On 2022-02-10, Mihai Popescu <mih...@gmail.com> wrote: > I see in the AMD spec that I have a 4 core CPU, no *-threading. So it > is 4 core, 4 threads, no multi, simultaneous, hyper, etc. > Still the sysctl hw.ncpuonline reports 2, but it found 4 and top > displays CPU0 and CPU2 only ( that is 2). I am aware that each pair of > cores is using a shared FPU. > > My question is, how many CPU cores is using OpenBSD from that CPU?
2, because that's what is reported in hw.ncpuonline. And the reason it is 2, is because the hardware is replying to the CPUID instruction that two of the "cpu"s are actually smt rather than full cpus, and because hw.smt is at the default. It's possible that AMD made the decision to answer that way based on the shared FPU, I don't know.
