I sort of hope we don't see SMT ARM cores. SMT was/is a huge pain for side channels and all the ARM chip houses dodged that one by nature of just never implementing it. I would hope that the concern of cloud vendors over isolation would be enough to discourage bringing more SMT uarchs in to this world.
Or just disabling SMT? SMT can give a good utilization boost and it feels like a shame for it not to be an option, especially since CPUs are not getting faster at the same rate they used to anymore. You can disable it on AMD and Intel x86 cores, as well as on the IBM Power ones.
Generation after generation, hyperthreads on almost every generation of Intel core have turned in mediocre to terrible benchmarks. Neither thread makes full progress , and on some versions you would see more IPC with them turned off.
AMD might have managed better, though I see benchmarks where theirs is also a wash. It doesn’t mean Arm or RISC-V will see any benefit.
I've seen around 20% increase in even dumb "a web app returning some text" benchmarks. It certainly shouldt be charged as a second real core would but it isn't nothing (like in P4 era you apparently time travelled from)
But that's entirely beside the point and I'm not sure why you try to derail the conversation into different direciton.
