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Subject: Re: [OMPI users] Open MPI runtime parameter tuning on a custom cluster
From: Eugene Loh (eugene.loh_at_[hidden])
Date: 2010-07-15 16:50:52

Simone Pellegrini wrote:

> Dear Open MPI community,
> I would like to know from expert system administrator if they know any
> "standardized" way for tuning Open MPI runtime parameters.
> I need to tune the performance on a custom cluster so I would like to
> have some hints in order to proceed in the correct direction.

(I'll try to save Jeff a message as he goes through his inbox...)

I believe there is no standardized way for tuning these parameters.

On the discouraging side, there are very many parameters and they can be
difficult to understand, particularly as there is little to basically no
documentation in a number of cases. In some cases, the trade-offs they
make entail issues that require a detailed understanding of your
particular configuration and application.

On the positive node, the default values of many of these parameters
have been chosen reasonably and so most of the parameters don't need
your attention. There is on-going, gradual progress in helping users
understand tuning -- for example in the OMPI mpirun man page and on the
FAQ -- see the section on "Tuning".