How to gain latency less than 5ms

Installation & Configuration Linux
#1

I would like to know, did anybody succeeded to decrease latency under 5ms on Mandriva 2008 Spring Final.
My problem is that I don’t know how to run JACK with realtime privileges. I’m using a kernel with IngoMolnar rt-patches, but I’m not able to run Ardour with low latency ( 11 ms is still unacceptable).
Please, I need a detailed description.

Any ideas DrG ?

Thanks in forward

#2

Thanks friends!
That worked for me. I’ve recorded 7 stereo tracks with 5.3ms latency with maximum 0.59 ms system dump, and no xruns!
Thank’s again!

#3

Have you edited your /etc/security/limits.conf?

If not, enter (as root) in terminal:

echo @audio - rtprio 99 >> /etc/security/limits.conf
echo @audio - memlock 250000 >> /etc/security/limits.conf
echo @audio - nice -10 >> /etc/security/limits.conf

I don’t run Mandriva, but I run 5 ms no problems…also, what are your system specs?

mm0

#4

Intel Celeron-D 2.67 GHz 64-bits
1.5 GB Kingston DDRAM
Audigy 2
Running Mandriva 2008 Spring Final release.
I can’t run JACK server in realtime mode, it’s not permitted. I’ve tried different kernle flavours like mm and rt but no use.

#5

Ensure that your username is in the ‘audio’ group. (The edits to ‘limits.conf’ allow RT privileges for members of the audio group, but by default you will not be a member of that group). You can do this by the command line but I can’t remember how; there’s a ‘users and groups’ GUI tool in the Mandriva Control Centre for doing this. You may have to reboot afterwards.

NB, on Mandriva, editing limits.conf using the ‘echo’ way as described above may not work, since at least one of those lines is already there. You’ll be safer to use an editor to do it.

I’ve not tried it in 2008.1 but on 2008.0 I can get stable 2.7ms latency on my firewire adapter this way, although I’m running a faster system than you.