I don't think it's as simple as saying "Rackspace is better bang for buck in CPU terms". This is a complicated area and one which is being researched at universities. See [1] for one such research project, which mentions that there is even a "reasonable extent of variation amongst instances from the same providers". It's also application specific and hard to predict (who knows what other VMs will be running on the same physical box as your VM in the future).
Our blog post was a first step in this sort of comparison, where we wanted to see if there was a significant-enough difference between providers to warrant further studies.
Also, see asharp's comment above about Rackspace using a credit scheduler with burst capacity.
Our blog post was a first step in this sort of comparison, where we wanted to see if there was a significant-enough difference between providers to warrant further studies.
Also, see asharp's comment above about Rackspace using a credit scheduler with burst capacity.
[1] Lee Gillam, Bin Li, John O.Loughlin and Anuz Pranap Singh Tomar (2012) "Fair Benchmarking for Cloud Computing Systems". http://www.cs.surrey.ac.uk/BIMA/People/L.Gillam/downloads/pu...