Hello I have an unstructured FE mesh which I am partitioning using Metis.
In the first case I only use the element partitioning info and discard the nodal partitioning info i.e., the original ordering is same as petsc's global ordering. In the second case I do use the nodal partitioning info and nodes are distributed accordingly. I would expect that in the 2nd scenario the total number of MPI messages (at the end of the solve) would be lower than the 1st. However I see that opposite is true. See the plot at http://stali.freeshell.org/mpi.png The number on the y axis is the last column of the "MPI messages:" field from the -log_summary output. Any ideas as to why this is happening. Does relying on total number of MPI messages as a performance measure even make sense. Please excuse my ignorance on the subject. Alternatively what is a good way to measure how good the Metis partitioning is? Thanks in advance Tabrez
