[PD] Latency under Linux/Jack (again...)

[Bernardo Barros]

Don't run programs as root, your system will be as insecure as a windows box...
Just allow rt privileges to the audio group, and add yourself to this group.
Then start jack with rt privileges. All software linked to Jack will
run with -rt.

from http://jackaudio.org/faq

JACK requires real-time scheduling privileges for reliable,
dropout-free operation. The server requests these privileges when
running with the -R option.

Most recent distributions use PAM to manage the permissions of users
on a relatively granular level. If the file /etc/security/limits.conf
exists on your system, it is using PAM. In order to configure PAM such
that normal users can run jackd with realtime privileges make sure the
following lines exist:
@audio   -  rtprio     99
@audio   -  memlock    unlimited


2010/10/12 Pedro Lopes <pedro.lopes at ist.utl.pt>:
> If you start pd in sudo, you have to connect to jack in sudo mode. Thus
> start jack in sudo (or gksudo for qjackctl).
> I advise to use an rt kernel too. See documentation of Ubuntu Studio.
>
> On Tue, Oct 12, 2010 at 3:27 PM, Raphael Raccuia
> <rafael.raccuia at blindekinder.com> wrote:
>>
>> Hi list,
>> I tested Pd rt as I need low latency for a performance next week...
>> It seems -rt flag doesn't have any effect. I measured Pd latency with
>> jdelay, and always get 640 (@48000), so about 13ms (pd only)... lower I
>> set buffer in jack (no less than 256), more DIO errors I get... and
>> there are a lot! This setting works great with many application
>> (Ardour...), with about 10ms (~15 really). So I would have ~25ms, which
>> is acceptable, but too many DIO errors!
>>
>> -what is -defeatrt setting? (I tried 0 and 1, no change)
>> -why is -rt flag without effect?
>> -tried nosleep, no change...
>>
>> I also tried to start pd in root (sudo)...
>>
>> It says:
>> priority 8 scheduling enabled.
>> priority 6 scheduling enabled.
>> (which I normally don't have)
>>
>> but unfortunately can't connect to jack (state 17)
>>
>> thank's for your help
>>
>>
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>
>
>
> --
> Pedro Lopes (ongoing MSc)
> contact: pedro.lopes at ist.utl.pt
> website: http://web.ist.utl.pt/Pedro.Lopes
>
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