[dekhn]

An important secret in HPC is that MPI is rarely required to achieve your objectives. In many ways, vendors just use MPI as a way to sell expensive systems. If you can find any way to make your system scale using threads on a single machine, or use non-latency-sensitive networking, do so.

[stonogo]

If you don't need a high-speed interconnect, you don't need HPC. That's not to say that MPI per se must always be involved, but if for instance the 10gbit connection on Amazon's half-baked "HPC" offering is sufficient, then you definitely don't need a supercomputer.

There is a ton of important scientific work waiting for core hours that really shouldn't be. A loosely-connected grid of laptops would serve a lot of projects very well. On the other hand, there is a large body of work that does require a classical supercomputer, so it doesn't really do anyone any good to accuse MPI of being a sales gimmick.

[dekhn]

There is plenty of HPC that does not need interconnect. It's false, categorically, to say that HPC requires interconnect of any kind.

An isolated, off-net computer - even a desktop PC- stuffed to the gills with GPUs can do HPC. On the other hand, machines connected with 10gbit might do HPC, but you'll have trouble getting codes to scale in a way that is "high performance", relative to what you can get out of threading on a single machine, or a small number of GPUs.

Very little work truly requires classic supercomputers or MPI- there are very few codes where an important engineering problem must be run on a system with low latency, high bandwidth.

[apathy]

Or rent a bigger AWS/EC2 instance to prepare for the eventual demise of old school HPC