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Subject: Re: [OMPI users] do all processors have to execute MPI_Bcast?
From: Anton Shterenlikht (mexas_at_[hidden])
Date: 2010-07-17 08:09:25

On Sat, Jul 17, 2010 at 07:49:21AM -0400, Jeff Squyres wrote:
> On Jul 17, 2010, at 4:13 AM, Anton Shterenlikht wrote:
> > Sorry, just to be absolutely clear, are you saying
> > that even though only one process in the communicator
> > is calling Bcast, the call will be made on all
> > processes?
> MPI does not magically cause all processes to call MPI_Bcast behind the scenes for you. You must ensure that every process in the communicator explicitly invokes MPI_Bcast. You can do whatever logic you want (to include "if" blocks, etc.) as long as they all call MPI_Bcast.
> To be clear: all MPI collective operations must be explicitly invoked by every process in the target communicator.

Jeff, many thanks. Now I'm very clear indeed.

Anton Shterenlikht
Room 2.6, Queen's Building
Mech Eng Dept
Bristol University
University Walk, Bristol BS8 1TR, UK
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