Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!nrl-cmf!ames!oliveb!intelca!clif
From: clif@intelca.intel.com (Ken Shoemaker)
Newsgroups: comp.arch
Subject: Re: i860 Dhrystones
Summary: Correction to i860 CPU benchmarks
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Keywords: i860 N10 Floating Point Dhrystones
Message-ID: <210@intelca.intel.com>
Date: 13 Mar 89 21:39:47 GMT
References: <654@cimcor.mn.org> <93088@sun.uucp> <701@pcrat.UUCP> <93452@sun.uucp> <15074@winchester.mips.COM>
Organization: Intel Corp., Santa Clara, Ca.
Lines: 40

In article <15074@winchester.mips.COM>, mash@mips.COM (John Mashey) writes:
> In article <93452@sun.uucp> garner@sun.UUCP (Robert Garner) writes:
> .....
> >The judgement so far is that the 22% improvement must be coming from
> >the FORTRAN version.  As I've never seen a FORTRAN version of 

Mashey writes
> 
> If it is indeed true that this is no typo, it is fascinating,
> as it is well-known that C's byte-by-byte copy can add 25-30% over
> (for example) PASCAL, or anything that has fixed-length character strings.
> (On an R3000, 34% of Dhrystone is in strcmp & strcpy.)
> In reading the Intel i860(TM) performacne document, it is interesting
> to note that 7 benchmarks are presented:
> Dhrystone 1.1 and 2.1, Stanford Integer, SP & DP Whetstone,
> and FORTRAN and Coded LINPACK.
> 
> That means, that in terms of published benchmarks that seem apples-to-apples
> comparable, the sum total is:  SP & DP Whetstone.

The i860 CPU benchmark report had a TYPO the Dhrystone benchmark used
the Greenhill C compiler not FORTRAN.
Sorry to dissappoint everyone who thought that we were getting great
Dhrystone numbers by rewritting the benchmark in FORTRAN.

As for the simulated numbers versus actual numbers.  We have an excellent
correlation (within 3%) between simulated numbers and actual numbers.

My speculation (note the word speculation) as to why the the Dhrystone 
numbers are so good is: 

	Clock Frequency
	128-bit loads for string instructions
	The clocks/instruction is 1 (I imagine other RISC chips
	approach 1 clock/instruction but don't actually obtain it)

Clif Purkiser
Intel Corp.

The above views are mine and don't represent Intel's official position.