On Fri, Sep 21, 2012 at 1:19 PM, N.M. Maclaren <[email protected]> wrote:

MPI had no option but to go outside the Fortran and C standards for choice arguments (in the former) and non-blocking transfer for both, but both standards have been updated to enable those aspects of MPI to operate cleanly (though, in the case of C, it's the interpretation, not the wording). But it is very disturbing the way that MPI has started to specify facilities that are seriously incompatible with both language standards and many implementations of them.

I only use MPI from C but I have never seen or heard any evidence to justify this concern. Can you state exactly which MPI functions and semantics are "seriously incompatible with C89 and/or C99"? Exactly which C compilers do not work with MPI? At least in C89 and C99, C doesn't have a memory model but instead inherits this from the hardware. I think this ambiguity is a far bigger issue than anything MPI nonblocking is doing and somehow C manages to be used in many places. The notion that MPI nonblocking send/recv are seriously incompatible with the C language and its implementation in a reasonable C compiler (e.g. GCC) is completely inconsistent with enormous quantities of empirical evidence and sounds like "the sky is falling!" to me. Jeff -- Jeff Hammond Argonne Leadership Computing Facility University of Chicago Computation Institute [email protected] / (630) 252-5381 http://www.linkedin.com/in/jeffhammond https://wiki.alcf.anl.gov/parts/index.php/User:Jhammond