Intel Corp (INTC)

[ibc]

I'm pretty sure the Intel architects know more than you do.

SMT isn't free.

Going from 2 to 4 greatly increases the complexity of the thread picker. Instead of "pick one or the other", now you get into a quagmire of which one to pick. This could impact frequency as well as a bunch of other things.

Thread level parallelism in phone workloads is less than 2 (refer to any number of academic papers on the subject). Even for desktop workloads, the number is less than 3. It would not surprise me one bit to see Broxton go back to 1-thread per core.

Now Xeon-Phi is massively parallel, so yes, increasing SMT thread count there makes more sense.