As Rob said, you will find lots of info in the redbook. You can set all sorts of debug options to print out the algorithm(s) used on every call, or prescribe them explicitly (not recommended). Jeff On Thu, Nov 19, 2015 at 8:38 AM, Jen B <[email protected]> wrote:

Thank you for your quick response, Jeff!

I was wondering the values for "short" and "large" message sizes, they've been used throughout the paper but not mentioned explicitly. Do you happen to know if these values are explicitly mentioned somewhere?

Also, if I get the last algorithm name used for the MPI collective routine, is there a way I can for sure tell which algorithm is being used? For example, is there any name formatting convention that is used.

Sorry for so many questions. Any help with any of these questions will be greatly appreciated!

Thank you! Jen

On Wed, Nov 18, 2015 at 6:06 PM, Jeff Hammond <[email protected]> wrote:

...

A binary tree is the implementation of last resort.

See these papers for details of the MPI collective implementations on Blue Gene: - http://dx.doi.org/10.1177/1094342014552086 - http://dx.doi.org/10.1109/HOTI.2009.12 (this is not an inclusive list)

http://lists.mpich.org/pipermail/discuss/2015-March/003754.html has some related info.

Jeff

On Wed, Nov 18, 2015 at 12:53 PM, Jen B <[email protected]> wrote:

...

Hello,

I have a couple of questions about BG/Q collectives and would appreciate any help. I was wondering if Do IBM BG/Q MPI collectives use binomial tree? Once I find the name of the algorithm used by the MPI collective routine using MPIX_Get_last_algorithm_name, is there a quick reference or guide to check how it is implemented?

Thanks! Jen

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-- Jeff Hammond [email protected] http://jeffhammond.github.io/

_______________________________________________ discuss mailing list [email protected] To manage subscription options or unsubscribe: https://lists.mpich.org/mailman/listinfo/discuss

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-- Jeff Hammond [email protected] http://jeffhammond.github.io/ _______________________________________________ discuss mailing list [email protected] To manage subscription options or unsubscribe: https://lists.mpich.org/mailman/listinfo/discuss