One of the JACK developers reported this problem on LKML and the reply was very interesting, this could explain a lot of the weird latency issues that laptop users are seeing. http://lkml.org/lkml/2004/10/11/182 The basic issue seems to be if your laptop has a broken BIOS which implements ACPI using SMM you are out of luck. Here is some more information on the problem (near the end of the page): http://www.infoworld.com/cgi-bin/displayNew.pl?/glass/bg112596.htm If ACPI causes you massive xrun/latency problems then you might have such a broken BIOS. If you are having weird latency problems with a laptop, even with ACPI disabled, try to see if it corresponds to the fan turning on or changing speed. If so then you might be screwed :-( There does not seem to be a lot of hope if you do have one of these broken machines. But we can at least identify the problematic laptops, complain to the manufacturers, and warn people not to buy them. Lee
