Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!usc!snorkelwacker!spdcc!merk!xylogics!world!bzs
From: bzs@world.std.com (Barry Shein)
Newsgroups: comp.arch
Subject: Re: I/O, I/O, and off to work I go...
Message-ID: <1989Nov24.033516.16214@world.std.com>
Date: 24 Nov 89 03:35:16 GMT
References: <1128@m3.mfci.UUCP> <1989Nov22.175128.24910@ico.isc.com> <3893@scolex.sco.COM>
Distribution: usa
Organization: The World @ Software Tool & Die
Lines: 52
In-Reply-To: seanf@sco.COM's message of 23 Nov 89 21:25:24 GMT


I've heard these I/O arguments for years. I think the first
centralized computing czar who ever saw a micro harumpphed "Oh yeah,
but how is it on I/O?"

It's true that mainframes, by definition, have awesome I/O relative to
anything else.

What I wonder is, how long before the micros just tear away this
barrier? I agree it'll be a long time before you have the I/O
*systems* that larger machines have, if ever (these days it's common
for mainframes to be ordered with 1TB disk farms, and backup
facilities, that would probably crowd your office.)

But pure I/O performance, measured blindly, on micros with a few
hundred to 1GB or so of disk?

I stress "measured blindly" because I'd consider all sorts of disk
buffering/caching to be fair play. Particularly if they're biased
towards the single-user system so the mainframe/mini couldn't just
implement the methods and jump back ahead. I'm sure such methods
exist, memory scheduling in large time sharers is much harder than in
single or very few user systems.

For example, we'll probably start to see 128MB main memory
workstations in the next couple of years as common. With effective
buffering and inevitably faster controllers and multi-ported memory
designs (?) how long do you think it will be before the difference
between micros/minis/mainframes starts to seem insignificant?

A better question: How fast is fast? How will we know? What's the
current situation? I don't think there are any widely accepted
benchmarks (Nelson? Aims?) I guess when it becomes the marketing rage
the benchmarks will show up.

I remember when they rolled in a 30MIPS 3090 and folks were sure the
mainframe crowd had gotten years ahead of the under-$100K bunch on
CPU. They were right, about two or three years ahead...and they're not
really keeping their heads above water on that front anymore (what's
single CPU performance on a 3090J?)

Or is I/O performance in micros like the weather, everyone talks about
it but no one does anything about it? NeXT made a lot of noise about
"mainframe I/O performance", but I had one of those systems for a
while and I didn't see anything impressive in their disk performance.

Just another windmill waiting to be toppled? Then what?
-- 
        -Barry Shein

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