If you eliminate the hypervisor, you don't have vCPUs at all, so I'm not sure how this is a useful comparison. The question of IPC performance is an interestin

If you eliminate the hypervisor, you don't have vCPUs at all, so I'm not sure how this is a useful comparison. The question of IPC performance is an interesting one. We've been building up a database of open source results that show wildly diverging results on different architectures. Surf through http://fable.io http://fable.io for it, or read this work in progress: http://anil.recoil.org/papers/drafts/2012-usenix-ipc-draft1.pdf http://anil.recoil.org/papers/drafts/2012-usenix-ipc-draft1.... http://anil.recoil.org/talks/fosdem-io-2012.pdf http://anil.recoil.org/talks/fosdem-io-2012.pdf (fosdem slides) The TL;DR of these numbers is that it's very hard to make firm performance hypotheses about IPC across architectures, NUMA and hypervisors.