While I think these things are super interesting trivia, I really want to ask the question: "Why does a Director of Engineering for Google need to know this?" That is not only a rather unusual question (within the scope of daily tasks for a programmer, these tend to be an important minority for a project), but it's one that's best settled empirically and within the context of your execution environment.
There are a lot of different answers to the question depending on where you're doing it and how you want to impact the machine.
It's a bizarre question to pose to Director level, because the proper response even for a technical director should be, "The answer to that changes quickly, we should measure and check what our environment's latest capabilities are and if they are reliable."
I mean I'm all gung ho to program stuff, but I think that'd be a massive misapplication of my time with that title in my current job, and given my other responsibilities I'd only do it more slowly than someone with dedicated focus.