It was asked during the community concall whether the below may be related to ticket #2722


On 04/04/2011 10:17 PM, David Zhang wrote:
Any error messages?  Maybe the nodes ran out of memory?  I know MPI implement some kind of buffering under the hood, so even though you're sending array's over 2^26 in size, it may require more than that for MPI to actually send it.

On Mon, Apr 4, 2011 at 2:16 PM, Michael Di Domenico <> wrote:
Has anyone seen an issue where OpenMPI/Infiniband hangs when sending
messages over 2^26 in size?

For a reason i have not determined just yet machines on my cluster
(OpenMPI v1.5 and Qlogic Stack/QDR IB Adapters) is failing to send
array's over 2^26 in size via the AllToAll collective. (user code)

Further testing seems to indicate that an MPI message over 2^26 fails
(tested with IMB-MPI)

Running the same test on a different older IB connected cluster seems
to work, which would seem to indicate a problem with the infiniband
drivers of some sort rather then openmpi (but i'm not sure).

Any thoughts, directions, or tests?
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David Zhang
University of California, San Diego
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