Durga, 


Currently there are two options for porting an interconnect to Open MPI, one would be to use the BTL interface (Byte Transfer Layer). Another would be to use the MTL (Matching Transport Layer). The difference is that the MTL is useful for those APIs which expose matching and other high level semantics such as Portals or MX. If your  API does not support these higher level protocols the BTL would be a good choice. There is some documentation on the BTL interface, one paper describes the various layers at a high level and is found here: http://www.open-mpi.org/papers/ipdps-2006. For more details there was an extensive presentation done at a developers conference and the slides are available here: http://www.open-mpi.org/papers/workshop-2006/wed_01_pt2pt.pdf . This should give you a place to start. Depending on the semantics of your API, writing a BTL can be done quite quickly although interconnect specific optimization can take some time. You mention that you would like to leverage your switch architecture, not sure what you mean by this, is this for point-to-point communication or for collective optimization? If you need collective optimization you would need to touch a few other components in Open MPI but this could also  be done in a modular way. Let me know if you need any other assistance as we would be happy to have another interconnect supported in Open MPI. 

- Galen


On Aug 7, 2006, at 8:18 AM, Durga Choudhury wrote:

Hi All


We have been using the Argonne MPICH (over TCP/IP) on our in-house designed embedded multicomputer for last several months with satisfactory results. Our network technology is custom built and is * not* infiniband (or any published standards, such as Myrinet) based. This is due to the nature of our application. We are currently running TCP/IP over out backplane network and using that as the transport layer of MPICH.


For the next generation of our software release, we are planning to write a low level transport layer to leverage our switch architecture and considering changing the entire MPI protocol stack to openMPI. From what I have found so far, I'd have to write routines to provide services similar to the ones found under ompi/mca/btl/{tcp,mx,...}. I'd like to get some guidance as to how to do this. Is there a document about this? Has anybody in this list done something similar before and if so, what was the difficulty level involved?


Thanks a lot in advance.


Durga

--
Devil wanted omnipresence;
He therefore created communists.

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