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Subject: Re: [OMPI users] openmpi (1.2.8 or above) and Intel composer XE 2011 (aka 12.0)
From: Gus Correa (gus_at_[hidden])
Date: 2011-05-27 12:53:07


Eugene Loh wrote:
> On 5/27/2011 4:32 AM, Jeff Squyres wrote:
>> On May 27, 2011, at 4:30 AM, Robert Horton wrote:
>>>> To be clear, if you explicitly list which BTLs to use, OMPI will only
>>>> (try to) use exactly those and no others.
>>> It might be worth putting the sm btl in the FAQ:
>>>
>>> http://www.open-mpi.org/faq/?category=openfabrics#ib-btl
>> Is this entry not clear enough?
>>
>> http://www.open-mpi.org/faq/?category=tuning#selecting-components
> I think his point is that the example in the ib-btl entry would be more
> helpful as a template for usage if it added sm. Why point users to a
> different FAQ entry (which we don't do anyhow) when three more
> characters ",sm" makes the ib-btl entry so much more helpful.
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Hi Jeff, list

I agree with Eugene and Robert.
By all means, please add ",sm" to "openib,self" in:

http://www.open-mpi.org/faq/?category=openfabrics#ib-btl

I am yet to see a situation where you want to run with openib and self,
but exclude sm (except for testing, perhaps when memcpy is broken).

Maybe that is what led Salvatore Podda think there was a
"Law of Least Astonishment" behind the mca parameters syntax,
which would insert "sm" automatically to the other two btl,
which is not really the case.

Like Salvatore, I've got confused by the mca parameter
syntax in the past also.
My recollection is that Jeff wrote the second
FAQ to placate my whining in the list about
to sm or not to sm.

However, the second FAQ clarifies the mca parameter logic,
along with the role of the "^" clause, and IMHO should be kept there:

http://www.open-mpi.org/faq/?category=tuning#selecting-components

My two cents,
Gus Correa