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From: alan@uc.msc.edu (Alan Klietz)
Newsgroups: comp.parallel
Subject: Re: Byte order in tight coupled systems.
Message-ID: <1991Jun25.220046.11328@hubcap.clemson.edu>
Date: 24 Jun 91 21:45:47 GMT
References: <1991Jun18.173855.29052@hubcap.clemson.edu> <1991Jun24.122015.19112@hubcap.clemson.edu>
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In article <1991Jun24.122015.19112@hubcap.clemson.edu> becker!bdb@uunet.UU.NET (Bruce D. Becker) writes:
<
<	You might want to think about trying to
<	adapt Sun's XDR system to your problem.
<	XDR is a data-representation language
<	which has C-like syntax, and which was
<	designed to handle exactly such problems.

Yes, but XDR is sloow.  The overhead of a procedure call per item is too
much, esp for regular data like arrays. 

XDR wants to build data structures by composing XDR functions for each object.
To get decent performance on a vector or parallel machine, you have to rewrite
it to make it "flat" so that the compiler can recognize the regularity of the
data layout and generate decent code.  Perhaps the compilers will be smart 
enough to this automatically someday, but not yet..

--
Alan E. Klietz
Minnesota Supercomputer Center, Inc.
1200 Washington Avenue South
Minneapolis, MN  55415
Ph: +1 612 626 1737	       Internet: alan@msc.edu

-- 
=========================== MODERATOR ==============================
Steve Stevenson                            {steve,fpst}@hubcap.clemson.edu
Department of Computer Science,            comp.parallel
Clemson University, Clemson, SC 29634-1906 (803)656-5880.mabell