Prentice Bisbal a écrit :
Can anyone give me a quick comparison of OpenMPI vs. MPICH? I've always
used MPICH (I never liked lam), and just recently heard about OpenMPI.
Anyone here using it?
I use OpenMPI since a few months and run programs like Abinit, Siesta
with success every days (on a small
IB cluster - 100 opteron cores under linux).
I have done some comparisons using M(VA)PICH(2) on IB instead of OpenMPI
and haven't seen any great differences ;
the performances are comparable, for example on a Alltoall, depending on
the message size, sometimes MVAPICH
is better, sometimes OpenMPI is better.
Also, I have to said that OpenMPI is quite appealing because of its ease
of use, a very good web site (FAQs, mailing list),
and has several advantages : it is well integrated with a PBS-like batch
system, a same binary can run on different networks (IB, ethernet)
without recompiling or reliking your application, and there are some
possibilities to exploit numa placement of the tasks, on these
last two points I'm not sure that MPICH can do the same.
But, as the other guys have said before, it is very useful to have the
two implementations on the same cluster.
Another thing : my own experience shows that ISVs usually send you a
binary which is compatible with mpich or mpich2,
but not with OpenMPI.
Bye
Phil.
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