It looks like this is related to hal. When I moved aside /etc/dbus-1/event.d/20hal and restarted dbus, the interrupts stopped.
-- ohci_hcd driver causes interrupt flood, high load https://launchpad.net/bugs/80539 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
