>Runs fine on commodity clusters.

Kind of.... For simple, low communication jobs this is true. But when you start trying to find the eigenvectors of a large sparse matrix, communication becomes your bottleneck, at which point MPI on commodity clusters (those without a really fancy interconnect) "works", but not fast enough to be useful.

I don't think "really fancy interconnects" makes a cluster not commodity, since the original post in this thread is about supercomputer processors. You can put Infiniband in any system with a PCI-e 3.0 bus.

Communication would become a bottleneck regardless of whether you're using MPI or something else. The problem you're talking about has nothing to do with MPI; it is intrinsic to distributed computing itself.

And what system on commodity clusters is fast enough in this case?

What would you define as a "commodity cluster"? To me it's a 512-core vendor-specific blade server with special interfaces to get more bandwith at lower latency across longer links. But maybe i'm just an old fogey.

blades were never more than a marketing trick: the offer nothing that can't be achieved in a standard chassis. there were a few multi-chassis SMP/NUMA machines that had cache coherency over external interfaces, but that was neither commodity nor HPC.

1) Not vendor specific 2) Not blades 3) 10Gbe, not special interfaces

That is a commodity cluster.

Did you fucking read TFA?

It's title literally is: "HPC is dying, and MPI is killing it".

His comment shows more understanding of the article's main point (about the demise of HPC) that your "it's about MPI"...