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From: Jeff Squyres (jsquyres_at_[hidden])
Date: 2007-10-07 12:53:25


Thanks Paul!

I filed https://svn.open-mpi.org/trac/ompi/ticket/1161 with the
action of renaming the BTL and included a link to your post with the
suggestions.

On Oct 6, 2007, at 11:21 PM, Paul H. Hargrove wrote:

> Jeff Squyres wrote:
>> On Oct 6, 2007, at 9:59 PM, Andrew Friedley wrote:
>>
>>
>>>> Yes, I very much care about backward compatibility of the openib
>>>> name
>>>> and MCA parameters... This is, as I see it, the biggest issue with
>>>> changing the name. Stuff like this has to work:
>>>>
>>>> mpirun --mca btl openib,self ...
>>>> mpirun --mca btl_openib_foo 32 ...
>>>>
>>> Ah that could be fun, do you have ideas or should I try to figure
>>> this
>>> out myself?
>>>
>>
>> I was kinda assuming that it would be some kind of aliasing in the
>> MCA parameter engine...? I dunno -- I hadn't really thought about
>> this much.
>>
>
> If creating an aliasing mechanism in the parameter engine for
> supporting
> renamed parameters (as opposed to a "macro" facility) , I have some
> suggestions based on past experience/mistakes:
>
> 1) If the parameters include both the "aliased from" and "aliased to"
> parameter names in the same invocation, consider this a fatal error.
> Doing this does require a little bit of extra work, but the extremely
> confusing/non-obvious behavior that is allowed otherwise is a big
> headache. If there is a need to specify the same "effective"
> parameter
> multiple times (e.g. command line to override a defaults file), then
> force the user to use the same parameter name in both/all parameter
> sources. You may wish to offer an option to suppress this behavior if
> one thinks it is to paranoid/draconian.
>
> 2) Consider having something like gcc's deprecated attribute to
> print a
> warning that the parameter the user has specified has been replaced
> by a
> new name, and that support for the old name will be removed in OpenMPI
> version x.y. After all, you don't want the aliases to grow without
> bound, and we do want to see OpenMPI in use for many years to come.
>
> -Paul
>
> --
> Paul H. Hargrove PHHargrove_at_[hidden]
> Future Technologies Group
> HPC Research Department Tel: +1-510-495-2352
> Lawrence Berkeley National Laboratory Fax: +1-510-486-6900
>
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-- 
Jeff Squyres
Cisco Systems