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Subject: Re: [OMPI users] MPI_Init() and MPI_Init_thread()
From: Brian Budge (brian.budge_at_[hidden])
Date: 2010-03-03 11:59:45


I believe that it specifies the *minimum* threading model supported. If I
recall, opmi is already funnel safe even in single mode. However, if mpi
calls are made from outside the main thread, you should specify funneled for
portability

  Brian

On Mar 2, 2010 11:59 PM, "Terry Frankcombe" <terry_at_[hidden]> wrote:

I can't speak for the developers. However, I think it's to do with the
library internals.

>From here: http://www.mpi-forum.org/docs/mpi-20-html/node165.htm

"Advice to implementors.

"If provided is not MPI_THREAD_SINGLE then the MPI library should not
invoke C/ C++/Fortran library calls that are not thread safe, e.g., in
an environment where malloc is not thread safe, then malloc should not
be used by the MPI library.

"Some implementors may want to use different MPI libraries for different
levels of thread support. They can do so using dynamic linking and
selecting which library will be linked when MPI_INIT_THREAD is invoked.
If this is not possible, then optimizations for lower levels of thread
support will occur only when the level of thread support required is
specified at link time. ( End of advice to implementors.)"

On Wed, 2010-03-03 at 16:33 +0900, Yuanyuan ZHANG wrote:
> Hi all,
>
> I am a beginner of MPI an...