Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!csd4.milw.wisc.edu!cs.utexas.edu!uunet!cs.dal.ca!iotek!garyb
From: garyb@iotek.UUCP (Gary Burrell)
Newsgroups: comp.arch
Subject: Re: Info on DSP chips
Message-ID: <344@venus.iotek.UUCP>
Date: 1 Aug 89 11:54:59 GMT
References: <337@venus.iotek.UUCP> <23379@winchester.mips.COM> <277@melair.UUCP> <3469@epimass.EPI.COM>
Reply-To: garyb@venus.UUCP (Gary Burrell)
Organization: IOTEK Inc
Lines: 51

In article <3469@epimass.EPI.COM> jbuck@epimass.EPI.COM (Joe Buck) writes:
>In article <277@melair.UUCP> low@melair.UUCP (Rick Low) writes:
>>..., then I wrote a 1024-point, radix-4,
>>complex, floating-point (obviously), looped (i.e. not inline coded)
>>FFT for this beast. [ the TI TMS320C30 ].
>>
>>I simulated this FFT using TI's C30 simulator and assuming zero wait
>>states for external memory.  This FFT ran in 2.71 ms for an average
>>of about 17 MFLOPs.  The control structure of this FFT -- i.e. non-butterfly
>>code -- took 18 percent of the total execution time.
>
>I'm currently working on the real thing, not just the simulator.
>
>Unless you took account of a bug in the C30 simulator, your number is
>a bit too optimistic: it always takes two cycles to write to external
>memory, even with zero wait states; the C30 simulator counts it as one.
>To get the true time, add a cycle for each external memory write cycle.
>

	This is one reason why I was questioning the original results
in the afterword of DSP micro Dec 88.  They were comparing estimated
(not even simulated) data to real world benchmarks on super computers
and comming up with some amazing results.  (est 20 MFLOPS Single Prec.
Linpack for the TMS320C30).

	IMHO one should not compare estimated, simulated and real data
as estimation and simulation often err on the side of optimism.

	I repeat my challange can anyone show me 20 MFLOPS SP LINPACK
on a real TMS320C30 system, or must I continue to be a Doubting
Gary about this chip being able to perform that well.

	I'm not disputing this is a great DSP chip but what I am
saying is that the estimations seem to me to be too optimistic, and I
want some "REAL NUMBERS" before I will accept this estimate.  Any TI
applications Engineers ready to take up the challenge :-)

		
		Doubting

			  Gary

			<<<<<<******>>>>>>
Gary R. Burrell, Iotek Inc,     |*| E-Mail: garyb@iotek.uucp	|*| 
1127 Barrington St., Suite 100, |*| Fax:    (902)420-0674	|*|   
Halifax, N.S., B3H 2P8, Canada  |*| Phone:  (902)420-1890	|*| 

Damm it Jim 
  I'm a Doctor not a Computer Scientist!
              
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