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

[Raphael Raccuia]

Sorry, I didn't gave a lot of info:
-Intel core2duo T9500 (2.6 GHz)
-Ubuntu Lucid (32bit), with rt kernel (which is not rt, I never
understood this story...)
-last pd-ext from repo (which seems to be down since a while).
-RME Multiface I /HDSP expresscard

Of course jack run with -R. I repeat I don't have any problem to run
application with really good latency: yesterday, I forgot to increase
buffer as I worked on a 96000Hz Ardour session... I noticed I was
working at 5ms I/O after one hour recording and playing a lot of tracks,
and no xrun, no problems...
I also think it's not a good Idea to run pd as root... and I suppose
other application won't connect to jack if I run it as root also.

I noticed I had two times the @audio config (limits.conf, audio.conf).
You'll say: "better twice than nothing"... But maybe it generates a
conflict... I try

Le mardi 12 octobre 2010 à 11:50 -0300, Bernardo Barros a écrit :
> 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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> > UNSUBSCRIBE and account-management ->
> > http://lists.puredata.info/listinfo/pd-list
> >
> >