Hi Mark, On Dec 9, 2010, at 10:13 AM, Mark Howison wrote:
> On Wed, Dec 8, 2010 at 5:38 PM, Leigh Orf <[email protected]> wrote: >> My question is: can I do the round-robin write part without having to open >> and close (h5fopen_f / h5fclose_f) the file for each core? It seems that >> file_id (and the other id's like dset_id, dspace_id etc.) carries with it >> something tangible that links that id to the file itself. I don't think I >> can get away with doing MPI_BCAST of the file_id (and the other id >> variables) to the other cores and use those handles to magically access the >> file created on the root core... right? I am trying to avoid the overhead of >> opening, seeking, closing for each core. > > Quincey, is H5Fcreate/open already using an MPI_BCAST under the covers? Yes, in certain circumstances. > If not, there is another optimization that I think was reported in a > paper on PLFS or Adios about passing a flag to the fopen call on each > MPI task that tells it not to update the creation/modification time > except on the root task. This can greatly reduce the load on the > metadata server for a parallel file system. Interesting, can you send me a reference for this? Quincey _______________________________________________ Hdf-forum is for HDF software users discussion. [email protected] http://mail.hdfgroup.org/mailman/listinfo/hdf-forum_hdfgroup.org
