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To: dyson@FreeBSD.ORG
cc: garbanzo@hooked.net (Alex), current@FreeBSD.ORG
Subject: Re: Pentium optimizations 
In-reply-to: Your message of "Wed, 17 Dec 1997 01:23:22 EST."
             <199712170623.BAA00476@dyson.iquest.net> 
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Date: Wed, 17 Dec 1997 08:42:33 -0700
From: "Russell L. Carter" <rcarter@consys.com>
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}Alex said:
}> 
}> The response(s) I got to my "I'm a newbie, anyone know about this problem"
}> was basically met with "well no FreeBSD developers have contacted us, and
}> if they did we'd accept/commit/whatever some changes..".
}> 
}I expected that they would be cooperative (the EGCS group appears to be
}culturally similar to us (modulo-GPL).)  John Polstra is really our
}most active ELF/Compiler person, and so he would likely be a better
}"official FreeBSD" interface.  He is also less politically likely to
}insert his foot into his eating orifice.  I do have some PPro mods,
}and they appear to help performance on average.  The PPro is a
}really wierd creature (like the K6.)  The darned processor does so
}much optimization, it appears to be insensitive to code mods.  There are
                                      ^^^^^^^^^^^^^^^^^^^^^^^^
Noticed that too, eh?  Recently I hacked up some of the SSLeay asm 
code and while I could improve P5 performance about 30%, the best
that I could do, with a lot of effort was maybe 4% for PII and PPro.
The out-of-order execution seems to help a lot.  Oh, and the P5
specific asm actually makes the PPro slow down over the C source;
not good tidings for ye merry old tuners.

}areas of reasonable payoffs, and lots of "obvious" optimizations that
}end up being neutral.

Yep.  I wouldn't worry too much about other people's claims about code
optimized for Pentium Pro.

Russell

}
}-- 
}John                  | Never try to teach a pig to sing,
}dyson@freebsd.org     | it just makes you look stupid,
}jdyson@nc.com         | and it irritates the pig.