[MPI3 Fortran] MPI non-blocking transfers
longb at cray.com
Wed Jan 21 16:29:59 CST 2009
N.M. Maclaren wrote:
> Eh? No proposal so far has been completely different. The way that MPI
> is specified, there is no difference between requiring an ASYNCHRONOUS
> attribute and requiring and ASYNCH_EXTERNAL one. Both need a minor
More precisely, no proposals since you have joined the discussion.
There have been proposals in the past that would create a "real" Fortran
interface for MPI that was completely different from the C interface.
It would use assumed-shape dummies. (Solves the copy-in/copy-out
problem.) With the associated descriptors, a large number of the
arguments to MPI routines could be dropped. (Improves on the difficulty
of use problem and reduces coding mistakes.)
> As someone with experience of installing and supporting multiple
> MPI's on multiple different systems, it is thoroughly undesirable.
> every compiler requires special flags to work together with MPI
> transfers, those options are only sometimes documented and then typically
> in a place that only the most expert administrator will find (and no
> that I have met). That is a BIG problem.
I agree that there are problems with the current arrangement. I just
was pointing out that these problems have been solved in some way or
another (perhaps not elegantly). MPI *does* work. Every day in real
production. It it didn't, there would be no motivation to continue
Bill Long longb at cray.com
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Cray Inc., 1340 Mendota Heights Rd., Mendota Heights, MN, 55120
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