Extensive Benchmarks Of Amazon's EC2 Compute Cloud Performance
phoronix.com
phoronix.com
All I can get from these is that Amazon isn't lying that their instance sizes are different in terms of compute units and memory.
According to the specs Amazon gives us, "High-Memory" instances have 3.25 Compute Units per virtual core, while "High-CPU" only 2.5. It would be interesting to know what is going on: are their compilation tests unable to properly utilize many cores, or the nodes assigned to "High-Memory" instances tend to have more powerful hardware, or what?
For all the dollars being thrown at EC2, I'm surprised someone hasn't gone nuts with benchmarking this for the authority, notoriety and seo link juice.
http://amistrongeryet.com/dashboard.jsp
This covers a variety of AWS operations, ranging from simple EC2 CPU benchmarks to SimpleDB and RDS operations. I also include some measurements of Google App Engine. I've put a lot of focus on measuring variation over time, and measuring outliers (i.e. 99.9th percentile, not just mean). I'd like to measure variation across instances, but haven't gotten around to it.
The web site linked above has no documentation at the moment, and is a bit broken in other ways, but the data may be of interest. I have a little blog (http://amistrongeryet.blogspot.com/) where I've discussed some of my findings, e.g. http://amistrongeryet.blogspot.com/2010/04/early-results-on-..., http://amistrongeryet.blogspot.com/2010/04/beginnings-of-rob..., and http://amistrongeryet.blogspot.com/2010/04/cloud-data-storag....
If there's interest, I'll put a little effort into cleaning up and documenting the data reporting site.