On Fri, Apr 4, 2014 at 4:34 PM, Rob Latham <[email protected]> wrote: > > > On 04/04/2014 10:08 AM, Matthew Turk wrote: > >>> What kind of incompatibilities? Are these bugs in the MPI-IO >>> implementation? >> >> >> No, they're just incompatibilities with it in Enzo. Here's an example >> thread from the mailing list. >> >> https://groups.google.com/d/msg/enzo-users/2as4N0iOS5Y/LftkV0oXuHEJ > > > well that *particular* build error is because of a mix-mash of namespaces. > no one needs mpicxx.h anyway, so you can add "-DMPICH_SKIP_MPICXX > -DOMPI_SKIP_MPICXX" to your MACH_DEFINES or MACH_CPPFLAGS. > > Was that seriously the only reason enzo hasn't looked at using parallel > hdf5?
To be perfectly candid, the reason Enzo hasn't looked at using parallel HDF5 is probably because the person who designed the IO system (who has, very sadly, now passed on) saw no measurable benefit to it, and structured the IO in such a way that we did not use it. There is only one time that multiple processors read from the same file, which is during the initialization of a simulation that utilizes ParallelRootGridIO. Once that has completed, the grids are decomposed across processors, and each processor writes to a single file. As it stands, traversing the leaf nodes in large simulations is already extremely costly, and unless we address that I do not think moving to a monolithic file per snapshot is going to provide us with much benefit, as it would exacerbate that problem. (I would be keen to be proven wrong on this, however.) All of that aside, I apologize for jumping in and re-directing the conversation to Enzo rather than to the issue that John brought up initially. The enzo-dev mailing list ( https://groups.google.com/forum/#!forum/enzo-dev ) would be a good place to continue further discussions. -Matt > > ==rob > > >> >> -Matt >> >>> >>> >>> ==rob >>> >>> -- >>> Rob Latham >>> Mathematics and Computer Science Division >>> Argonne National Lab, IL USA >>> >>> _______________________________________________ >>> Hdf-forum is for HDF software users discussion. >>> [email protected] >>> >>> http://mail.lists.hdfgroup.org/mailman/listinfo/hdf-forum_lists.hdfgroup.org >> >> >> _______________________________________________ >> Hdf-forum is for HDF software users discussion. >> [email protected] >> >> http://mail.lists.hdfgroup.org/mailman/listinfo/hdf-forum_lists.hdfgroup.org >> > > -- > Rob Latham > Mathematics and Computer Science Division > Argonne National Lab, IL USA > > _______________________________________________ > Hdf-forum is for HDF software users discussion. > [email protected] > http://mail.lists.hdfgroup.org/mailman/listinfo/hdf-forum_lists.hdfgroup.org _______________________________________________ Hdf-forum is for HDF software users discussion. [email protected] http://mail.lists.hdfgroup.org/mailman/listinfo/hdf-forum_lists.hdfgroup.org
