In that case, I remove my objection to this particular RFC. It remains for all other RFCs related to moving any of the BTL move code to the trunk before the critical issues with the BTL move have been sorted out in a temporary branch. This includes renaming functions and such. Perhaps we should have a discussion about those issues during the Forum in a couple weeks?

Brian

On Feb 1, 2009, at 5:37 AM, Jeff Squyres wrote:

I just looked through both opal_bitmap_t and ompi_bitmap_t and I think that the only real difference is that in the ompi version, we check (in various places) that the size of the bitmap never grows beyond OMPI_FORTRAN_HANDLE_MAX; the opal version doesn't do these kind of size checks.

I think it would be fairly straightforward to:

- add generic checks into the opal version, perhaps by adding a new API call (opal_bitmap_set_max_size()) - if the max size has been set, then ensure that the bitmap never grows beyond that size, otherwise let it have the same behavior as today (grow without bound -- assumedly until malloc() fails)

It'll take a little care to ensure to merge the functionality correctly, but it is possible. Once that is done, you can:

- remove the ompi_bitmap_t class
- s/ompi_bitmap/opal_bitmap/g in the OMPI layer
- add new calls to opal_bitmap_set_max_size(&bitmap, OMPI_FORTRAN_HANDLE_MAX) in the OMPI layer (should only be in a few places -- probably one for each MPI handle type...? It's been so long since I've looked at that code that I don't remember offhand)

I'd generally be in favor of this because, although this is not a lot of repeated code, it *is* repeated code -- so cleaning it up and consolidating the non-Fortran stuff down in opal is not a Bad Thing.


On Jan 30, 2009, at 4:59 PM, Ralph Castain wrote:

The history is simple. Originally, there was one bitmap_t in orte that was also used in ompi. Then the folks working on Fortran found that they had to put a limit in the bitmap code to avoid getting values outside of Fortran's range. However, this introduced a problem - if we had the limit in the orte version, then we limited ourselves unnecessarily, and introduced some abstraction questions since orte knows nothing about Fortran.

So two were created. Then the orte_bitmap_t was blown away at a later time when we removed the GPR as George felt it wasn't necessary (which was true). It was later reborn when we needed it in the routed system, but this time it was done in opal as others indicated a potential more general use for that capability.

The problem with uniting the two is that you either have to introduce Fortran-based limits into opal (which messes up the non- ompi uses), or deal with the Fortran limits in some other fashion. Neither is particularly pleasant, though it could be done.

I think it primarily is a question for the Fortran folks to address - can they deal with Fortran limits in some other manner without making the code unmanageable and/or taking a performance hit?

Ralph


On Jan 30, 2009, at 2:40 PM, Richard Graham wrote:

This should really be viewed as a code maintenance RFC. The reason this came up in the first place is because we are investigating the btl move, but these are really two very distinct issues. There are two bits of code that have virtually the same functionality - they do have the same interface I am
told.  The question is, is there a good reason to keep two different
versions in the repository ? Not knowing the history of why a second
version was created this is an inquiry.  Is there some performance
advantage, or some other advantage to having these two versions ?

Rich


On 1/30/09 3:23 PM, "Terry D. Dontje" <terry.don...@sun.com> wrote:

I second Brian's concern. So unless this is just an announcement that this is being done on a tmp branch only until everything is in order I
think we need further discussions.

--td

Brian Barrett wrote:
So once again, I bring up my objection of this entire line of moving
until such time as the entire process is properly mapped out.  I
believe it's premature to being moving around code in preparation for a move that hasn't been proven viable yet. Until there is concrete
evidence that such a move is possible, won't degrade application
performance, and does not make the code totally unmaintainable, I
believe that any related code changes should not be brought into the
trunk.

Brian


On Jan 30, 2009, at 12:30 PM, Rainer Keller wrote:

On behalf of Laurent Broto

RFC: Move of ompi_bitmap_t

WHAT: Move ompi_bitmap_t into opal or onet-layer

WHY: Remove dependency on ompi-layer.

WHERE: ompi/class

WHEN: Open MPI-1.4

TIMEOUT: February 3, 2009.

-------------------------------------
Details:
WHY:
The ompi_bitmap_t is being used in various places within
opal/orte/ompi. With
the proposed splitting of BTLs into a separate library, we are currently
investigating several of the differences between ompi/class/* and
opal/class/*

One of the items is the ompi_bitmap_t which is quite similar to the
opal_bitmap_t.
The question is, whether we can remove favoring a solution just in opal.

WHAT:
The data structures in the opal-version are the same,
so is the interface,
the implementation is *almost* the same....

The difference is the Fortran handles ;-]!

Maybe we're missing something but could we have a discussion, on why
Fortran
sizes are playing a role here, and if this is a hard requirement, how
we could
settle that into that current interface (possibly without a notion of
Fortran,
but rather, set some upper limit that the bitmap may grow to?)

With best regards,
Laurent and Rainer
--
------------------------------------------------------------------------
Rainer Keller, PhD                  Tel: (865) 241-6293
Oak Ridge National Lab          Fax: (865) 241-4811
PO Box 2008 MS 6164           Email: kel...@ornl.gov
Oak Ridge, TN 37831-2008    AIM/Skype: rusraink






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--
Jeff Squyres
Cisco Systems

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