Open MPI User's Mailing List Archives

Subject: Re: [OMPI users] Does MPI_Bsend always use the buffer?
From: George Bosilca (bosilca_at_[hidden])
Date: 2007-12-11 10:50:03

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On Dec 11, 2007, at 10:33 AM, Gleb Natapov wrote:

> On Tue, Dec 11, 2007 at 10:27:32AM -0500, Bradley, Peter C. (MIS/
> CFD) wrote:
>> In OpenMPI, does MPI_Bsend always copy the message to the user-
>> specified
>> buffer, or will it avoid the copy in situations where it knows the
>> send can
>> complete?
> If the message size if smaller than eager limit Open MPI will not use
> user-specified buffer for it.

This is an implementation details. You should avoid relying on such
things in a portable MPI applications. The safe assumption here is
that MPI_Bsend always copy the buffer, as described in the MPI standard.

   george.

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