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Subject: Re: [OMPI users] COMM_ACCEPT/COMM_CONNECT: what BTL will the connected processes use?
From: Katz, Jacob (jacob.katz_at_[hidden])
Date: 2009-04-21 12:14:59


So, sm will never be chosen in this case in the current implementation, correct?
Is there an API or another method to find out what BTL is currently used (either inside the application code or externally)?

Thanks.
--------------------------------
Jacob M. Katz | jacob.katz_at_[hidden] | Work: +972-4-865-5726 | iNet: (8)-465-5726

-----Original Message-----
From: users-bounces_at_[hidden] [mailto:users-bounces_at_[hidden]] On Behalf Of George Bosilca
Sent: Tuesday, April 21, 2009 17:48
To: Open MPI Users
Subject: Re: [OMPI users] COMM_ACCEPT/COMM_CONNECT: what BTL will the connected processes use?

With few exceptions, Open MPI will choose the best BTL. There are two
exceptions I know about:
1. sm - we didn't figure out a clean way to do it, nor we spent too
much time trying to
2. elan - the initialization of the device is a global operation, and
we cannot guarantee that all nodes are involved in the accept/connect.

   george.

On Apr 21, 2009, at 09:28 , Katz, Jacob wrote:

> Hi,
>
> In a dynamically connected client/server-style application, where
> the server uses MPI_OPEN_PORT/MPI_COMM_ACCEPT and the client uses
> MPI_COMM_CONNECT, what will be the communication method (BTL) chosen
> by OMPI? Will the communication thru the resultant inter-
> communicator use TCP, or will OMPI choose the best possible method
> (e.g. sm if the client and the server are on the same node)?
>
> Thanks.
> --------------------------------
> Jacob M. Katz | jacob.katz_at_[hidden] | Work: +972-4-865-5726 | iNet:
> (8)-465-5726
>
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