Re: [Boost-users] mpi non-blocking communication

Subject: Re: [Boost-users] mpi non-blocking communication
From: Hicham Mouline (hicham_at_[hidden])
Date: 2010-12-07 03:37:49

> -----Original Message-----
> From: boost-users-bounces_at_[hidden] [mailto:boost-users-
> bounces_at_[hidden]] On Behalf Of Riccardo Murri
> Sent: 07 December 2010 08:14
> To: boost-users_at_[hidden]
> Subject: Re: [Boost-users] mpi non-blocking communication
> 
> Hi Hicham,
> 
> On Tue, Dec 7, 2010 at 12:10 AM, Hicham Mouline <hicham_at_[hidden]>
> wrote:
> > On a related note, I posted a question to the openmpi forum.
> > MPI_INIT is identical MPI_INIT_THREAD(MPI_THREAD_SINGLE),
> > but I couldn't see the utility of having MPI_THREAD_FUNNELED.
> >
> 
> MPI_THREAD_SINGLE = no threads at all.
> 
> MPI_THREAD_FUNNELED = you can have threads, but only the *main* thread
> (see below) issues MPI calls; you can think of this as: your
> application is multi-threaded, but it is single-threaded when it comes
> to MPI interaction.

Thanks Riccardo,
I am just curious as to the value of distinguishing between these 2.
Is it just informative?
I mean, as you said, it is as if the application is single-threaded when it
comes to MPI interaction.

What value is there in telling the MPI implementation that we have other
threads but they will not call you?

I guess I'm stuck on this point,

regards,