The virtual server that I've been renting from Linode for several years has up until today, been using User Mode Linux (UML) for machine virtualization. Linode recently launched a beta testing program for a new Xen virtual hosting system. I signed up this evening and migrated my server over to the new Xen host. The migration went flawlessly - many kudos to Chris and the rest of the linode team. After the migration, my server booted up perfectly and almost instantly, I could feel the affects of the increased performance that Xen gives. Previously, while running on UML, there always seemed to be a bit of lag. Nothing huge, but from time to time, I could tell I was running in a virtual machine. Not any more - this thing is wicked fast. Best of all, Xen allows SMP guests, so my lowly virtual server now has 4 processors at its disposal. This is very, very cool. We'll see how performance holds up once more guests are migrated to this machine, but I'm optimistic that things will continue to be quite snappy.
Here's a screenshot of me compiling a new version of openssh. Note the
four happy CPU graphs at the top of the screen. They make me happy :-)