Re:Downfall Attacks
by BeeOnRope on Tuesday August 08, 2023 @03:42PM
(#37054462)
> These are not the same thing. Afaik, most “vCPU” are hyperthreads, not physical cores.
OP didn't say otherwise. They are saying that public clouds do not let work from different tenants run on the _same_ physical core (on _different_ hyperthreads).
This doesn't prevent you from selling 1 hyperthread as 1 vCPU, it just means there are some scheduling restrictions and your smallest instance type will probably have 2 vCPUs if you have SMT-2 hardware (and that's exactly what you see on AWS outside of the burstable instance types).
OP didn't say otherwise. They are saying that public clouds do not let work from different tenants run on the _same_ physical core (on _different_ hyperthreads).
This doesn't prevent you from selling 1 hyperthread as 1 vCPU, it just means there are some scheduling restrictions and your smallest instance type will probably have 2 vCPUs if you have SMT-2 hardware (and that's exactly what you see on AWS outside of the burstable instance types).