3 ms·

I think it's more correct to say that a single core has two "sets of registers" (and I guess instruction decoders/dispatchers perhaps)... so it's a single core

• dragontamer 6y ago
  Skylake has 180 registers. "mov rax, [blah]" performs "rax = malloc()" from this pool of 180-registers / "the register file". Eventually, the retirement unit "garbage collects" the registers that aren't used anymore for recycling. Yeah, out-of-order processors are weird. (https://en.wikipedia.org/wiki/Tomasulo_algorithm https://en.wikipedia.org/wiki/Tomasulo_algorithm) If you have one thread that doesn't need a lot of registers for some reason (ie: most of its dependency chains are short, and it has very few memory operations), then you can have a 2nd thread eat up the ~180 registers that it wasn't using. "Sharing" the malloc pool of registers.