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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
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