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Subject: Re: [OMPI users] MPI_Bcast not broadcast to all processes
From: Jeff Squyres (jsquyres_at_[hidden])
Date: 2007-12-05 08:41:19


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