Energy and HPC
AVX/FP intensive applications are known to be real power hogs. How bad can it get? We used the OpenFOAM test and measured both average and maximum power (the 95th percentile). Average power tells us how much energy will be consumed for each HPC job while maximum power is important as you have to allocate enough amps to your rack to feed your HPC server/cluster.
This confirms there is more going on than just the fact that our "Wildcat Pass" server consumes more than the Supermicro server in this test. At peak, the Xeon E5-2699 v3 consumes almost 450W (!!) more than at idle. Even if we assume that the fans take 100W, that means that 350W is going to the CPUs. That's around 175W per socket, and even though it's measured at the wall and thus includes the Voltager regulators, that's a lot of power. The Xeon E5-2699 v3 is a massive powerhouse, but it's one that needs a lot of amps to perform its job.
Interestingly, the Xeon E5-2695 v3 is also using more power than all previous Xeons. The contrast with our Drupal power measurements is very telling. In the Drupal test, the CPU was able to let many of the cores sleep a lot of the time. In OpenFOAM, all the cores are working at full bore and the superior power savings of the Haswell cores deep sleep states do not matter much. But which CPU is the winner? To make this more clear, we have to calculate the actual energy consumed (average power x time ran).
When we look at how much energy is consumed to get the job done, the picture changes. The old Xeon "Sandy Bridge EP" is far behind. It is clear that Intel has improved AVX efficiency quite a bit. The low power Xeon E5-2650L v3 is a clear winner. In second place, the fastest Xeon on the planet actually saves energy compared to the older Xeons, as long as you can provide the peak amps.
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