On Wed, Aug 06, 2008 at 01:31:09PM -0500, Jason Clinton wrote: > Generally speaking, MPI programs will not be fetching/writing data > from/to storage at the same time they are doing MPI calls so there > tends to not be very much contention to worry about at the node level.
Well... if the MPI program uses collective I/O (maybe they use MPI_File_write_all directly, or they are using collective parallel-NetCDF or parallel-HDF5 calls), it is likely the MPI-IO implementation will optimize that access with "two-pase" buffering. I would like to think this situation is common in high performance I/O, especially when accessing a parallel file system. Some tremendous performance gains can be had with collective I/O. ==rob -- Rob Latham Mathematics and Computer Science Division A215 0178 EA2D B059 8CDF Argonne National Lab, IL USA B29D F333 664A 4280 315B _______________________________________________ Beowulf mailing list, [email protected] To change your subscription (digest mode or unsubscribe) visit http://www.beowulf.org/mailman/listinfo/beowulf
