Thanks for the links! Yeah I assumed it would originate cache coherency protocol as well. In that case, it's not hard to figure out "when" to invalidate, as yo

Thanks for the links! Yeah I assumed it would originate cache coherency protocol as well. In that case, it's not hard to figure out "when" to invalidate, as you just invalidate the cacheline on mutates based on addresses. If cache invalidation originates from cache coherency protocols, I would assume Phil Karlton's quote was not referring to the "when" to invalidate as being the hard problem. But I will not die on this hill. I am open to rephrase/redefine/reword in anyway that is helpful to people.