Some months ago, Amazon Web Services changed the way they measure CPU capacity on their EC2 compute platform. In addition to the old ECUs, there is a new unit to measure compute capacity: vCPUs. The instance type page defines a vCPU as “a hyperthreaded core for M3, C3, R3, HS1, G2, and I2.” The description seems a bit confusing: is it a dedicated CPU core (which has two hyperthreads in the E5-2670