[Mpi3-tools] MPIT 3.1: look up by name

[Bronis R. de Supinski]

I agree with Jeff that this request is a convenience function.
Not only do I think he is right about it not needing to be
performant and that an application could clearly do it
itself but any more efficient implementation could be replicated
at the application layer. For example, the tree-based approach
could be done with one pass over the list that builds the tree.

On Thu, 2 May 2013, Jeff Squyres (jsquyres) wrote:

> On May 1, 2013, at 1:06 AM, "Schulz, Martin" <schulzm at llnl.gov> wrote:
>
>>> Is this just a convenience function?
>>
>> An implementation could store all variables in a tree (or some other more efficient structure) eliminating the need for a loop in favor of a lower complexity lookup algorithm. How severe this problem is, is a different question.
>
> I don't think that efficiency is the issue here -- even for an MPI implementation with thousands of cvars, a loop over them would take microseconds, at most.  More specifically: I was not under the impression that cvar access needed to be performant.
>
> I guess my point is that: regardless of mechanism, this functionality can definitely be implemented in the user application with the current MPIT APIs.  Moving this functionality to *inside* MPIT is a convenience.
>
> I'm not saying this is a good or bad idea -- I'm just making sure we all understand what is being asked.  :-)
>
>> If we want to go for such a function, I wonder, though, if we should return all the arguments from GET_INFO or just the index (that you can then use get the rest of the information). This would could both keep the document (we are mentioning the GET_INFO functions a lot) and the implementations (only one pair of routines with such complex prototypes) simpler.
>>
>> Martin
>>
>>
>>>
>>>
>>> On Apr 30, 2013, at 2:39 PM, Kathryn Mohror <kathryn at llnl.gov> wrote:
>>>
>>>> Hi all,
>>>>
>>>> I've started to work on 3.1 items. The first one is to allow the  look up of variables by name instead of having to iterate through all variables until you find the one you want (assuming you know the name in advance). What do people think of this for supporting that functionality:
>>>>
>>>> MPI_T_CVAR_GET_INFO_NAMED
>>>> 	IN 	     name
>>>> 	OUT     cvar_index
>>>> 	OUT	     verbosity
>>>>   	OUT     datatype
>>>>      OUT      enumtype
>>>>  	OUT	     desc
>>>>      INOUT  desc_len
>>>>      OUT     bind
>>>>      OUT     scope
>>>>
>>>> MPI_T_CVAR_GET_INFO_NAMED behaves similarly to MPI_T_CVAR_GET_INFO except that the lookup is done by control variable name instead of its index. All restrictions and requirements for MPI_T_CVAR_GET_INFO are the same for MPI_GET_CVAR_INFO_NAMED except that the cvar_index is now returned from the function, and name is an input.
>>>>
>>>>
>>>> Then define MPI_T_PVAR_GET_INFO_NAMED in a similar fashion.
>>>>
>>>> Thoughts? Objections?
>>>>
>>>> Kathryn
>>>>
>>>>
>>>> ______________________________________________________________
>>>> Kathryn Mohror, kathryn at llnl.gov, http://people.llnl.gov/mohror1
>>>> CASC @ Lawrence Livermore National Laboratory, Livermore, CA, USA
>>>>
>>>>
>>>>
>>>>
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>>>
>>>
>>> --
>>> Jeff Squyres
>>> jsquyres at cisco.com
>>> For corporate legal information go to: http://www.cisco.com/web/about/doing_business/legal/cri/
>>>
>>>
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>>
>> ________________________________________________________________________
>> Martin Schulz, schulzm at llnl.gov, http://people.llnl.gov/schulzm
>> CASC @ Lawrence Livermore National Laboratory, Livermore, USA
>>
>>
>>
>>
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>
>
> -- 
> Jeff Squyres
> jsquyres at cisco.com
> For corporate legal information go to: http://www.cisco.com/web/about/doing_business/legal/cri/
>
>
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