On Thu, Feb 16, 2012 at 7:43 AM, Gerard Gorman <g.gorman at imperial.ac.uk>wrote:
> Matthew Knepley emailed the following on 16/02/12 13:29: > > On Thu, Feb 16, 2012 at 3:38 AM, Mohammad Mirzadeh <mirzadeh at gmail.com > > <mailto:mirzadeh at gmail.com>> wrote: > > > > Hi guys, > > > > I'm wondering if there is any implementation > > for ParMETIS_V3_PartGeomKway()? All I can find is the > > implementation for ParMETIS_V3_PartKway and I'm wondering if > > including the vertex positions could help me get a better > > partitioning? > > > > > > As far as communication goes, it will not help. > > > > > > Also I have a general question. Is minimizing number of edge cuts > > essentially the same as minimizing communication? I understand > > that they are related, but communication is proportional to the > > number of ghost points which is not exactly equal (its actually > > less than) to the number of edge cuts. So then is it possible that > > this could actually result in larger number of ghost points, at > > least for some of processors? > > > > > > It of course depends on your problem and the graph you draw, but you > > can always draw a graph > > where the edge cut is exactly your communication. > > > > > > > It might also be interesting to look at Zoltan's hypergraph partitioning > which can better balance communications - > http://www.cs.sandia.gov/zoltan/dev_html/dev_phg.html I would caution you that one thing people are rarely careful about is quantifying the effect of latency vs communication volume. I would bet you $10 that the lion's share of slow down is due to load imbalance/latency rather than communication volume (since comm links are so big). Matt > > Cheers > Gerard > > -- What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead. -- Norbert Wiener -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20120216/67fb7caa/attachment.htm>
