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Subject: Re: [OMPI devel] Using ompi_proc_t's proc_name.vpid as Universal rank
From: Sajjad Tabib (stabib_at_[hidden])
Date: 2007-11-30 16:41:27


Thanks for the clarification. So, now I am wondering how rank information
regarding processes in MPI_COMM_WORLD are assigned. Is there a table that
stores unique integer values for processess or is rank assignment done in
some other manner?


Sajjad Tabib

Tim Prins <tprins_at_[hidden]>
Sent by: devel-bounces_at_[hidden]
11/30/07 07:22 AM
Please respond to
Open MPI Developers <devel_at_[hidden]>

Open MPI Developers <devel_at_[hidden]>

Re: [OMPI devel] Using ompi_proc_t's proc_name.vpid as Universal rank

Hi Sajjad,

The vpid is not unique. If you do a comm_spawn then the newly launched
processes will have a new jobid, and their vpids will start at 0. So the
whole process name is unique.

However, there is talk now of being able to join 2 jobs that were
started completely independently. This may lead to the point where a
process name is no longer unique, however this work appears to be a ways
out and as far as I know no decisions have been made on it yet.

Hope this helps,


Sajjad Tabib wrote:
> Hello,
> I have a proprietary transport/messaging layer that sits below an MTL
> component. This transport layer requires OpenMPI to assign it a rank
> that is unique and specific to that process and will not change from
> execution to termination. In a way, I am trying to find a one-one
> correspondence between a process's universal rank in OpenMPI and this
> transport layer. I began looking at ompi_proc_t from different processes

> and seemingly found a unique identifier, proc_name.vpid. Consequently, I

> assigned the ranks to each process in my transport layer based on the
> value of the local vpid of each process.
> I have not tested this thoroughly, but it has been working so far.
> Although, I would like to make sure that this is a good approach, or
> know, at least, whether if there are other ways to do this. I would
> appreciate it if you could leave me feedback or give suggestions on how
> to assign universal ranks to a proprietary transport software.
> Thanks for your help,
> Sajjad Tabib
> ------------------------------------------------------------------------
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> devel mailing list
> devel_at_[hidden]

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