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Path: utzoo!linus!philabs!prls!pyramid!micropro!well!mo
From: mo@well.UUCP (Maurice Weitman)
Newsgroups: net.micro.pc,net.micro
Subject: Re: AT hard disk speed: explanation.
Message-ID: <1134@well.UUCP>
Date: Thu, 22-May-86 09:57:54 EDT
Article-I.D.: well.1134
Posted: Thu May 22 09:57:54 1986
Date-Received: Sat, 24-May-86 06:03:13 EDT
References: <346@pilchuck.UUCP>
Reply-To: mo@well.UUCP (Maurice Weitman)
Organization: Whole Earth Lectronic Link, Sausalito CA
Lines: 37
Keywords: Why does it go so fast?
Xref: linus net.micro.pc:7956 net.micro:13310

In article <346@pilchuck.UUCP> del@pilchuck.UUCP (Erik ) writes:
>[]
>
>I don't know what mathematical algorithm relates the above parameters,
>but when you combine them, you do see a speedup of 6-10 times that of
>an XT.
>
>Speaking of mathematical relationships, one that I don't understand is
>why the disk access (copy to nul for example) is that fast, and Norton
>sysinfo says my 9Mhz AT cranks along at 8.7 * PC performance, but my
>compiles only go 4-5 times as fast.
>
First of all, even Norton admits that his SI ratings are misleading at
best, and I say they're worse.  He uses an algorithm which is heavily
weighted for ADDs, I believe, and not really representative of what a
machine will do under many other circumstances.

Next, there are so many variables here (such as disk interleave factors,
number of buffers in your config.sys files, disk controller efficiencies,
etc.) that looking for a mathematical relationship is quite an ambitious
and maybe nebulous project.

If you're really serious about improving throughput in your AT, look into
using one of the disk cacheing programs, consider playing around with the
disk interleave factor, using a ram disk for many of your compiler
files.

If you'd like more specific info, send me e-mail, and I'll try to answer.
(I'm waiting for my '386, too %-) )

maurice
-- 

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