On Wed, Jan 1, 2014 at 4:34 PM, Pavan Balaji <[email protected]> wrote:

On Jan 1, 2014, at 4:09 PM, Jeff Hammond <[email protected]> wrote:

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3. Doing an extra ssh to all the nodes is expensive to do every time.

You just need a ring to verify homogeneity. Forming a ring is O(1) per node.

What is this ring you keep referring to? There’s no ring in hydra. Setting one up will lead to more trouble than be useful, with inter-proxy connections and such. I bet that’ll create more queries on this mailing list than help.

A ring is the minimum spanning topology required to verify homogeneity. Feel free to use something less efficient if that's already available in Hydra. I assume that Hydra proves each process the ability to communicate with _at least_ one process outside its node and that the connections it has the ability to establish have the ability to connect all nodes, otherwise MPI_Init wouldn't be possible. My fundamental conviction is that Hydra could verify homogeneity by exchanging and comparing a magic value created by the hash on the set independent datatype sizes at negligible overhead compared to whatever bootstrap it does already. Jeff -- Jeff Hammond [email protected]