openmpi versus mpich2

[Rodolfo Aramayo]

And we do no have a port for openmp....;((

Thanks

--R

On Mon, Aug 8, 2011 at 13:25, Jason Swails <jason.swails at gmail.com> wrote:
>
>
> On Mon, Aug 8, 2011 at 2:19 PM, Rodolfo Aramayo <raramayo at gmail.com> wrote:
>>
>> The developer of the package I want to run (Velvet) told me I should
>> just install 'libgomp'
>>
>> Can you guys translate this for me?
>>
>> Is he talking about openmpi or mpich2?? or something else??
>
> Something else.  libgomp is the GNU implementation of the OpenMP
> parallelization scheme.  Note that OpenMPI and mpich2 are both message
> passing interface (MPI) implementations designed for shared and distributed
> memory systems (oversimplified; multi-core computers and many multi-core
> computers networked together) by passing messages between the different
> threads.  OpenMP is a shared memory parallelization scheme that has
> different syntax and design philosophy to MPI.
> OpenMP is (from what I've heard) simpler to write and implement than MPI,
> yet it is limited to shared-memory machines and thus cannot scale as high as
> MPI.
> However, if you're just trying to compile code that someone else has already
> written, you need to know which one they used to parallelize their code and
> link with those libraries.  If the developer of the package you're trying to
> use says to install libgomp, then just do that (or some other OpenMP
> implementation if it's available) and leave MPI alone ;).
> Hope this helps,
> Jason
>
>>
>> Thanks
>>
>> On Mon, Aug 8, 2011 at 09:21, Eric A. Borisch <eborisch at macports.org>
>> wrote:
>> > On Mon, Aug 8, 2011 at 8:57 AM, Jason Swails <jason.swails at gmail.com>
>> > wrote:
>> >> I personally use mpich2 myself, but tend to compile my own MPIs, as the
>> >> multiplicity can get you in trouble (if you link serial libraries to
>> >> MPI
>> >> code, you can run into lots of problems if the compiler version used to
>> >> build the MPI libraries, and therefore the ones you're using to build
>> >> the
>> >> MPI code if you use mpicc/mpif90, is not the same as the compiler
>> >> version
>> >> you used to build the serial libraries).
>> >> HTH,
>> >> Jason
>> >
>> > FWIW, The mpich2 port supports a number of underlying compilers
>> > through the variants... Hopefully your favorite in the list.
>> >  -Eric
>> > --
>> > Eric A. Borisch
>> >
>
>
>
> --
> Jason M. Swails
> Quantum Theory Project,
> University of Florida
> Ph.D. Candidate
> 352-392-4032
>