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Subject: [OMPI users] Setting MCA parameter from within program
From: Roland Schulz (roland_at_[hidden])
Date: 2010-01-14 15:08:14


Hi all,

is it possible to set MCA parameters from within the MPI program itself? The
FAQ only mentions how to set them through files or environment variables.

I would like to set coll_tuned_use_dynamic_rules and
coll_tuned_alltoall_algorithm.

I assume there is a function to do this in include/opal/mca but I'm not
sure which one. And I couldn't find any documentation explaining it.
I'm aware that this will only work with OpenMPI and is probably not part of
the public api thus the interface might change between version.

My plan is to benchmark all alltoall algorithms at start up and then use
this algorithm for all later AllToAll calls. I have benchmarked that
manually choosing the algorithm can make a large difference. Also all my
alltoall communication is of the same data size thus tuning is easy.

Thanks

> Roland
>

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