[CP2K:655] Re: cp2k speedup on multicore machines

[Shawn T. Brown]

I have a quad-core Cloverton here, would running these on there with OpenMPI
be useful?


On Jan 30, 2008 7:38 AM, Axel <akoh... at gmail.com> wrote:

>
>
>
> On Jan 30, 1:06 am, Fawzi Mohamed <fa... at gmx.ch> wrote:
> > Hi Axel,
> >
> > nice numbers... just for the record
> >
> > > first off, contrary to fawzi's statement, cpu affinity in OpenMPI has
> > > to be explicitely enabled (e.g. via setting mpi_paffinity_alone=1 in
> > > ~/.openmpi/mca-params.conf).
> >
> > well I didn't say it was automatic :), what I meant was that I knew
> > that both LAM MPI (on which I tested) and openMPI could do it, if
>
> please check the LAM/MPI sources. to the best of my knowledge
> there is no processor affinity in LAM/MPI. i just downloaded the 7.1.4
> sources and there is no call to the respective system or library
> calls.
>
> > configured to do so, and then I told how to have it with LAM MPI...
>
> sorry, but as i wrote, this only tells about locality, _not_
> processor
> affinity. schedulers are still kicking processes around.
>
>
> > > however what both LAM/MPI and
> > > particularly
> > > OpenMPI have activated by default are algorithms that can take
> > > advantage
> > > of locality and that require the correct specification of nodes.
> >
> > yep, I think that Open MPI is the best choice to have a well
> > performing MPI, especially with multiple cores.
> > There is active development and they try to take advantage of the
> > latest hardware.
>
> yes. OpenMPI has the best collective algorithms
> amongst all available open source packages.
>
> cheers,
>   axel.
>
> >
> > ciao
> > Fawzi
> >
>
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