the problem with benchmarking a virtual instance's CPU is that how much you get varies quite a bit based on your weight and how much contention you have. If yo

the problem with benchmarking a virtual instance's CPU is that how much you get varies quite a bit based on your weight and how much contention you have. If you have a system with 512MiB ram on a box and a system with 2048Mib ram on the same box, and they each have 1 vcpu, and they are weighted appropriately, when the cpu is idle, the 512 system will have just as much cpu as the 2048MiB system. When there is contention, the weighting will step in and give the 2048MiB system more CPU, though. (of course, I believe that amazon does not mix instance sizes. Even so, assuming an even ram to cpu ratio, which is a pretty good assumption, the 2048MiB ram system on a system full of 2048MiB guests will have much better worst case performance than a 512MiB guest on a system with a similar ram/cpu ratio, even though if they both have 1 vcpu their best case performance will be about the same, assuming the cpu cores on each hardware are of similar speed.) Really, if you are going for imperial data, you should do it the way Eivind Uggedal did it. He repeatedly ran a benchmark and recorded results over a very long period of time. Doing it just once is going to get you a pretty random result, and on average, is going to make a small instance look much better (cpu wise) than it is in the worst case, and really, you usually have to design for something fairly close to the worst case.