I assume that the usb keyboard driver is completely different code and is unlikely to have the same problem. (One would expect the generic usb implementation t

I assume that the usb keyboard driver is completely different code and is unlikely to have the same problem. (One would expect the generic usb implementation to be more carefully designed, since there are so many kinds of usb devices, each with their own unique ways of causing or being adversely affected by scheduling latency.) I haven't done the test, though. In general, this sort of problem is less of an issue now since the transition to multi-core processors means that a long-held spinlock doesn't actually block all progress on the machine. There are usually plenty of other available cores and it's unlikely that unrelated processes are all stuck at the same time.