[PD] Raspberry Pi & pd 0.46 with real time priority

katja katjavetter at gmail.com
Thu Dec 11 18:19:10 CET 2014

On Xubuntu 12.04 I found the same /etc/security/limits.d/audio.conf
file with rtprio 95 specified for the audio group. So this setting
must be around for quite a while, and not limited to Debian /
Raspbian. I can't find any documentation or even mailing list
discussion explaining the rationale.

Miller has today responded to this fait accompli with the release of
pd 0.46-3 which respects that level, so it can't be bothered by
jackd's default setting. Thanks Miller! This irons out a lot of the

By the way I found that when I created
/etc/security/limits.d/puredata.conf it has precedence over
/etc/security/limits.d/audio.conf, probably because of it's
alpha-numerical rank. Would this for pd users be the most transparent
option to set real time priority? Or am I overlooking some drawback?


On Thu, Dec 11, 2014 at 1:32 PM, Kaj Ailomaa <zequence at mousike.me> wrote:
> On Wed, Dec 10, 2014, at 04:23 PM, katja wrote:
>> On Wed, Dec 10, 2014 at 11:31 AM, Kaj Ailomaa <zequence at mousike.me>
>> wrote:
>> >
>> >
>> > On Wed, Dec 10, 2014, at 02:45 AM, katja wrote:
>> >> /etc/security/limits.d/audio.conf, with the following content:
>> >>
>> >> @audio   -  rtprio     95
>> >> @audio   -  memlock    unlimited
>> >> #@audio   -  nice      -19
>> >>
>> >
>> > Doesn't this file come with jackd? Haven't checked on Raspbian, but this
>> > is the case on Debian.
>> > This works well on Debian, since user is member of audio group by
>> > default.
>> You're right Kaj, the file itself says it: 'provided by the jackd
>> package'. So it's not a Raspbian default. How could I miss that while
>> checking and tweaking the file a dozen times.
>> I wonder why the file sets real time priority 95, while official
>> jackaudio documentation
>> (http://jackaudio.org/faq/linux_rt_config.html) recommends level 99.
>> If level 95 is Debian tradition, it would be best for pd to comply
>> with that level.
>> Katja
> I think there are some different opinions on what is safe, but I
> wouldn't be able to explain the difference. That is just the way jackd
> has been packaged for a while I guess :).

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