Arch Linux

Zaphod

Member

Registered: 2014-03-14

Posts: 3

[SOLVED] pam_limits.so and jack realtime scheduling

Hi,

I'm trying to start jackd using realtime scheduling. Running:

$ jackd -R -dalsa 

I get:

jackdmp 1.9.9.5
Copyright 2001-2005 Paul Davis and others.
Copyright 2004-2012 Grame.
jackdmp comes with ABSOLUTELY NO WARRANTY
This is free software, and you are welcome to redistribute it
under certain conditions; see the file COPYING for details
Cannot create thread 1 Operation not permitted
Cannot create thread 1 Operation not permitted
Cannot create thread 1 Operation not permitted
JACK server starting in realtime mode with priority 10
Cannot lock down 82274202 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

Output of ulimit -f:

unlimited

Output of ulimit -r:

0

I have consulted the jack and realtime process management wikis (https://wiki.archlinux.org/index.php/JA … leshooting and https://wiki.archlinux.org/index.php/Realtime_for_Users) as well as followed the suggestions on the jack webpage (http://jackaudio.org/linux_rt_config) and two archforum posts (https://bbs.archlinux.org/viewtopic.php?id=115812 and https://bbs.archlinux.org/viewtopic.php?pid=387214) but I cannot get it to work.

As far as I can tell, the problem is that the module pam_limits.so is not loaded on login.

Output of grep pam_limits.so /etc/pam.d/*

/etc/pam.d/crond:session   required    pam_limits.so
/etc/pam.d/polkit-1:session         required        pam_limits.so
/etc/pam.d/system-auth:session   required  pam_limits.so
/etc/pam.d/system-services:session   required    pam_limits.so

When appending the following to /etc/pam.d/su I can get it to work if I open a terminal, su to my regular user, and then run jackd

 session    required    pam_limits.so

But I'm guessing there must be an easier way around this, namely, loading the pam module on login.

I've tried putting the above code in /etc/pam.d/login but that does not work.

Any suggestions?

I should add: I am not using a graphical login manager but log in from the console (and running startx); and yes, my user is in the audio group.

Cheers!

Last edited by Zaphod (2014-05-09 08:31:37)

Zaphod

Member

Registered: 2014-03-14

Posts: 3

Re: [SOLVED] pam_limits.so and jack realtime scheduling

I have still not been able to figure this one out. However, I have found out that if I run:

$ ulimit -r

outside of X, everything seems to be working just fine, i.e. I get the expected output 99.

So, it seems it is related to X, somehow, or some program run at X startup. My /.config/openbox/autostart:

## OPENBOX AUTOSTART ##

numlockx &

(sleep 1s && compton --config /home/user/My_Compton.conf) &

nitrogen --restore &

(sleep 2s && conky -c /home/user/Conky.txt) &

spacefm -d &

tint2 -c /home/user/My_tint2rc &

(sleep 1s && alsa-tray) &

My .xinitrc:

#!/bin/sh
#
# ~/.xinitrc
#
# Executed by startx (run your window manager from here)

if [ -d /etc/X11/xinit/xinitrc.d ]; then
 for f in /etc/X11/xinit/xinitrc.d/*; do
   [ -x "$f" ] && . "$f"
 done
 unset f
fi

[[ -f ~/.Xresources ]] && xrdb -merge ~/.Xresources
export GTK2_RC_FILES="$HOME/.gtkrc-2.0"
/usr/bin/xscreensaver -no-splash &
exec openbox-session

Any ideas or suggestion on where to look or how I might go about trying to find a solution would really be much appreciated.

Cheers!

Zaphod

Member

Registered: 2014-03-14

Posts: 3

Re: [SOLVED] pam_limits.so and jack realtime scheduling

Ok, after some time playing around with this, I seem to have narrowed down the problem - and found a workable solution!

It turns out to be a problem with pam_limits.so not being set (I'm not sure about the appropriate terminology here) for my urxvt-terminal. More specifically, I'm running the urxvtd daemon and launching my terminals in Openbox using the keybind Super+t (set up according to this: https://wiki.archlinux.org/index.php/Rx … in_Openbox).

However, running ulimit -r from xterm and a regularly launched urxvt (that is, not urxvtc) gives the expected result (99) and jack starts with realtime scheduling

If anyone knows how to set up urxvtd with the appropriate pam_limits, please let me know.

Cheers!

Marking thread as SOLVED.