Hi all,
as announced before [1], recent changes to the jack and jack2{,-dbus}
packages (now in [extra] and [community] respectively) have made the
previously shipped configurations obsolete and decoupled the audio group
from acquiring realtime privileges by default when installing jack.
The package realtime-privileges [2] has been created to serve as the new
way of achieving this by the means of a dedicated 'realtime' group, to
which users, that need the settings, must be added.
It is now an optional dependency to jack and jack2{,-dbus} and can of
course also be dependend upon from other packages if needed.
In theory, this change shouldn't mean much of a difference to users,
that need realtime (just install realtime-priviliges and add your user
to the realtime group: `gpasswd -a <user> realtime`), while it doesn't
have any consequences for users that have no use for it to begin with.
Best,
David
[1] https://lists.archlinux.org/pipermail/arch-proaudio/2018-July/000163.html
[2] https://www.archlinux.org/packages/community/any/realtime-privileges/
--
https://sleepmap.de
aside from the new 'realtime' package, i would like to propose an audio-specific optimizations package of the sort that other av-centric distros commonly have - a package that contains goodies such as the 'realTimeConfigQuickScan' and 'rtirq' scripts that will inform the user how best to optimize their hardware IRQ and PCI latency and such; and other suggestions from the linuxaudio wiki[1] that can be automated, such as selectively disabling and re-enabling unnecessary services (screensaver, printing, *ehem* pulse), a .jackdrc with smaller buffers than the default config, etc
i did a side-by-side comparison with the analogous proaudio-settings optimization packages from each of parabola, kxstudio, and ubuntustudio - they are all nearly identical in what they accomplish; but AFAIK currently arch does not have an analogous package - here are some examples of what they do:
--------
using 'parabola-proaudio-settings'[2] as a reference:
# custom kernel parameters to sysctl.d folder
/etc/sysctl.d/99-sysctl.conf
# By default, swap frequency defined by "swappiness" is set to 60. By reducing this number to 10, the system will wait much longer before trying to write to disk
vm.swappiness = 10
# inotify watches for changes to files and reports them to applications requesting this information. When working with lots of audio data, a lot of watches will need to be kept track of, so they will need to be increased.
fs.inotify.max_user_watches = 524288
--------
# ensure the ALSA MIDI driver is loaded
/etc/modules-load.d//alsamidi.conf
# If you want to use any MIDI hardware you need to ensure the ALSA MIDI driver is loaded
snd_seq_midi
--------
# recommended initial settings for jack
/etc/jackdrc
/usr/bin/jackd -P89 -t2000 -dalsa -dhw:0 -r44100 -p256 -n2 -Xseq
--------
# systemd service
# increase the highest requested RTC interrupt frequency (default is 64 Hz)
/etc/systemd/system/parabola-proaudio-settings.service
/etc/parabola-proaudio-settings.sh
#!/bin/sh
echo 2048 > /sys/class/rtc/rtc0/max_user_freq
echo 2048 > /proc/sys/dev/hpet/max-user-freq
cpupower frequency-set -g performance
echo noop > /sys/block/sda/queue/scheduler
--------
# extra virtual midi ports
/etc/modprobe.d/snd-seq-dummy_16.conf
#Creates extra virtual midi ports
options snd-seq-dummy ports=8
--------
kxstudio 'kxstudio-default-settings'[3] has the following also:
/etc/sysctl.d/10-kxstudio-sysctl-rules.conf
dev.hpet.max-user-freq = 2048
--------
ubuntustudio 'ubuntustudio-default-settings'[4] suggests that 3072 is a better value for dev.hpet.max-user-freq (although they have it commented out)
#dev.hpet.max-user-freq=3072
--------
both kxstudio and ubuntustudio have the following also (this is the only concern that is specified in the new 'realtime' package):
/lib/udev/rules.d/99-kxstudio-udev.rules
/lib/udev/rules.d/40-timer-permissions.rules
KERNEL=="rtc0", GROUP="audio"
KERNEL=="hpet", GROUP="audio"
--------
[1]: https://wiki.linuxaudio.org/wiki/system_configuration
[2]: https://git.parabola.nu/abslibre.git/tree/pcr/parabola-proaudio-settings?id…
[3]: https://github.com/KXStudio/KXStudio/tree/master/default-settings
[4]: https://git.launchpad.net/ubuntustudio-default-settings/tree/