[Jackaudio] Jack & systemd on RPI4

[pfl]

yeah I had setup the priorities in /ets/security/limits.conf

I noticed this could be setup in the systemd service itsef, thanks for 
the example service, quiet neat

I'll retry running it as realtime, but now I am busy playing with 
different synth and trying to make routing without qjackctl


On 12/05/2020 20:59, David Runge wrote:
> Hi Phil,
>
> On 2020-05-12 20:37:40 (+0200), pfl wrote:
>> in the mean time, I ended up running it as 'pi' user
>>
>> with an extra Environement="XDG_RUNTIME_DIR=/run/user/1000"
> Yeah, running a **system** service as a user (using the `User=`
> directive) might also work, as long as you get the required directories
> in line.
>
>> but I never achieved to make it run in -R mode
>>
>> I use ExecStart=/usr/bin/jackd -r -d alsa -r 44100 -P
> Have a look at the realtime related settings in the upstream user
> service [1].
> They are also applicable to **system** services and basically allow your
> service to use realtime scheduling priority of up to 95. Otherwise any
> service either defaults to a setting from its parent or the system-wide
> default (set by your distribution).
> To read more about those settings, have a look at the upstream
> systemd.exec documentation [2].
> Note, that for an unprivileged user you have to allow said user to use a
> specific realtime scheduling priority (e.g. 95) and unlimited memlock.
> On Arch Linux we have started making this available via the `realtime`
> user group [3] (on other distributions it's sometimes coupled to the
> `audio` group) by installing a configuration drop-in to
> /etc/security/limits.d/.  However, this can also be set for your
> specific user only (see /etc/security/limits.conf for the syntax).
>
> Best,
> David
>
> [1] https://github.com/jackaudio/jack2/blob/develop/systemd/jack%40.service.in#L11-L13
> [2] https://www.freedesktop.org/software/systemd/man/systemd.exec.html#Process%20Properties
> [3] https://git.archlinux.org/svntogit/community.git/tree/trunk/99-realtime-privileges.conf?h=packages/realtime-privileges
>

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