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Subject: Re: [OMPI users] Sending large boradcasts
From: Gustavo Correa (gus_at_[hidden])
Date: 2011-01-03 16:58:14


Hi Brock

He's probably hitting the MPI address boundary of 2GB.

A workaround is to declare a user defined type (MPI_TYPE_CONTIGUOUS,
or MPI_TYPE_VECTOR), to bundle a bunch of primitive data (e.g. reals),
then send (broadcast for him/her) a smaller number of those types.

See this thread:
http://www.open-mpi.org/community/lists/users/2010/11/14792.php
http://www.open-mpi.org/community/lists/users/2010/11/14816.php

I hope this helps,
Gus Correa

On Jan 3, 2011, at 11:47 AM, Brock Palen wrote:

> I have a user who reports that sending a broadcast of
>
> 540*1080 of reals (just over 2GB) fails with this:
>
>
> *** An error occurred in MPI_Bcast
> *** on communicator MPI_COMM_WORLD
> *** MPI_ERR_TRUNCATE: message truncated
> *** MPI_ERRORS_ARE_FATAL (your MPI job will now abort)
>
> I was reading the archives and there appears to be an issue with large messages. I was a little confused, is there a way to send messages larger than 2GB?
>
> The user has access to some IB machines, per a note in the archives there was an issue with writev() would this issue only be related to messages over ethernet?
>
> Thanks just trying to get some clarification.
>
> Brock Palen
> www.umich.edu/~brockp
> Center for Advanced Computing
> brockp_at_[hidden]
> (734)936-1985
>
>
>
>
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