4 ms·

It reminds me of virtualization. An emulated CPU in a hypervisor will never perform as well as the physical CPU that is hosting it.

• dekhn 3y ago
  virtualization doesn't emulate a CPU; instructions typically run natively. IO is trapped and handled exceptionally.
  • kazinator 3y ago
    Hardware virtualization can still emulate peripherals. If your virtual machine thinks it has an ethernet card that doesn't actually exist, it may be nice and fast for CPU operations, but networking will take a hit.
  • ChatGTP 3y ago
    They're talking about an "emulated CPU"...
• User23 3y ago
  That's not true. Some machines are faster for some workloads when virtualizing. This has been known for decades. I recall first reading about it around 20 years ago, but I can't find the reference I'm thinking of. Nevertheless you'll find plenty of hits for faster in virtualization if you search.
• vidarh 3y ago
  A cycle exact and semantically precise one, sure. One that is allowed to prune unobserved results, on the other hand could potentially just lazily evaluate or simulate approximate outcomes and skip whole chunks of the simulation. To make claims about the computational power needed to simulate something, we really need to first know at what level of precision, and whether there are e.g. any observable effects of taking shortcuts or not (e.g. if "outside time" are not observable "inside", then skipping anything that can be lazily evaluated only if actually referenced from something observable even if it makes computation slow might be fine)