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From: khb%chiba@Sun.COM (Keith Bierman - SPD Advanced Languages)
Newsgroups: comp.arch
Subject: Re: specmarks
Summary: voodoo ... just say NO
Message-ID: <126868@sun.Eng.Sun.COM>
Date: 26 Oct 89 17:38:41 GMT
References: <327@ssp1.idca.tds.philips.nl> <4420015@hpihoah.HP.COM>
Sender: news@sun.Eng.Sun.COM
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>You could define an architectural figure of merit as Specmark/Clock freq.

The joy of making a definition is that it is by construction true.
Completely divoirced from reality, but true.

	"It is common, for example, to find papers reporting benchmark
	results as if they were an objective measure of processor
	comparison. The experimenter in this case is varying the
	architecture, implementation, clock rates, bus width,
	technology, system structure, system software and compilers. A
	single element, the benchmark is fixed..."

Tredennick in Microprocessor Report 1989

>This seems to clearly show the advantage of RISC over 68K type machines.  I
>think it also seems to show the disadvantage of register windows, since
>PRISM, MIPS, and PA don't have them and SPARC and 88K have them.

According to my Moto handout 88K has a total of 32 registers, used for
both FP and integer units (as opposed to SPARC and MIPS with split
register utilization). No windows.

Attempting to define a single figure of merit to compare _systems_
which is meaningful is hard. Attempting to use a single figure of
merit to judge architecture is futile.

Register windows may be good, bad or indifferent ... the SPEC _times_
don't provide a experimental proof one way or the other. All of these
systems have different memory systems (thus bandwidth to memory),
implementation features (cycles per FP multiply for example), etc. 



Keith H. Bierman    |*My thoughts are my own. !! kbierman@sun.com
It's Not My Fault   |	MTS --Only my work belongs to Sun* 
I Voted for Bill &  | Advanced Languages/Floating Point Group            
Opus                | "When the going gets Weird .. the Weird turn PRO"

"There is NO defense against the attack of the KILLER MICROS!"
			Eugene Brooks