[LAU] Intel-hda jack low latency howto

Nathanael Anderson wirelessdreamer at gmail.com
Sun Nov 2 11:28:08 EST 2008

A intel-hda jack low latency howto (by wirelessdreamer)

I've seen asked many times on the list how to get intel-hda cards working
with low latency, in duplex operation. Here is a full, step by step, on how
I got 4ms latency. I'm using a Dell M90 with a Quadro fx 1500, attached to a
docking station with a Maudio Delta 66 pci card (secondary card) in it, the
binary Nvidia drivers and Compiz. So if you were wondering, it is possible.

1. Kernel (i'm not going to walk you through how to compile a kernel)

(the last kernel before the big kernel lock regression)
* wget http://www.kernel.org/pub/linux/kernel/v2.6/linux-

* tar xvjf linux-
* cd linux-

(if you don't see it here look in the projects/rt/older/ directory)
* wget

* bzcat ../patch-

* wget http://pastebin.com/pastebin.php?dl=f6ad31838
* mv pastebin.php\?dl\=f6ad31838 .config.old
* make oldconfig

(build and install your kernel)

2. Module Options
Add the following line to the file your distribution has its module options
(in ubuntu it is /etc/modules.d/alsa-base)

options snd-hda-intel model=ref position_fix=1 enable=1 index=0

3. Mixer Options (VERY IMPORTANT ! ! !)
enable capture/record elements in mixer
without this jack can't play nicely with intel-hda cards

4. RT Permissions
In most modern distros /etc/security/limits.conf is where realtime
permissions are set, I added these 3 lines to it, and added myself to the
@audio group in /etc/group

@audio          -       memlock         1024000
@audio          -       nice            -10
@audio          -       rtprio          99

5. Jack options
I use qjackctl to set these

put a check in Realtime
Priority 89
Frames/Period 64
Sample Rate 48000
Periods/Buffer 3
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