KUBERNETES - How Millicores For CPU Is Calculated In Kubernetes?

It's best to see millicores as a way to express fractions, x millicores correspond to the fraction x/1000 (e.g. 250millicores = 250/1000 = 1/4).

The value 1 represent the complete usage of 1 core (or hardware thread if hyperthreading or any other SMT is enabled).

So 100mcpu means the process is using 1/10th of a single CPU time. This means that it is using 1 second out of 10, or 100ms out of a second or 10us out of 100.