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Subject: Re: [OMPI users] Why is the eager limit set to 12K?
From: Shamis, Pavel (shamisp_at_[hidden])
Date: 2012-05-09 12:42:08


>
> Thanks a lot for the clarification. Do you know if this empirical tests
> has been published somehow/somewhere?

I think it was published in very early OSU/MVAPICH related papers.

Regards,
P.

>
> cheers, Simone
>
>>
>> On May 7, 2012, at 9:25 AM, Simone Pellegrini wrote:
>>
>>> Hello,
>>> I have one of those 1M dollar questions I guess, but why the eager limit threshold for Infiniband is set to 12KB by default in OpenMPI? I would like to know where this value comes from. I am not wondering whether this is a good setting for this parameter, but just why this is considered to be a good trade-off for all Infiniband clusters. What I would like to know at the end of the story is whether this is an empirical value or if there are architecture characteristics of IB which make this value come out of pen and paper work (any pointer would be appreciated).
>>>
>>> thanks in advance for the reply.
>>>
>>> regards,
>>> Simone P.
>>>
>>>
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>>
>>
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