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Subject: Re: [OMPI users] alltoall messages > 2^26
From: David Zhang (solarbikedz_at_[hidden])
Date: 2011-04-04 22:17:10


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
<mdidomenico4_at_[hidden]>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