You mention that, "finally, both the hypervisors and the guests run finely-tuned, bare-metal OSes, with only what’s needed, and nothing more." I'm curious what bare-metal OS do you use?
The OS is exherbo (http://exherbo.org), a source-based distribution.
The kernels are tuned for virtualization and the system is overall very light.
Okay cool thanks for sharing I'll check it out.
Congrats on adding Docker support. Looking forward to trying it out.