Path: utzoo!mnetor!uunet!lll-winken!lll-lcc!pyramid!prls!mips!mash
From: mash@mips.COM (John Mashey)
Newsgroups: comp.arch
Subject: Re: sun's new mips honesty (16.67/14 = 8.4/x, solve for x)
Message-ID: <1503@winchester.mips.COM>
Date: 5 Feb 88 03:12:49 GMT
References: <168@eos.UUCP>
Reply-To: mash@winchester.UUCP (John Mashey)
Organization: MIPS Computer Systems, Sunnyvale, CA
Lines: 39

In article <168@eos.UUCP> jaw@eos.UUCP (James A. Woods) writes:
># "there's only one two." -- local tv station slogan

>sun touts the new 4/110 as doing seven vax integer mips
>in the second paragraph of their press release.
>makes real sense this time, given the clock rate.

>taking 8.4 as the mashey-measured mips for the 4/280
>unix utility run (guess they finally have the compiler tuned),
>we get an honest 7 coming out of the equation
>(clock rate 16.67 mhz -> 14 mhz).

>it still doesn't make the *current* high-end 4/200 series
>machine an honest ten, so they must be reserving the verity
>of this figure for a future (cypress chip) member of the line ...

I'm sure James meant some more :-) in his discussion.  To correct a
possible misimpression, the "MIPS UNIX" utility run James referenced
was indeed 8.4, from "MIPS Update for 3.0, Dec 87".  However, as it states:
"# VAX 11/780 runs 4.3BSD for MIPS UNIX, Ultrix 2.0 (vcc) for
Stanford, VAX/VMS for all others.  Use of 4.3BSD (no global optimizer)
probably inflates the MIPS UNIX column by about 10%."

In any case, as I'm sure James knows quite well:
	a) A mips-claim without realistic backup benchmarks is not
	tremendously meaningful.
	b) A clock rate scaling is at best a gross estimate, ESPECIALLY
	for heavily-cached RISC machines.  From the data given, one doesn't
	know whether or not there's a cache, and if so, how big it is.
	Likewise, it's conceivable that going to a slower clock, and a
	different memory system design, might shave clocks off the
	memory-to-cache latency, so that a 14MHz design might be faster
	that 14/16.7 of the 16.7MHz design.

Presumably everyone may know more when benchmark numbers are available.
-- 
-john mashey	DISCLAIMER: <generic disclaimer, I speak for me only, etc>
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