Server Fault is a question and answer site for system and network administrators. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I just have a quick question regarding EC2. Its to do with CPU sharing on Amazon EC2. Amazon supports a number of different instance types, be it small, medium, large etc. Each of these has a number of virtual cores assigned to them. My question is this, if the physical host has for instance 8 cores and I instantiate an m1.small instance which has 1 virtual cpu, what happens when I request CPU cycles? Are the CPU cycles being taken off multiple physical cores (i.e. across all 8 if any are idle) or is there a dedicated single physical core that is assigned to my VM.


share|improve this question

The former option - from any available free core - that's the default for any hypervisor although most will allow you to 'peg' a VM to a specific core if there's a good reason for doing so.

share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.