[arch-proaudio] limits.conf for jack

David Runge dave at sleepmap.de
Wed Dec 27 15:25:20 UTC 2017

On December 27, 2017 1:31:42 PM GMT+01:00, Ralf Mardorf <ralf.mardorf at alice-dsl.net> wrote:
>I prefer to stay with the audio group for rtprio and memlock,
>since migrating to a new group wouldn't be an advantage for me and only
>would cause work, e.g. rewriting scripts that check if a user is in the
>audio group or fixing scripts that chown' a directory or file for
Maybe you misunderstood me here, Ralf. The realtime group is merely my suggestion, which stands for discussion of course.
This is why I wrote the mail and not just dumped a change on your head.
The required settings are very jack specific and in no way does it make sense to maintain them twice (in jack and jack2).

Having a separate group from "audio" [1] for the realtime settings for jack/jack2 might be debatable, I agree, but it surely is the cleaner and more modular solution.
The acquiring of those limits is bound to groups, that either are created by the filesystem package [2], or by a dedicated package (although I'm still wondering where the audio group is actually being created currently).
By Arch embracing systemd-sysusers, this has become properly packageable (not fumbling with creation/deletion of users and groups in install files).
So, if anything, using a group called "realtime" or "jack" or whatever for these limits would actually be more specific.

Changes like these sadly sometimes come with minor breakage (and changes do occur).
However, I think doing a search/replace on a bunch of scripts can't be too hard for an adept user, such as yourself, if this change is properly documented.

>realtime users. Anything useful for those using pulseaudio, skype or
>similar crap is not related to the needs of realtime audio
>workstation users. It's a PITA that this rubbish (to care about
>pulseaudio and skype in the context of a realtime audio
>workstation) gains more and more ground, while there is lean manpower
>for the Linux pro-audio domain. A good reason to migrate to another OS
>for pro-audio, if Linux pro-audio development attracts less attention,
>than bonding counter-productive software. I had doubts to completely
>migrate to a restricted OS for pro-audio, even while I already use a
>combination of Linux and Pear, but I get more and more convinced that
>this soon or later becomes the lesser evil.
I'm not sure what you are trying to get at here though. I agree, that pulse and skype (even more so) should not be considered in the implementation of realtime settings for jack.
However, Arch Linux provides the means to create systems, that fit your purpose. For some people it might be to dump pulse output in a jack sink. As this is intended behavior, especially when using the jack2-dbus package, this is a use-case, that has to be considered, too.

You might not like this, but other people do have different setups from yours. This does not, will not and should not prevent you from running a rock solid pro-audio system on Arch!
We are currently en route to adopting more pro-audio related packages for [community] (after fixing the outstanding ones) and improving their usage.
So there (hopefully) really is  not much of a reason to rant about it.


[1] https://wiki.archlinux.org/index.php/Users_and_groups#Pre-systemd_groups
[2] https://git.archlinux.org/svntogit/packages.git/tree/trunk/sysusers?h=packages/filesystem


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