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From: Aaron Thompson (aaron.p.thompson_at_[hidden])
Date: 2007-06-08 01:11:36


Very interesting, I certainly hope that my problem is this and not
some kind of error. I'll put the program on some more nodes and run
some tests and see what runs fastest.
My only experience so far with MPI is with LAMMPS, and the simulation
I ran had an almost linear speedup from 1 -> 10 machines (11 -> 1.2
hours), very satisfying!

Aaron Thompson
Vanderbilt University
aaron.p.thompson_at_[hidden]

On Jun 7, 2007, at 8:44 PM, Brock Palen wrote:

> We have a few users using DLPOLY with OMPI. Running just fine.
> Watch out what kind of simulation you are doing like all MD
> software, not all simulations are better in parallel. In some the
> comunication overhead is much worse than running on just one cpu. I
> see this all the time. You could try just 2 cpus, on one node some
> times that is ok (memory access vs network access) But its not
> uncommon.
>
> Brock Palen
> Center for Advanced Computing
> brockp_at_[hidden]
> (734)936-1985
>
>
> On Jun 7, 2007, at 8:24 PM, Aaron Thompson wrote:
>
>> Hello,
>> Does anyone have experience using DL POLY with OpenMPI? I've gotten
>> it to compile, but when I run a simulation using mpirun with two
>> dual-
>> processor machines, it runs a little *slower* than on one CPU on one
>> machine! Yet the program is running two instances on each node. Any
>> ideas? The test programs included with OpenMPI show that it is
>> running correctly across multiple nodes.
>> Sorry if this is a little off-topic, I wasn't able to find help on
>> the official DL POLY mailing list.
>>
>> Thank you!
>>
>> Aaron Thompson
>> Vanderbilt University
>> aaron.p.thompson_at_[hidden]
>>
>>
>>
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