To test this out, I created a low-end, 512MB machine at both Joyent and Rackspace. Joyent charges 3 cents per hour for such a machine, while Rackspace charges 2.2 cents. I ran a number of DaCapo benchmarks for Java. The SmartOS came with Java 1.6 already installed. I had to install OpenJDK 1.6 on the CentOS box I built at Rackspace.
Most of the benchmarks ran between two and three times faster on the Joyent box. Some that used a heavy amount of IO -- such as the luindex benchmark that builds a Lucene index -- ran slightly more than three times faster. The avrora benchmark that simulates microcontrollers ran at about the same speed on both servers.
At the beginning, the Joyent box was often slower than the Rackspace box on the multithreaded benchmarks because it created 24 threads. Why? SmartOS poked around in the machine and decided it could run 24 threads because it was running on a 24-processor machine. When I limited the benchmark to one thread, the Joyent machine sped up dramatically (see table below). Even for the multithreaded tests, the Linux-based Rackspace machine automatically chose one thread.
These results show that for all of the talk about commodity servers, there are plenty of differences between the off-the-shelf machines. It pays to spend some time testing your particular application, then tuning it -- the operating system, the level of disk access, and the level of network access can affect the speeds dramatically. What may be good for one application may not benefit another.
Fast ride in a Web machineJoyent is not relying on SmartOS alone. The company also offers pre-loaded "appliances." When you click through the options for your brand-new box, you'll see a number of machines that come ready to run packages such as Node.js, Percona, Riak, and MongoDB. You push the button and get a machine with all of the files in the right places, so you can start running the services immediately. These can certainly save you time starting up, but they're not as simple as they could be. After you push the start button for a Node box, for instance, you still get to log in and do everything with the command line.
You don't need to run Node.js and SmartOS to want to use Joyent. Joyent Cloud offers all the standard distros at prices that seem, on the face, to be 15 to 25% cheaper than Amazon Web Services. On paper, at least, the machines appear to be basically the same with equivalent specs.