Sorry for not replying earlier, but I missed this e-mail due to the APS March Meeting.
The GPFS file system on BG/P does a poor job at handling writes to more than one file per node. My guess is that Gabriele was running QE in either dual or VN mode (2 and 4 MPI tasks per node, respectively). So on BG/P, you basically want to write one file per node (which GPFS is designed to handle) or one big file using MPI-I/O. At ANL, we are thinking about re-writing some of the I/O using parallel I/O (e.g. HDF5, Parallel NetCDF). The simplest approach, though highly unportable, is to use the MPI I/O directly. Has anyone on this list worked on parallel I/O with QE? Or have any strong opinions on this issue? On Wed, Mar 30, 2011 at 11:57 AM, Paolo Giannozzi <giannozz at democritos.it> wrote: > > On Mar 30, 2011, at 11:20 , Gabriele Sclauzero wrote: > >> Do you think that having an additional optional level of I/O >> (let's say that it might be called "medium") > > I propose 'rare', 'medium', 'well done' > >> would be too confusing for users? > > some users get confused no matter what > >> I could try to implement and test it. > > ok: just follow the "io_level" variable. Try first to understand > what the actual behavior is (the documentation is not so > clear on this point) and then think what it should be, if you > have some clear ideas > > P. > --- > Paolo Giannozzi, Dept of Chemistry&Physics&Environment, > Univ. Udine, via delle Scienze 208, 33100 Udine, Italy > Phone +39-0432-558216, fax +39-0432-558222 > > > > > _______________________________________________ > Pw_forum mailing list > Pw_forum at pwscf.org > http://www.democritos.it/mailman/listinfo/pw_forum > -- Nichols A. Romero, Ph.D. Argonne Leadership Computing Facility Argonne, IL 60490 (630) 447-9793
