The question says it all. I see some tutorials online for earlier editions of Ubuntu, but am having a hard time for 12.04.
There is generally no need to adjust IRQ priority unless you are having particular problems and want to apply boot options such as
However, you are probably referring to the hwtools package that was available before even Hardy (8.04) and which contained the
However, there is a program in the repositories called irqbalance, which is designed only for multi-core CPUS. There is more information here, but it may not be appropriate for you as it is more to do with balancing server load.
If you want to list your IRQ ports in Ubuntu you can run
Questions like this are very important when running pro audio applications. As you see, and as I have experienced myself many times in the past, Askubuntu.com has a tendency to tell us that we don't need an answer to these kinds of questions. For these narrowly focused questions, you'll find more friendly help on places like the LinuxMusicians forum or the OpenSourceMusicians IRC channel (# opensourcemusicians).
I run KX Studio (which is a pro audio distribution on top of Kubuntu) and I have gotten a lot of help at both #kxstudio and #ardour IRC channels.
Anyway, here's how you do it now that I have figured it out with help from the above resources.
Use these commands to discover the USB bus and IRQ of your audio device:
In my case, my USB audio interface is ehci_hcd:usb2 on IRQ 23. It may not be easy to figure it out, but if you cross reference the above listings you'll figure out which IRQ is of interest after some detective work. See below for more tips.
Next, install rtirq
Now edit the file /etc/default/rtirq (as sudo). And look for the line that contains
If you want IRQ 23 to have the highest priority, add it to the front of the list like so:
However, in my case, I would rather use the name of the device in case the IRQ assignment changes for some unknown reaason. So I specify it like this:
Just put the device (or IRQ) at the front of the list for highest priority. It is a space delimited list.
Save the file, then run:
There is no need to reboot. You'll see the resulting IRQ priorities listed from the command above. But if you want to see them again later, run:
Some extra tips, as promised:
I also used
You might also find the following Perl script useful: