On Wed, Jul 23, 2008 at 02:24:03PM +0200, Gabriele Fatigati wrote: > >You could always effect your own parallel IO (e.g., use MPI sends and > receives to coordinate parallel reads and writes), but >why? It's already > done in the MPI-IO implementation. > > Just a moment: you're saying that i can do fwrite without any lock? OpenMPI > does this?
You use MPI to describe your I/O regions. In fact, these I/O regions can even overlap (something that you can't do efficiently with lock-based approaches). Even better, if you do your I/O "collectively" the MPI library will optimize the heck out of your accesses. When I was learning all this way back when, it took me a long time to get all the details straight (memory types, file views, tiling, independent vs. collective), but a few readings of the I/O chapter of "Using MPI-2" set me straight. ==rob -- Rob Latham Mathematics and Computer Science Division A215 0178 EA2D B059 8CDF Argonne National Lab, IL USA B29D F333 664A 4280 315B
