[mpich-discuss] IBM BG/Q collectives

[Jen B]

Thank you for your answers and helpful suggestions, Rob and Jeff!

I have my last question I hope someone could help me clarify. So I get
algorithm names for MPI collectives. Is there any convention for them? I
did not find this information in the redbook. For example, for some of the
algorithm names I get "SCATTER_MPICH", so I think this means that if the
algorithm name ends with "_MPICH" then this is using the algorithm from
MPICH, not the ones optimized for BG/Q. Is this correct?

Thank you!
Jen


On Thu, Nov 19, 2015 at 5:49 PM, Jeff Hammond <jeff.science at gmail.com>
wrote:

> 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 <jenbna at gmail.com> 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 <jeff.science at gmail.com>
>> 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 <jenbna at gmail.com> 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
>>> jeff.science at gmail.com
>>> http://jeffhammond.github.io/
>>>
>>> _______________________________________________
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>>
>>
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>
>
>
> --
> Jeff Hammond
> jeff.science at gmail.com
> http://jeffhammond.github.io/
>
> _______________________________________________
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