Re: [OMPI users] users Digest, Vol 536, Issue 2

[Mohammad Huwaidi]

The kind of recovery I am seeking after is easy, and the following 
simple example illustrates the point:
I want to send a message to a different node.  If it does not respond to 
me, I do not want my application to crash.  I want to continue using 
other node resources.

I hate it when a node crashes that all my MPI_WORLD goes now.  Is there 
a way around that?

I could give up the other extra hairy stuff, but it would be difficult 
to lose my running job whenever a node or application goes down.

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Today's Topics:

   1. threading (Sam Adams)
   2. Re: users Digest, Vol 536, Issue 1 (Mohammad Huwaidi)
   3. Fault Tolerance (Mohammad Huwaidi)
   4. Re: Fault Tolerance (Thomas Spraggins)
   5. Re: Fault Tolerance (George Bosilca)
   6. MPI processes  swapping out (Heywood, Todd)
   7. deadlock on barrier (tim gunter)


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Message: 1
Date: Wed, 21 Mar 2007 11:29:34 -0500
From: "Sam Adams" <smada...@gmail.com>
Subject: [OMPI users] threading
To: us...@open-mpi.org
Message-ID:
        <faa2718c0703210929h3a9b4436wa255e863f1478...@mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

I have been looking, but I haven't really found a good answer about
system level threading.  We are about to get a new cluster of
dual-processor quad-core nodes or 8 cores per node.  Traditionally I
would just tell MPI to launch two processes per dual processor single
core node, but with eight cores on a node, having 8 processes seems
inefficient.



My question is this: does OpenMPI sense that there are multiple cores
on a node and use something like pthreads instead of creating new
processes automatically when I request 8 processes for a node, or
should I run a single process per node and use OpenMP or pthreads
explicitly to get better performance on a per node basis?


--

Regards,
Mohammad Huwaidi

We can't resolve problems by using the same kind of thinking we used
when we created them.
                                                --Albert Einstein
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