Note the classic 'bus lock' is a worst case nowadays: caches in SMP machines have their own protocols for invalidating and locking individual lines, so the enti

Note the classic 'bus lock' is a worst case nowadays: caches in SMP machines have their own protocols for invalidating and locking individual lines, so the entirety of the machine's memory isn't necessarily serialized, though I'm not sure when this kind of locking applies.