Regardless of how tight the seastar per-hop latency is,
IB has 2.5x the per-hop fanout (2or 3 outgoing 9.6 GB links
versus 18 outgoing 4 GB/s links). higher radix means an
advantage that increases with size.
Doesn't this assume worst case all-to-all type communication
patterns.
I'm assuming random point-to-point communication, actually.
If you are just trading ghost cell data with your neighbors
and you have placed your job smartly on the torus the fan out
advantage mentioned is irrelevant. No?
if your comms are nearest-neighbor,
then yes, a nearest-neighbor fabric is your friend ;)
how often does that actually happen? to work out so neatly would
preclude, for instance, adaptive meshes, right? it seems like mostly
I see jobs with no obvious regular structure to their communication.
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