I was thinking about machines with a shared memory bus (I'm 90% sure that's the right term) so yeah not things in the Top500. I'm thinking about your standard 6

I was thinking about machines with a shared memory bus (I'm 90% sure that's the right term) so yeah not things in the Top500. I'm thinking about your standard 64-core servers. I know that in the large MPI is best because getting that many cores to use the same memory bus just isn't feasible. Sorry for the confusion, I didn't read your comment carefully.