[LAU] realtime kernel on ubuntu 8.04

[hollunder at gmx.at]

On Tue, 02 Sep 2008 08:14:02 +0200
Atte André Jensen <atte.jensen at gmail.com> wrote:

> Hi
> 
> My old thinkpad running ubuntu 7.10 died and I'm now on a new laptop 
> (toshiba satellite) with ubuntu 8.04.
> 
> I'm having alot of trouble getting good realtime performance, not
> sure what's caused by ubuntu or the laptop.
> 
> I installed "linux-rt" which seems to have provided some kind of 
> realtime kernel:
> atte at vestbjerg:~$ uname -r
> 2.6.24-19-rt
> 
> I also edited /etc/security/limits.conf to contain:
> @audio - prio 99
> @audio - rtprio 99
> @audio - nice -10
> 
> I can run jack with rt-priority 80, but am getting x-runs and audio 
> breakup even at light load and conservative latency  (17ms).
> 
> One of the things I have a feeling might be causing trouble is 
> pulseaudio. Should this be disabled, and if so how?
> 
> What else am I missing?
> 
> NB: I'm mostly testing this with eXT2, which performed great on my
> thinkpad.
> 
> NB2: This is a dualcore, 2Ghz, 2Gb ram machine with a fresh ubuntu
> 8.04
> 
> Any ideas appreciated
> 

The most important piece of information when it comes to audio troubles
is missing: audio interface?
The next one: jack settings?
In case you're using you laptops on-board sound chip and it is a HDA
Intel, use periods/buffer 3.
If you do use the on-board-thing, 17ms is not conservative.

> @audio - prio 99
This one is new to me. I don't know if it hurts but it is certainly not
necessary.
What you missed are memlock settings,
there's a nice app that will allow you to set it as %, called
'Ubuntustudio Controls', and I recommend to set it to 76% (to stop
ardour from complaining).

Best Regards,
	Philipp