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Subject: Re: [OMPI users] Problem with MPI_Intercomm_create
From: Jeff Squyres (jsquyres_at_[hidden])
Date: 2011-06-07 09:00:08

George --

Do we need to file a bug about this?

On Jun 7, 2011, at 1:57 AM, George Bosilca wrote:

> Frederic,
> Attached you will find an example that is supposed to work. The main difference with your code is on T3, T4 where you have inversed the local and remote comm. As depicted on the picture attached below, during the 3th step you will create the intercomm between ab and c (no overlap) using ac as a bridge communicator (here the two roots, a and c, can exchange messages).
> Based on the MPI 2.2 standard, especially on the paragraph in PS:, the attached code should have been working. Unfortunately, I couldn't run it successfully neither with Open MPI trunk nor MPICH2 1.4rc1.
> george.
> PS: Here is what the MPI standard states about the MPI_Intercomm_create:
>> The function MPI_INTERCOMM_CREATE can be used to create an inter-communicator from two existing intra-communicators, in the following situation: At least one selected member from each group (the “group leader”) has the ability to communicate with the selected member from the other group; that is, a “peer” communicator exists to which both leaders belong, and each leader knows the rank of the other leader in this peer communicator. Furthermore, members of each group know the rank of their leader.
> <intercomm_create.c><Mail Attachment.txt><PastedGraphic-2.pdf><Mail Attachment.txt><Mail Attachment.txt>

Jeff Squyres
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