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Subject: Re: [OMPI users] COMM_ACCEPT/COMM_CONNECT: what BTL will the connected processes use?
From: George Bosilca (bosilca_at_[hidden])
Date: 2009-04-21 14:58:05


No, we do not expose such kind of information to the upper layer. If
you really want I can tell you how to do it in a dirty way, but only
if you really need to know...

   george.

On Apr 21, 2009, at 12:14 , Katz, Jacob wrote:

> 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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