I wondered why the same USB2 interface causes a different number of interrupts per second (cat /proc/interrupts) depending on which USB port of my computer it was connected. This means that on one USB port I could use a jack_bufsize not smaller than 96 but on another USB port I could use a jack_bufsize of 64.
As far as I have understood the xhci driver can tell the USB controller to collect data from USB devices and holds back interrupts for imod_interval * 250 nanoseconds.
What I didn't understand: How can I set the imod_interval? It can save some CPU if you don't need a very small jack_bufsize.