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Subject: Re: [OMPI devel] Threading
From: Kenneth Lloyd (kenneth.lloyd_at_[hidden])
Date: 2010-10-12 11:13:25


Ugly is in the eye of the beholder. Some might even think it elegant.

-----Original Message-----
From: devel-bounces_at_[hidden] [mailto:devel-bounces_at_[hidden]] On
Behalf Of Ralph Castain
Sent: Tuesday, October 12, 2010 9:01 AM
To: Open MPI Developers
Subject: Re: [OMPI devel] Threading

Hmmm...I don't understand what you just said, but it definitely sounds
-ugly-! :-)

I'll take your word for it - we may have to provide a lower performance
version for such oddball purposes, and offer a higher capability version for
everyone else. I'll see if I can keep a single version, though, assuming the
code doesn't get too convoluted so as to become unmaintainable.

Otherwise, I'll branch it and "freeze" a non-threaded version for the
unusual case.

Thanks!

On Oct 12, 2010, at 8:51 AM, Kenneth Lloyd wrote:

> In certain hybrid, heterogeneous HPC configurations, mpirun often cannot
or
> should not be threaded through the OS under which OpenMPI runs. The
primary
> OS and MPI can configure management nodes and topologies (even other MPI
> layers) that subsequently spawn various OSes and other lightweight
kernels.
> These share memory spaces and indirectly access the program stacks in
> various devices.
>
> In short, yes, there are environments where this would cause a problem.
>
> ==================
> Kenneth A. Lloyd
> Watt Systems Technologies Inc.
>
>
> -----Original Message-----
> From: devel-bounces_at_[hidden] [mailto:devel-bounces_at_[hidden]] On
> Behalf Of Barrett, Brian W
> Sent: Tuesday, October 12, 2010 8:24 AM
> To: Open MPI Developers
> Subject: Re: [OMPI devel] Threading
>
> On Oct 11, 2010, at 11:41 PM, Ralph Castain wrote:
>
>> Does anyone know of a reason why mpirun can -not- be threaded, assuming
> that all threads block and do not continuously chew cpu? Is there an
> environment where this would cause a problem?
>
> We don't have any machines at Sandia where I could see this being a
problem.
>
> Brian
>
> --
> Brian W. Barrett
> Dept. 1423: Scalable System Software
> Sandia National Laboratories
>
>
>
>
>
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