Path: utzoo!attcan!uunet!crdgw1!crdos1!davidsen
From: davidsen@crdos1.crd.ge.COM (Wm E Davidsen Jr)
Newsgroups: comp.arch
Subject: Re: SPECmarks for RS/6000 systems - lies???
Message-ID: <2738@crdos1.crd.ge.COM>
Date: 5 Oct 90 16:44:06 GMT
References: <4734@lure.latrobe.edu.au> <41935@mips.mips.COM>
Reply-To: davidsen@crdos1.crd.ge.com (bill davidsen)
Organization: GE Corp R&D Center, Schenectady NY
Lines: 34

In article <41935@mips.mips.COM> mash@mips.COM (John Mashey) writes:

| But, anyway, let us be careful not to characterize something as lies,'
| when there are perfectly legitimate reasons, well within the rules,
| that might explain this.  A far more interesting question is to
| ask, in general, of all of us is:
| 	What effort does it take to achieve given levels of performance?
| 	What's the difference between -O and -O5 -x -y -z5000 -q -k300....?

  This is a really good point, and at the risk of overkill I will remind
readers of some benchmark results which were labeled as lies, although
they turned out to be true.

  One of the early Radio Shack 386 systems (3000, perhaps) was
benchmarked by RS and the results published. Later many other people
tried to get those numbers and couldn't. Lots of accusations followed.
It turns out that at boot time the ammount of memory is tested, and
interleave turned on if there was a multiple of 4MB in the machine (or
2MB, memory is dim).

  At any rate when the system was run with less memory, say 1MB and DOS,
the results were a lot slower, since every memory access now had 1-2
wait states added. Not the fault of RS, they clearly stated the memory
size, people just didn't realize that it made a 30% (or so) improvement
in performance for many things.

  As John says, let's be very careful not to confuse the results of
carefully tweaked compilations, links, and kernel configuration with
something which a user just can't do. Tweaking machines and options is
an art, and if it wasn't a lot of us would be reading want ads instead
of netnews.
-- 
bill davidsen	(davidsen@crdos1.crd.GE.COM -or- uunet!crdgw1!crdos1!davidsen)
    VMS is a text-only adventure game. If you win you can use unix.