Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!usc!rpi!crdgw1!sixhub!davidsen
From: davidsen@sixhub.UUCP (Wm E. Davidsen Jr)
Newsgroups: comp.sys.ibm.pc.hardware
Subject: Re: Comparing 486 to 386 Systems
Message-ID: <3670@sixhub.UUCP>
Date: 11 Apr 91 02:35:35 GMT
References: <40409@netnews.upenn.edu> <1991Apr4.062503.1325@agate.berkeley.edu> <1991Apr4.142742.20601@lonex.radc.af.mil> <1991Apr6.021141.5859@cc.helsinki.fi>
Reply-To: davidsen@sixhub.UUCP (bill davidsen)
Organization: *IX Public Access UNIX, Schenectady NY
Lines: 28

In article <1991Apr6.021141.5859@cc.helsinki.fi> osmoviita@cc.helsinki.fi writes:

| But I compared 33 Mhz 486 with 8k cache and 25 MHz 386 with 64k cache. The
| 25 MHz 386 was faster in some tests until I added additional cache to 486.
| Then the performance of 486 was 4-5 times the performance without cache.
| That was only in tests using lots of memory (e.g. 12 MB).

  That sounds like a system without burst mode refresh. A system with
burst mode will typically show a much smaller benefit from cache, no
matter what the access pattern.

  Note: this is not true for all possible patterns, so I am drawing a
conclusion based on limited facts. However, I would be happy if you care
able to confirm this.

  I got some benchmarks on this from the A.I.R. people who advertise in
the back of _Info World_. Since they sell with and without cache, I
assume they don't have a reason to try and make the burst mode machines
look good. I got a chance to try a few tests on a machine at work, and I
agree that a machine with burst mode and no external cache is *usually*
faster than a machine with external cache and no burst mode.

  My opinion and experience only.
-- 
bill davidsen - davidsen@sixhub.uucp (uunet!crdgw1!sixhub!davidsen)
    sysop *IX BBS and Public Access UNIX
    moderator of comp.binaries.ibm.pc and 80386 mailing list
"Stupidity, like virtue, is its own reward" -me