Re: Performance again

[Herwin Jan Steehouwer <herwinjs palet nl>]

On Sun, 3 Jan 1999, geerten kuiper wrote:

> Herwin Jan,
> 
> Some ideas:
> 
> - as always, much depends on what your program is trying to do.
> - make shure you use the improved math libraries (I think
> <http://people.frankfurt.netsurf.de/Joachim.Wesner/libffm.0.28.tar.gz>
> has the latest.)
> - David Mosberger once wrote an article on optimizing code for Alpha. You
> may be able to find it somewhere on the web. Cache optimization is the main
> thing to realize the Alphas full potential.

i cannot find him ;-( also his e-mail adres i found, was not working ;(

> - using 64 bit floats will probably be almost as fast as 32 bits (contrary
> to your PentiumII, where it will be much slower.)

ok, will try that !

> - on some older Alpha boxes, memory bandwith limits performance. On your XL
> this should be less of an issue (is it 128 or 256 bits wide ?)

366Xl is 128 bits wide !

a test programm ( see attachment ) will give this output ! how can i speed
this up ?? ( gcc -o preftest preftest.c ) NO optimizing for this test ! 

SGI 100 Mhz R4k:
        time perftest i
        7.359
        time perftest f
        3.534
        time perftest d
        4.942

Alpha 233 Mhz:
        time perftest i
        9.140
        time perftest f
        2.290u
        time perftest d
        3.050u

Intel P2 300Mhz:
        time perftest i
        1.955
        time perftest f
        1.555
        time perftest d
        2.614


tanx
HJ

Herwin Jan Steehouwer
  herwinjs@palet.nl                 http://www.caiw.nl/~herwinjs
  steehouwer@kde.org              KDE developer http://www.kde.org