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Subject: Re: [OMPI users] MPI_Bcast not broadcast to all processes
From: alireza ghahremanian (mat2ag_at_[hidden])
Date: 2007-12-07 06:57:59


Dear Jeff

I want to send an integer vector of size 4000.It is a
very confusing problem.

--- Jeff Squyres <jsquyres_at_[hidden]> wrote:

> If you're seeing the same error from 2 entirely
> different MPI
> implementations, it is possible that it is an error
> in your code.
>
> Ensure that all processes are calling MPI_Bcast with
> the same
> arguments (e.g., count, datatype, root, etc.), even
> on that 4000th
> iteration.
>
> How big are the blocks that you are sending around?
>
>
> On Dec 5, 2007, at 4:08 AM, alireza ghahremanian
> wrote:
>
> > Dear Friends,
> >
> > I am writing a matrix multiplication program with
> MPI. MPI_Bcast does
> > not broadcast to all processes, in last iteration
> for block size
> > greater than a specific size. I test it with both
> MPICH and OPENMPI.I
> > have 12 processes which 7 of them are reached to
> MPI_Bcast but when
> > master (rank 0) send only 6 of them receive the
> broadcast (exactly
> > from
> > rank 1 to 6) and rank 7 stays in waiting.
> Surprisingly this happen
> > only
> > in iteration 3999 from 4000 and in the rest of
> cases every thing is
> > all
> > right, also if I reduce the block size, which,
> will be sent, every
> > thing will be done correctly.
> >
> >
> >
> >
> >
>
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>
> --
> Jeff Squyres
> Cisco Systems
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