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<p>I'm not sure if this is exactly what the original user is referring to, but it is possible to have two separate codes communicate using MPI through the dynamic processes in MPI-2. Essentially, one program starts up on N processors and begins running and
gets an MPI_COMM_WORLD. It then spawns another executable on M different processors and that new executable will call MPI_INIT and also get its own MPI_COMM_WORLD. So you have two, disjoint MPI_COMM_WORLD's that get linked together through a newly created
intercommunicator. <br>
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<p>I've used this to couple a structural mechanics code to our fluid dynamics solver for example. It sounds like that is similar to what is being done here. <br>
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<p>How that would interact with coprocessing is beyond my knowledge though. It does sound like an interesting problem and one I would be very curious to find out the details.</p>
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<p>Tim<br>
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<div id="divRplyFwdMsg" dir="ltr"><font style="font-size:11pt" color="#000000" face="Calibri, sans-serif"><b>From:</b> ParaView <paraview-bounces@paraview.org> on behalf of Andy Bauer <andy.bauer@kitware.com><br>
<b>Sent:</b> Wednesday, May 18, 2016 10:52 AM<br>
<b>To:</b> Ufuk Utku Turuncoglu (BE)<br>
<b>Cc:</b> paraview@paraview.org<br>
<b>Subject:</b> Re: [Paraview] capability of ParaView, Catalyst in distributed computing environment ...</font>
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<div>Hi,<br>
<br>
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<div>I'm a bit confused. MPI_COMM_WORLD is the global communicator and as far as I'm aware, can't be modified which means there can't be two different communicators.<br>
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Catalyst can be set to use a specific MPI communicator and that's been done by at least one code (Code_Saturne). I think they have a multiphysics simulation as well.
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Cheers,<br>
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Andy<br>
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<div class="gmail_extra"><br>
<div class="gmail_quote">On Wed, May 18, 2016 at 5:22 AM, Ufuk Utku Turuncoglu (BE)
<span dir="ltr"><<a href="mailto:u.utku.turuncoglu@be.itu.edu.tr" target="_blank">u.utku.turuncoglu@be.itu.edu.tr</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex; border-left:1px #ccc solid; padding-left:1ex">
Hi All,<br>
<br>
I just wonder about the capability of ParaView, Catalyst in distributed computing environment. I have little bit experience in in-situ visualization but it is hard for me to see the big picture at this point. So, i decided to ask to the user list to get some
suggestion from the experts. Hypothetically, lets assume that we have two simulation code that are coupled together (i.e. fluid-structure interaction) and both of them have their own MPI_COMM_WORLD and run on different processors (model1 runs on MPI rank 0,1,2,3
and model2 runs on 4,5,6,7). What is the correct design to create integrated in-situ visualization analysis (both model contributes to same visualization pipeline) in this case? Do you know any implementation that is similar to this design? At least, is it
possible?<br>
<br>
In this case, the adaptor code will need to access to two different MPI_COMM_WORLD and it could run on all processor (from 0 to 7) or its own MPI_COMM_WORLD (i.e. MPI ranks 8,9,10,11). Also, the both simulation code have its own grid and field definitions (might
be handled via defining different input ports). Does it create a problem in Paraview, Catalyst side, if the multiblock dataset is used to define the grids of the components in adaptor. I am asking because some MPI processes (belongs to adaptor code) will not
have data for specific model component due to the domain decomposition implementation of the individual models. For example, MPI rank 4,5,6,7 will not have data for model1 (that runs on MPI rank 0,1,2,3) and 0,1,2,3 will not have data for model2 (that runs
on MPI rank 4,5,6,7). To that end, do i need to collect all the data from the components? If this is the case, how can i handle 2d decomposition problem? Because, the adaptor code has no any common grid structure that fits for all the model components.<br>
<br>
Regards,<br>
<br>
Ufuk Turuncoglu<br>
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