HPCWire reviews a European project to develop exascale software.
Two current Paths to Exascale Hardware
There are a number of constraints of the architecture for exascale. One constraint is cost. Everybody says a machine can cost no more than $200 million. You're going to spend half your money on memory, so you have take that into consideration.
There are also other constraints that come into play. For example, the machine can consume no more than 20 MW. That's thought to be the upper limit for a reasonable machine from the standpoint of power, cooling, etc.
Currently there are two ways to exascale hardware. One is going to be lightweight processors. By lightweight, we mean things like the Blue Gene [PowerPC] processor. One general way to characterize this architecture is 1GHz in processor speed, one thousand cores per node, and one million nodes per system. A second path to exascale is commodity processors together with accelerators, such as GPUs. The software would support both those models, although there would be differences we'd have to deal with.
Both of the models generate 10^18 FLOPS and both have on the order of a billion threads of execution. We realize that represents a lot of parallel processing and we need to support that in some manner. That's today's view of the hardware, although clearly, that could change.
