5

With regard to the Apple M1 chip, I have looked around at various sites but have not seen any mention of the SMT feature more commonly know by Intel’s trademark, Hyper-Threading Technology.

I suppose one could presume there is no SMT in the M1, but I would prefer seeing a definitive statement.

1 Answer 1

10

There's no mention of SMT in Apple's documentation for M1. The closest we can get to definitive is what macOS tells us.

  • On a Mac with an Intel chip supporting Hyper-Threading Technology, Activity Monitor → Window → CPU Usage shows twice the number of vertical bars as System Information → Hardware → Total Number of Cores reports.
  • On a Mac with an M1 chip, the number of bars is the same as the number of reported cores.

Therefore we can conclude there is no hyper-threading.

screenshot of System Information → Hardware → Total Number of Cores and Activity Monitor's Window → CPU Usage window.

5
  • @Basil Bourque, Okay I'd obscure the Serial Number and UUIDs, but why obscure System Firmware Version and OS Loader Version? Aug 14, 2021 at 20:41
  • @user3439894 Why not? Aug 14, 2021 at 22:34
  • 1
    @grg Do you know which of the 8 bars are for the 'performance' and 'efficiency' cores?
    – Gilby
    Aug 14, 2021 at 22:39
  • @Gilby powermetrics -s cpu_power shows the first 4 as efficiency and the last 4 as performance, so I imagine this translates to Activity Monitor too.
    – grg
    Aug 14, 2021 at 22:42
  • @grg: I guess it makes sense to do it that way, because it allows to easily "turn the performance cores on and off" by simply reporting numCpus = 4 or 8, without having to make too many changes to the scheduling code of the OS. Heck, if the thermal management of the firmware does that automatically, you could even run an OS that doesn't even know about the different kinds of cores, and you would still get at least some of the benefits, as long as the OS supports CPU hot plugging. Aug 15, 2021 at 8:53

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .