Server Update April 2013: Positioning the HP Moonshot 1500

Estimating S1260 Server Performance

As the Atom S1260 is very similar to the Atom N2800, we went one step further. We tested the 32 nm Atom in a real workload, the same workload that we used in our review of the Calxeda based Boston Viridis server.

It is simple: even at 2GHz, the Atom S1260 is no match for Calxeda's EnergyCore at 1.4GHz. The EnergyCore is the better server chip thanks to out of order execution, a 4 times larger L2-cache (4 MB) and the fact that it can offer 4 real cores.  Even if we assume that the 2GHz Atom S1260 performs 8% better thanks to its higher clockspeed, it is no match for Calxeda's EnergyCore. 

So let us summarize. The current A9 based Calxeda EC 1.4GHz is about 40% faster and consumes half the power of the Atom S1260. Therefore it is not unreasonable to assume that the performance per Watt ratio of the Calxeda SoC will be up to 3 times better. 

There are more indications that our assumptions are not far off. We quote the white paper at HP's site (page 5): 

"A completely populated system will be in the ~850W ballpark. That system powers 180 x 2.0GHz threads, with 2GB of RAM for each thread, at under 5W per thread."

That means that each cartridge needs about 19 W. Let us assume that 4 W is taken by the disk. That is generous as in most webserving workloads, the disk will be hardly active. That means that one server node needs about 15 W. Compare this with a measured 8.3W per Calxeda server node and you'll understand that there is little doubt in our minds that the S1260 is nowhere near the performance/watt of the ARM alternative.