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Subject: Re: [MTT devel] Extracting transparent data from OMPI
From: Jeff Squyres (jsquyres_at_[hidden])
Date: 2008-02-06 13:06:23


On Feb 6, 2008, at 10:54 AM, Josh Hursey wrote:

>> So to be clear: does the network field not give you what you need?
>
> The network field gives us exactly what we want. The problem is that
> it is not filled in when we run "mpirun foo" since we do not specify
> the BTLs on the command line (unless the INI explicitly specifies it).

There's an OMPI:: funclet for parsing and filling this in:

network = &MPI::OMPI::find_network(&test_command_line(),
&test_executable())

> The problems becomes further complicated when you run something like
> "mpirun -mca btl openib,tcp,self" where the 'tcp' BTL is not going to
> be used due to exclusivity (at least that is what I'm told), so we
> miss report the BTLs used in this case.

True. I don't think that MTT can figure that out, though -- this is a
case of a user error, IMHO.

>>> For the configure options we *could* parse the config.log to extract
>>> this data. The question is, if we did this, what do we want to look?
>>> And is this something we want to do? Is there another way?
>>
>> I think having a network-like field for the MPI install section might
>> be good, and possibly have an OMPI:: funclet to automatically do the
>> parsing. But we need to be mindful of MPIs that won't have a
>> configure script, so what information goes there might be dubious (or
>> just empty?).
>
> Yeah I think an Open MPI specific function should do the parsing since
> the configure options we want to grab will be specific to Open MPI. I
> think in the case of no configure script it would just be empty.

Agreed.

>>> For the BTL(s)/MTL this is a much more subtle question since this
>>> depends on the connectivity of the interfaces on a machine, and the
>>> runtime selection logic. If we added a parameter to mpirun (e.g. "--
>>> showme connectivity") that displayed connectivity information to
>>> stdout (or a file) would this be useful? What should it look like?
>>
>> Ya, this is on my to-do list. IB CM stuff in the openib BTL has been
>> consuming my time recently (much more complicated than I originally
>> thought); I swear I'll be getting to the connectivity map issue
>> before
>> v1.3...
>
> Is there a bug about this somewhere? There is a slim chance that I
> (maybe Tim P) could help with this effort as well in the near term
> (next month). For the simple case we could just dump the connectivity
> information from Rank 0, then the more complex case will be full
> mapping.

I could swear that there was a ticket about this, but now I can't find
it. :-\ I'll go file one now...

Here we go: https://svn.open-mpi.org/trac/ompi/ticket/1207

I put down some thoughts there. Let's move on from there...

-- 
Jeff Squyres
Cisco Systems