Is that core count right for the big instance? The same cpu is used on the data-heavy nodes [1] and it says it maxes out at 36 cores. Or does amazon save some cores for their own uses on those boxes?
There doesn't seem to be any official specifications for the Xeon E5-2676 v3, probably because it's a custom CPU made just for Amazon.
Random sources found via Google seem to suggest that they have somewhere between 10 and 12 cores, which would translate to between 40 and 48 hyperthreaded vCPU's with a dual-socket setup.
So perhaps Amazon has found a way to set aside fewer (or no) cores for their own uses on the new m4 lineup. Or maybe it's the other way around and the data-heavy nodes require more cores to be set aside than usual.
Yeah, it is possible that amazon does the latter there. Save some virtual cores for their own purposes to dedicate towards parity, etc, to get IO higher.
[1] https://aws.amazon.com/blogs/aws/next-generation-of-dense-st...