<meta charset="utf-8">> Berk: Do you have the ability to mark a node as "owned" by one partition and as "ghost" on<br>> other partitions?<div><br></div><div>Yes! We classify processes as master and slaves according to their ranking numbers. After this we can assign the shared node to a master (which will take care of shared computations) and tell the slave process that this node is being shared with a master (and the slave process will consider it as a "ghost" for computations). </div>
<div><div><br></div><div>The ideas we used in our parallel solver were taken from the following article: </div><div><br></div><div>Karanam, A. K., Jansen, K. E. and Whitinig, C. H., "Geometry Based Pre-processor for Parallel Fluid Dynamic Simulations Using a Hierarchical Basis", Engineering with Computers (24):17-26, 2008.</div>
<div><br></div><div>This article was made available from the author in <a href="http://www.scorec.rpi.edu/REPORTS/2007-3.pdf">http://www.scorec.rpi.edu/REPORTS/2007-3.pdf</a> (Figures 7 to 9 explain the communication method between processes),</div>
<div><br></div><div>Regards</div><div><br></div><div>Renato.</div><div><br><br><div class="gmail_quote">On Tue, Mar 1, 2011 at 12:24 PM, Berk Geveci <span dir="ltr"><<a href="mailto:berk.geveci@kitware.com">berk.geveci@kitware.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">Hi Renato,<br>
<div class="im"><br>
> I think I'm missing something.... you said cells only?!<br>
> If I understood this subject correctly, a cell should be considered ghost if<br>
> it's held by more than one partition/process, isn't it?! In this case,<br>
> there'll be an overlapped layer of elements. The problem is that my MPI<br>
> solver does not make use of this overlapped layer of cells/elements.<br>
<br>
</div>Yep. You understood correctly. Ghost cells are very common for finite<br>
difference calculations but not as common for finite elements.<br>
<div class="im"><br>
> It only<br>
> has nodes/points that are shared by processes. This explains why I asked by<br>
> a ghost node (shared node would be more appropriated to define such kind of<br>
> node).<br>
> Can I consider a cell as ghost if it touches the parallel interface (without<br>
> overlapping)? Would it work?<br>
<br>
</div>Nope. Then you'd start seeing gaps. The right thing to do is for<br>
ParaView to support ghost points (nodes) better. However, this is<br>
non-trivial in some cases. For removing internal interfaces, it is<br>
sufficient to mark points as ghosts. However, for accurately<br>
performing statistics, you need to make sure that you count all points<br>
only once, which requires assigning ghost nodes to processes. So a<br>
replicated node would be marked as ghost (a better word is shared) and<br>
also owned by a particular process. We are going to improve VTK's<br>
ghost level support. This is something we'll support. However, it will<br>
be up to the simulation to produce the write output. Do you have the<br>
ability to mark a node as "owned" by one partition and as "ghost" on<br>
other partitions?<br>
<br>
Best,<br>
<font color="#888888">-berk<br>
</font></blockquote></div><br><br clear="all"><br>-- <br>Renato N. Elias<div>=============================================</div><div>Professor at Technology and Multilanguage Department (DTL)</div><div>Federal Rural University of Rio de Janeiro (UFRRJ)</div>
<div>Nova Iguaçu, RJ - Brazil</div><div><br>=============================================<br>Researcher at High Performance Computing Center (NACAD)<br>Federal University of Rio de Janeiro (UFRJ)<br>Rio de Janeiro, Brazil<br>
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