Comment:
Interesting, so lightdm caused this.
Looking at `/etc/pam.d/lightdm`, lightdm seems to delegate pam to `pam_elogind.so` (?), but I don't really know where/when/how elogind sets limits for its sessions.
One workaround would be to explicitly load `pam_limits` (the pam module responsible for setting resource limits) by adding

`session required pam_limits.so`

to `/etc/pam.d/lightdm`, like so:
```
...
# Setup session
session   required pam_unix.so
session   required pam_limits.so
-session   optional pam_elogind.so
-session optional pam_ck_connector.so nox11
```

So with this added, you could actually continue using lightdm. @VoidDuck

Re: jack cannot use realtime scheduling

[VoidDuck]

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New comment by VoidDuck on void-packages repository

https://github.com/void-linux/void-packages/issues/20051#issuecomment-599148962

Comment:
It works. Thank you very much!

In this case I think that line should be added to the default `/etc/pam.d/lightdm` shipped in Void.
Are you able to do this or should I open another issue about it?

Re: jack cannot use realtime scheduling

[daniel-eys]

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New comment by daniel-eys on void-packages repository

https://github.com/void-linux/void-packages/issues/20051#issuecomment-599155763

Comment:
You're welcome, glad to hear that it works :)

My issue here is that I'm not really sure whether this is "the proper" fix to be included in the lightdm package. This was more like my first thought how it might work and it actually did.
For example, there is also polkit which handles `pam_limits`, maybe it's elogind's job to set session limits, `gdm` and `slim` add `session include system-local-login`, which (after some redirections) pulls in `pam_limits` via `system-auth`, I'm still a bit confused here.