Hi. I'm the author of that presentation, and I just got a text message from a friend saying that I'm on the front page of Hacker News...

The one thing in that talk that I was never 100% sure of was whether it was block-mq that provided the performance improvement. It wasn't until about a year later that I came across some articles which confirmed that that it was actually due to the development of, and subsequent fixes to, the Xen persistent-grants feature.

In other words, ignore slides 15 and 16. =/