real time kernel not real time, still xruns in Jackd
 

Hi

I am having trouble with interruptions and xruns in Jackd. I had hundrets of xruns in Jackd before on the non real time kernel (standard Debian, Lenny 5.0). Now I went through the pains to compile my own real time (preempt) and STILL not success, music playback still jerks from time to time. Xruns are still there, although this computer (a thinkpad T61, Dualcore 2 x 2.4 ghz) should be able for flawless playback.

The xruns are regular, about every 1 minute there is a audible jerk and after about 20 minutes of listening to music, I have raked up almost 100 xruns.

How can I find out what is causing this? is there something wrong with the IRQs on my system? Graphic card driver? The Nvidia card ( Quadro NVS 140M ) uses a proprietary one (*shudder*), and although it should be able to handle compiz with nothing as a shrug, it runs it like a pig (very low framerate, jerky cube rotation). Might this be the culprit?
Even my little Asus eee can do smooth cube rotation, and that one has a shared graphics card, the NVIDIA is 10 times more powerful than that.

*Clueless*

Markus