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Benchmarking

Ensuring that you get non-IB nodes

You can specify gigE only nodes using a "compute-eth" flag

nodes=2:compute-eth:ppn=8

and this will only allow the code to run on "gigabit only nodes. So even if IB nodes are available it will sit in the queue.

By default (ie no property feature for the node) the scheduler (moab) is setup to use the gigE nodes first then the IB nodes. The scheduler configuration is ongoing but explicitly putting either "compute-eth" for ethernet or "ib" for infiniband nodes will guarantee the right type of node is used.

Also you can specify the type of interconnect directly on the mpirun line using mpirun --mca btl self,tcp for ethernet, so even if it was on an IB node it would still use ethernet for communication. Since the nodes are exactly the same except for the IB card, any benchmarking would still be valid.

Scott August 27 2009