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Subject: Re: [OMPI users] OpenMPI with SGE: "-np N" for mpirun needed?
From: Jiri Polach (jiri.polach_at_[hidden])
Date: 2012-05-09 16:40:11


>> Dear all,
>>
>> is "-np N" parameter needed for mpirun when running jobs under SGE
>> environment? All examples in
>>
>> http://www.open-mpi.org/faq/?category=running#run-n1ge-or-sge
>>
>> show that "-np N" is used, but in my opinion it should be redundant:
>> mpirun should determine all parameters from SGE environment anyway. If
>> there is "no need to specify what nodes to run on" (as stated in FAQ),
>> it should not be necessary to specify the number of processors either.
>>
>> I ran some tests and it seems that mpirun correctly gets number of
>> processors from SGE, but I would like to have some more solid
>> confirmation.
>
> You might want to use a smaller number of processors than those made
> available by SGE.

Thanks for replying. I can imagine that in some special cases it might
be useful to request N processors from SGE and than use M<N; in such
cases I would specify "-np M" for mpirun, of course.

But this does not answer the question - if I just want to use as many
processors as I request from SGE - do I need to specify "-np N" for
mpirun or not?

Jiri Polach

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