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Subject: Re: [OMPI users] [Beowulf] How to justify the use MPI codes on multicore systems/PCs?
From: Durga Choudhury (dpchoudh_at_[hidden])
Date: 2011-12-12 11:40:00


I think this is a *great* topic for discussion, so let me throw some
fuel to the fire: the mechanism described in the blog (that makes
perfect sense) is fine for (N)UMA shared memory architectures. But
will it work for asymmetric architectures such as the Cell BE or
discrete GPUs where the data between the compute nodes have to be
explicitly DMA'd in? Is there a middleware layer that makes it
transparent to the upper layer software?

Best regards
Durga

On Mon, Dec 12, 2011 at 11:00 AM, Rayson Ho <raysonlogin_at_[hidden]> wrote:
> On Sat, Dec 10, 2011 at 3:21 PM, amjad ali <amjad11_at_[hidden]> wrote:
>> (2) The latest MPI implementations are intelligent enough that they use some
>> efficient mechanism while executing MPI based codes on shared memory
>> (multicore) machines.  (please tell me any reference to quote this fact).
>
> Not an academic paper, but from a real MPI library developer/architect:
>
> http://blogs.cisco.com/performance/shared-memory-as-an-mpi-transport/
> http://blogs.cisco.com/performance/shared-memory-as-an-mpi-transport-part-2/
>
> Open MPI is used by Japan's K computer (current #1 TOP 500 computer)
> and LANL's RoadRunner (#1 Jun 08 – Nov 09), and "10^16 Flops Can't Be
> Wrong" and "10^15 Flops Can't Be Wrong":
>
> http://www.open-mpi.org/papers/sc-2008/jsquyres-cisco-booth-talk-2up.pdf
>
> Rayson
>
> =================================
> Grid Engine / Open Grid Scheduler
> http://gridscheduler.sourceforge.net/
>
> Scalable Grid Engine Support Program
> http://www.scalablelogic.com/
>
>
>>
>>
>> Please help me in formally justifying this and comment/modify above two
>> justifications. Better if I you can suggent me to quote some reference of
>> any suitable publication in this regard.
>>
>> best regards,
>> Amjad Ali
>>
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>
>
>
> --
> Rayson
>
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