1 vcore instance is using 100% of node's CPU
I have a default set up as per this document: http://docs.openstack.org/trunk/install-guide/install/apt/content/
So I have a controller node and a compute node. The compute node has an 8-core AMD processor and 16GB of RAM. I created an instance on it with 2GB of ram and 1 vcore (flavor:small). Now here is what's peculiar - when I run a processor intensive operation on the instance, say John The Ripper, the whole compute node is utilizing 100% of CPU.
Why does that happen? Why doesn't the instance stay within the confines of the resources I allocate to it?