[linux-audio-user] Real-time kernel

Hartmut Noack zettberlin at linuxuse.de
Wed Nov 29 18:15:36 EST 2006


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Chuckk Hubbard schrieb:
> On 11/29/06, Mark Knecht <markknecht at gmail.com> wrote:
>> On 11/29/06, Chuckk Hubbard <badmuthahubbard at gmail.com> wrote:
>> > On 11/29/06, Hartmut Noack <zettberlin at linuxuse.de> wrote:
>> > > I agree, yet if you want some more desktop-ability and even less
>> work,
>> > > you can use ubuntu edgy eft plus this kernel:
>> > >
>> > > http://www.ubuntuforums.org/showthread.php?t=261821
>> > >
>> > > yes, this is 32bit, but you can of course install the sources and
>> > > recompile (whithout the need to patch it yourself) plus: if you
>> have a
>> > > deadline, you can run the 32bit Version after 1,5h of effort with
>> about
>> > > 2.8 ms latency and stable (as it works for me so far...)
>> >
>> > Well I have it running now, but jackd is set to 46 ms and I have 2
>> > dozen xruns a second...  I guess this is the part of my original
>> > problem that I still haven't figured out.
>> >
>>
>> Have you prioritixd your audio IRQs higher than others?
>>
>> If not then look for the rtirq script for doing that.
> 
> Thanks for the tip, I hadn't heard of this script.  I only just
> discovered IRQs, and was hoping to avoid them.  Alas, that will put me
> over the 1.5 hour mark, lol.  And RG is complaining about lack of MIDI
> sequencer.
> 
> -Chuckk
> 
So there are some 1 h more effort to be taken...
fast answers, no backgrounds:

1.) if the IRQ-script shall work, you must have your soundcard set
excluselively to an IRQ by using the BIOS-Setup, especially, if your
Sounddevice shares an IRQ with an active Harddrive, you will get xruns
even if you let Paul Davis himself set up you software for RT ;-)

2.) to make RG and MUSE happy, alsa-sequencer must be started:
:~$ sudo bash
password
:~# modprobe snd-seq
:~# echo snd-seq >> /etc/modules
:~# exit

3.) And rtc must:
	3.1.) belong to group audio (as yourself)
	3.2.) provide a usable resolution:
	
	Open a terminal and enter this:
		
		:~$ sudo bash
			password
		:~# echo 1024 > /proc/sys/dev/rtc/max-user-freq

The latter is no issue, if you want that being set each time you start
the system, put a line like this into /etc/init.d/bootmisc.sh (make sure
to have this on a new line and NOT between existing brackets...)

 echo 1024 > /proc/sys/dev/rtc/max-user-freq


If your card is on its own IRQ and you have applied the priority script
to that IRQ, xruns sould cease - if not, there is another problem to be
solved maybe someone else could help, yet I think, it can only be the
IRQ-Issue...

sorry for not pointing you to this stuff, I thought, you had found out
this already.
All this and more tutorials for tuning Ubuntu for Audio can be found here:

https://help.ubuntu.com/community/UbuntuStudioPreparation

you do not need to do everything, that is proposed here, just to start.
Once your card is set to its own IRQ situation should improve largely.
So you can tune your system further while having the fun to have it
basically working OK already ;-)



hope this helps, good luck :-)
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