Scott, SR-IOV enabled hardware and software allow migration. This is what the Intel link and some of the AMD documents I have seen on the web mention. This post talks about non-SR-IOV version of passthrough which does support VMotion. vSphere does not support SR-IOV yet, though we had a Tech demo in IDF'09. http://www.youtube.com/watch?v=xp3k85Y_a7g

Rick, as you say, a basic TCP_RR test or a ping test is easy to run even with the complications of interrupt coalescing. This post is narrowly focused on the benefits of DirectPath I/O for some representative enterprise workloads (for which we already have whitepapers explaining performance in virtualized environments). For these workloads, packet rate rather than latency was the biggest differentiating factor.

We have seen better latency characteristics with DirectPath I/O in some experiments (e.g., up to 20% benefit with ping). Since this is a blog post, we wanted to use benchmarks whose virtualized performance numbers were publicly available and explained in detail. Adding latency would have necessitated lot of ground work that is more suited to a whitepaper than a blog post.