Thanks Matthew, 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.
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? Many thanks, Edoardo On Wed, 10 Feb 2021, 13:12 Matthew Knepley, <[email protected]> wrote: > On Wed, Feb 10, 2021 at 4:07 AM Edoardo alinovi <[email protected]> > wrote: > >> Hello PETSc friends, >> >> 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? >> > > ParMetis does not really have a mesh format. It partitions distributed > graphs. Most people want to partition cells in their mesh, and > then ParMetis would want the graph for cell connectivity. This is not > usually what people store, so typically there is a conversion process > 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, > storing the adjacency graph for cells. Then use MatPartitioning. > > Thanks, > > Matt > > >> Thank you for the help, >> >> Edoardo >> > -- > 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 > > https://www.cse.buffalo.edu/~knepley/ > <http://www.cse.buffalo.edu/~knepley/> >
