<div dir="ltr"><div dir="ltr">On Wed, Feb 10, 2021 at 10:00 AM Edoardo alinovi <<a href="mailto:edoardo.alinovi@gmail.com">edoardo.alinovi@gmail.com</a>> wrote:<br></div><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="auto">Thanks Matthew,<div dir="auto"><br></div><div dir="auto">Probably in my case is a good idea to use parmetis directly as i just need the cell distribution in pre-procrssing. Thanks for the clarification.</div><div dir="auto"><br></div><div dir="auto">On an affine side, it's a while i am interrogating my self about a thing. Let's say i have my cell distribution accross processors from parmetis. Since petsc needs to have the unknows from 1 to N0 hosted by rank 0, N0+1:N2 hosted by rank 2 and so on, what i am doing is relabelling local cells in order to meet this requirement . Is that right? I am wondering if such a way of things is leading to a suboptimal matrix bandwith. What do you think about this?</div></div></blockquote><div><br></div><div>I do not understand. If parmetis gives you a partition, you would have to move the data to match the new partition.</div><div><br></div><div> Thanks,</div><div><br></div><div> Matt</div><div> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="auto"><div dir="auto">Many thanks, </div><div dir="auto"><br></div><div dir="auto">Edoardo </div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Wed, 10 Feb 2021, 13:12 Matthew Knepley, <<a href="mailto:knepley@gmail.com" rel="noreferrer" target="_blank">knepley@gmail.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr"><div dir="ltr">On Wed, Feb 10, 2021 at 4:07 AM Edoardo alinovi <<a href="mailto:edoardo.alinovi@gmail.com" rel="noreferrer noreferrer" target="_blank">edoardo.alinovi@gmail.com</a>> wrote:<br></div><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div>Hello PETSc friends,</div><div><br></div><div>I am working on a code to partition a mesh in parallel and I am looking at parmetis. As far as I know petsc is interfaced with metis and parmetis and I have seen people using it within dmplex. Now, I am not using dmplex, but I have petsc compiled along with my code for the linear system part. I am wondering if there is a way to load up a mesh file in the parmetis format and use petsc to get the elements partitioning only in output. Is that possible?</div></div></div></div></div></blockquote><div><br></div><div>ParMetis does not really have a mesh format. It partitions distributed graphs. Most people want to partition cells in their mesh, and</div><div>then ParMetis would want the graph for cell connectivity. This is not usually what people store, so typically there is a conversion process</div><div>here. If you want to use PETSc for partitioning, and not use DMPlex, the easiest way to do it is to put your cell connectivity in a Mat,</div><div>storing the adjacency graph for cells. Then use MatPartitioning.</div><div><br></div><div> Thanks,</div><div><br></div><div> Matt</div><div> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div>Thank you for the help,</div><div><br></div><div>Edoardo</div></div></div></div></div></blockquote></div>-- <br><div dir="ltr"><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div>What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead.<br>-- Norbert Wiener</div><div><br></div><div><a href="http://www.cse.buffalo.edu/~knepley/" rel="noreferrer noreferrer" target="_blank">https://www.cse.buffalo.edu/~knepley/</a><br></div></div></div></div></div></div></div></div>
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</blockquote></div><br clear="all"><div><br></div>-- <br><div dir="ltr" class="gmail_signature"><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div>What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead.<br>-- Norbert Wiener</div><div><br></div><div><a href="http://www.cse.buffalo.edu/~knepley/" target="_blank">https://www.cse.buffalo.edu/~knepley/</a><br></div></div></div></div></div></div></div></div>