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Re: Itanium2@900MHz slower than alpha@666MHz ?

Thanks, I'll forward the message to that list. Can't check for dmesg
right now because I started some benchmarks from www.fftw.org and I
don't want to 'disturb'. I mainly want to see if I can reproduce their

However, this is well tested code and it's been running on the alpha for
months. Had there been any FP error, it would have crashed on the spot.


On Mon, Oct 20, 2003 at 04:33:41PM -0700, David Mosberger wrote:
> This probably won't answer your question, but you may be better off
> asking such questions on linux-ia64@vger.kernel.org (since it's
> unlikely to be related to Debian itself).  In general, you'll want to
> watch out for non-finite arithmetic (including denormal arithmetic),
> but since you're comparing it to Alpha, that's probably not likely the
> source of the problem.  Just to be on the safe side, you may want to
> double-check the output of dmesg.  If you're getting lots of fpswa
> traps, then denormal arithmetic may be the issue.  Compiling with -ftz
> might help then (it will cause denormals to get flushed to zero and
> hence you'd have the fpswa trap, at the cost of some loss of
> precision).
> 	--david
> >>>>> On Tue, 21 Oct 2003 01:01:46 +0200, Ionut Georgescu <george@physik.tu-cottbus.de> said:
>   Ionut> Hi, I am puzzled about the speed of a zx2000 workstation with
>   Ionut> a 900Mhz CPU.  According to the SPECfp2000 benchmarks, this
>   Ionut> workstation should be about twice as fast as a DS10 alpha
>   Ionut> workstation.
>   Ionut> The test program is only doing some Fourier transforms
>   Ionut> (fftw2) and some matrix multiplications. Both fftw2 and the
>   Ionut> program have been compiled with ecc -O2 -ipo -limf. ecc is
>   Ionut> Version 7.1, Build 20030307.
>   Ionut> With or without optimization, the program runs about 25%
>   Ionut> slower on the zx2000. Are there any compiler related issues ?
>   Ionut> The specfp numbers were all obtained with ecc 6.0, which I
>   Ionut> don't have.
>   Ionut> Both the alpha and the Itanium2 run Debian stable and kernel
>   Ionut> 2.4.20.
> -- 
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* Ionut Georgescu
* http://www.physik.tu-cottbus.de/~george/
* Registered Linux User #244479
* "In Windows you can do everything Microsoft wants you to do; in Unix you
*                can do anything the computer is able to do."

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