Re: [LAU] xrun problems. (Was Re: Introduction to Ardour 3.0 MIDI)

From: Hartmut Noack <zettberlin@email-addr-hidden>
Date: Wed Mar 30 2011 - 14:19:07 EEST

Am 28.03.2011 23:15, schrieb Dan Capp:
> Hi Peder. Thanks for your assistance. Info below:
>
>> What CPU do you have (grep "model name" /proc/cpuinfo)?
>
> AMD Phenom(tm) 9750 Quad-Core Processor

I had a Presonus Firebox running with Frames/Periods 64/3 on a ancient
Pentium4 with zero xruns. The very same Firebox spat out xruns by the
score if running it on a Lenovo Laptop with Intel Dualcore with 256/3.

Firewire Interfaces tend to be very picky regarding the chipset oft the
FW-Controller:

http://ffado.org/?q=node/251

  and they amok, if there is something on the bus blocking them.

>
>> Have you made the limits.conf hack to enable realtime and are you
>
> I'm afraid I have no idea.

the file /etc/security/limits.conf should have the following lines at
its end:

@audio - rtprio 86
@audio - memlock unlimited

in Ubuntu there is a file called "audio.conf" in a folder named
/etc/security/limits.d . In Fedora the file is called 99jack.conf.

All with the same lines. You need to be member in the group "audio" (or
"jackuser" under Fedora)

> I have a real-time kernel and I have it set to on
> when I use firewire, but off when I use alsa. All music production (when I
> get the one-off xruns) happens only when using firewire, and thus with
> realtime on.
>
>> running jack in realtime (with say -P70)?
>
> Yes I have jack in realtime, on exactly P70, but ONLY in firewire mode. Alsa
> mode is set to default priority and non-realtime. I have QjackCtl setup so
> that it launches and starts in Alsa-mode when I boot my computer. When I do
> music stuff and turn my firewire device on I switch to the "firewire" preset
> which is realtime P70.
>
>> Are you running jack with ?ber-low latency; what's the frames/period
> setting?
>
> In firewire mode I have frames/period setting of 256 with buffer on 3 = a
> latency of 17.4 msec.

On a system like yours any Firewire-Interface should do much better (see
above).

Ever tried a Live-DVD like AVLinux or Pure:Dyne?

> Alsa mode is much higher on 1024 and around 70 msec
> (but I believe that should be irrelevant as I don't do any audio/midi jack
> connection stuff in Alsa mode.
>
> -Dan
>
>
>
>
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Received on Wed Mar 30 16:15:03 2011

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