On Wed, Jul 24, 2013 at 11:27 AM, Stephen Wornom <[email protected]>wrote:
> <Yes, though it's much better if you use MPI-IO collective IO. The worst is > <if every process reads a different file. > > The unstructured code I use collects the different core solution on > processor 0 then writes the global solution file to be used at a restart. > When I have a mesh > 2 MillionNodes > I cannot execute as the RAM/core is 3.4Gb which is sufficient to execute > but the virtual memory is too large and I get an error. > > Three questions: > 1- If I used mpi-io to write the file, would that reduce the virtual > memory needed and permit me to run larger meshes? > Yes, since you would not be using only the memory on one process > 2- How would I use the mpi-io routines in the oetsc library to write the > files? The mesh is partitioned using metis. > Make a Vec with your information, and use VecView(). I recognize that this only writes doubles. We do not have infrastructure for MPI/IO with other data types. > 3- Is there a coding example of mpi-io writes that I could use to > understand how petsc functions? > Should not be necessary. Matt > Thanks if advance, > Stephen > > -- > [email protected] > 2004 route des lucioles - BP93 > Sophia Antipolis > 06902 CEDEX > > Tel: 04 92 38 50 54 > Fax: 04 97 15 53 51 > > -- 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
