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From: henry@utzoo.UUCP (Henry Spencer)
Newsgroups: net.arch,net.lang.c,net.micro,net.micro.pc,net.micro.68k
Subject: Re: Re: Re: Need 286 "C" benchmark
Message-ID: <5631@utzoo.UUCP>
Date: Sun, 26-May-85 00:57:11 EDT
Article-I.D.: utzoo.5631
Posted: Sun May 26 00:57:11 1985
Date-Received: Sun, 26-May-85 00:57:11 EDT
References: <426@oakhill.UUCP> <8745@microsoft.UUCP> <583@intelca.UUCP> <433@oakhill.UUCP>, <588@intelca.UUCP>
Organization: U of Toronto Zoology
Lines: 30

> Hmmm, once again Dave has submitted a benchmark that requires more than 64K
> of data.  This continued harping on the issue seems to indicate to me that
> maybe Dave realizes that for programs that require less than 64K of data
> that a 12MHz 286 actually keeps pace with the 16.67 MHz 68020.  Of course,
> he might not be saying this at all, and far be it for ME to try to read
> between his lines of code...

It is always possible to find special cases where inferior processors
outperform superior ones, as witness the recent brouhaha about the Z80
outrunning the VAX 780 on function calls.  One of the tricky parts of
benchmarking is deciding what constitutes a special case and what doesn't.

Fifteen years ago, >64KB of data would frequently have been classed as
a special case.  Today, perceptions have changed, and it is not out of
order to penalize the 286 because its performance drops like a rock when
data size goes past 64KB.  Dave's "continued harping" reflects the
importance of the issue.  Without this wart, the 286 would be no worse
than many other ugly processors that mankind copes with.  As it is,
the 286 makes a useful "one-chip PDP11", and copes well with special
dedicated jobs where data requirements are inherently modest, but is
a travesty as a general-purpose computing engine.

Realistic benchmark results for the 286 cannot list a single number as
the completion time for a benchmark.  The only honest way to describe
the thing's performance is by listing *both* small-model and large-model
times.  This accurately conveys the 286's high performance in restricted
cases and its dismally-bad performance in general cases.
-- 
				Henry Spencer @ U of Toronto Zoology
				{allegra,ihnp4,linus,decvax}!utzoo!henry