On Tue, Dec 21, 2010 at 5:49 AM, Thomas Witkowski <span dir="ltr"><<a href="mailto:thomas.witkowski@tu-dresden.de">thomas.witkowski@tu-dresden.de</a>></span> wrote:<br><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
Hi,<br>
<br>
I have a not directly PETSc related question, but I hope to get some answer from the community here. In my FEM code, I make use of ParMETIS to partition the mesh. I make direct use of this library and not of PETSc's ParMETIS integration. The initial partition is always fine, but I use the ParMETIS_V3_AdaptiveRepart function for repartition the mesh due to local mesh adaption. In most cases, the result is fine, but there are two points, where I have trouble with:<br>
<br>
1) Sometimes ParMETIS generates empty partitions, i.e., a processor has zero mesh elements. This is something my code cannot handle. Is this a bug or a feature? If it is a feature, is there any possiblity to disable it?<br>
</blockquote><div><br></div><div>ParMetis has a balance constraint if you weight vertices. This will enforce equal size partitions.</div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
2) In most cases the specific partitions are not connected. If I put all data to ParMETIS in a correct way, is this okay? My code can handle it, but is slows down the computation due to larger interior boundaries and therefore to more communications.<br>
</blockquote><div><br></div><div>ParMetis minimizes the overall boundary size, so I do not understand how you could see this slowdown.</div><div><br></div><div> Matt</div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
Does anyone of you know an answer to these question? Is there a debug mode in ParMETIS, where I can see which data is set to its function calls?<br>
<br>
Regards,<br><font color="#888888">
<br>
Thomas<br>
</font></blockquote></div><br><br clear="all"><br>-- <br>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<br>