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Subject: Re: [OMPI users] Any scientific application heavily using MPI_Barrier?
From: Durga Choudhury (dpchoudh_at_[hidden])
Date: 2009-03-05 11:01:22


I would perhaps remember your statement like part of a religious scripture!

Request to you and everyone else: if you know of a good book and/or
online tutorial on 'how to write large parallel scientific programs',
I am sure it would be of immense use to everyone in this list.

Best regards


On Thu, Mar 5, 2009 at 10:25 AM, Jeff Squyres <jsquyres_at_[hidden]> wrote:
> On Mar 5, 2009, at 9:29 AM, Shanyuan Gao wrote:
>> I am doing some research on MPI barrier operations.  And I am ready
>> to do some performance test.
>> I wonder if there are any applications that using barriers a lot.
>> Please let me know if there
>> is any.  Any comments are welcomed.  Thanks!
> I don't remember who originally said it, but I've repeated the statement:
> any MPI program that relies on a barrier for correctness is an incorrect MPI
> application.
> There's anecdotal evidence that throwing in a barrier every once in a while
> can help reduce unexpected messages (and other things), and therefore
> improve performance a bit.  But that's very application dependent, and
> usually not frequent.
> Why do you want to do a barrier?  Particularly one that sounds like it might
> be in your critical performance path?
> --
> Jeff Squyres
> Cisco Systems
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