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Subject: Re: [OMPI users] Tuned collectives: How to choose them dynamically? (-mca coll_tuned_dynamic_rules_filename dyn_rules)"
From: Igor Kozin (i.n.kozin_at_[hidden])
Date: 2009-07-23 08:08:38


Hi Gus,
I played with collectives a few months ago. Details are here
http://www.cse.scitech.ac.uk/disco/publications/WorkingNotes.ConnectX.pdf
That was in the context of 1.2.6

You can get available tuning options by doing
ompi_info -all -mca coll_tuned_use_dynamic_rules 1 | grep alltoall
and similarly for other collectives.

Best,
Igor

2009/7/23 Gus Correa <gus_at_[hidden]>:
> Dear OpenMPI experts
>
> I would like to experiment with the OpenMPI tuned collectives,
> hoping to improve the performance of some programs we run
> in production mode.
>
> However, I could not find any documentation on how to select the
> different collective algorithms and other parameters.
> In particular, I would love to read an explanation clarifying
> the syntax and meaning of the lines on "dyn_rules"
> file that is passed to
> "-mca coll_tuned_dynamic_rules_filename ./dyn_rules"
>
> Recently there was an interesting discussion on the list
> about this topic.  It showed that choosing the right collective
> algorithm can make a big difference in overall performance:
>
> http://www.open-mpi.org/community/lists/users/2009/05/9355.php
> http://www.open-mpi.org/community/lists/users/2009/05/9399.php
> http://www.open-mpi.org/community/lists/users/2009/05/9401.php
> http://www.open-mpi.org/community/lists/users/2009/05/9419.php
>
> However, the thread was concentrated on "MPI_Alltoall".
> Nothing was said about other collective functions.
> Not much was said about the
> "tuned collective dynamic rules" file syntax,
> the meaning of its parameters, etc.
>
> Is there any source of information about that which I missed?
> Thank you for any pointers or clarifications.
>
> Gus Correa
> ---------------------------------------------------------------------
> Gustavo Correa
> Lamont-Doherty Earth Observatory - Columbia University
> Palisades, NY, 10964-8000 - USA
> ---------------------------------------------------------------------
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