Hi, Rob Latham <[email protected]> writes: >> our Fortran code works with double precision data, but recently I have >> added the possibility of saving the data to files in single >> precision. In our workstation there is no problem with this and the >> writing time in either double or single precision is basically the >> same. But in a cluster that uses GPFS the writing to single precision >> slows down drastically. > > When the type-in-memory is different from the type-in-file, HDF has to break > collective i/o. there are some property lists you can interrogate to confirm > this (H5Pget_mpio_no_collective_cause; returns a bitfield you'll have to parse > yourself, unless HDF has provided a "flags to string" routine that I do not > know > about) > > In such cases you'll see better performance if you convert your type in memory > then write.
OK, I see. I'll try to figure out some alternative way then, because the performance penalty when saving as single precision is not acceptable at the moment. Thanks, -- Ángel de Vicente http://www.iac.es/galeria/angelv/ --------------------------------------------------------------------------------------------- ADVERTENCIA: Sobre la privacidad y cumplimiento de la Ley de Protección de Datos, acceda a http://www.iac.es/disclaimer.php WARNING: For more information on privacy and fulfilment of the Law concerning the Protection of Data, consult http://www.iac.es/disclaimer.php?lang=en _______________________________________________ Hdf-forum is for HDF software users discussion. [email protected] http://lists.hdfgroup.org/mailman/listinfo/hdf-forum_lists.hdfgroup.org Twitter: https://twitter.com/hdf5
