You need to enable kernel preemption in the kernel features section and the realtime LSM (Linux Security Model) in the Security section. For it to be enabled, you have to uncheck (I don't know why) the "common linux capabilities". I don't have the latest 2.6.12, but a 2.6.12-rc4 patched with the mm patch. However I still have serious xrun problems even with fairly large periods (512, even 1024). I later found two possible causes of this problem, which are independent of the kernel: 1) If you have an independent kernel module, such as the semi-closed one that NVidia provides, it is clearly not patched for realtime! This is my case. Maybe for audio I should use the nv module included in the kernel distribution. 2) The video card assigns itself the maximum priority in the PCI bus, while the USB or the onboard audio (I have an onboard intel8x0 chipset and I use an external MAudio MobilePre USB) have the lowest possible priority on the bus. Thus, during even naive graphic operations (such as the raising of a window), I get xruns. Nor to mention if I run glxgears or something like that. This can be fixed using the "setpci" command to force a lower priority on the video card and to raise the audio. I didn't try this yet, but it's promising. Of course, you'd get worse graphics performance, but you don't want both things at the same time do you? These are my advices. Please (anyone) try them and tell me if it made a difference. I'll test them myself when I have some time. Regards, Ignacio.- Christoph Eckert wrote: