Conference nicctr::kap-users

374.0. "Looking for parallel C code" by DECC::VOGEL () Wed Apr 09 1997 22:41

    As part of Digital's effort to return to leadership in the 
    high-performance technical market, we have been adding multiprocessing 
    directives to the DEC C compiler for Digital UNIX.  These are directives 
    which allow the programmer to write code which can run concurrently on 
    multiple processors without restructuring/rewriting the basic
    sequential C source code that embodies the algorithm.  E.g. directives
    identify loops to have their iterations performed in parallel without
    changing the ANSI C language "for" loop or its body as they appear in
    the sequential implemention. We expect that correct use of these directives 
    could greatly improve the run-time performance of certain kinds of 
    applications by allowing that code to execute simultaneously on different 
    processors of a multi-processor machine.  The directives are new 
    #pragmas which are  modeled after the #pragmas available in SGI's Power C 
    compiler which in turn, are modeled after the unfinished work of the 
    ANSI X3H5 committee which attempted to standardize a model of directed 
    parallel decomposition for both C and Fortran a few years back.

    We hope to make an early field test compiler available soon.
    We are currently looking for "real world" test programs we could
    use to test the compiler and run-time system.  Ideally these
    would be C source programs containing SGI's Power C directives
    which would also run on Digital UNIX.  We would also accept source 
    programs that run on Digital UNIX that might be good candidates
    for parallelization - that is, we could easily identify sections
    of code which could be run in parallel, and we could insert the
    directives ourselves.  At this point in time, we are only talking
    about a compiler that processes the directives and generates code
    that would work with a supplied field test run-time library.  We are
    not currently talking about automatically parallelizing sequential
    code or providing other analysis or debugging tools directly supporting
    this kind of code.

    If the source code is very small, it could be posted as a reply.
    If it is larger, a pointer to it could be posted, or mailed to me.

    We are also looking for potential internal field test sites.  
    Internal sites can contact me or post a reply here.

    We do have a working draft of a product spec for the new #pragmas 
    available.  Please contact me if you are interested.

						Thank you,

						Ed Vogel
						DEC C Engineering



    Cross-posted in DECC, DIGITAL_UNIX and KAP_USERS