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Re: False alarm (Re: reshape slowdown?)
From: |
mavram |
Subject: |
Re: False alarm (Re: reshape slowdown?) |
Date: |
Wed, 23 Feb 2005 13:07:38 +0200 |
User-agent: |
Mutt/1.5.5.1+cvs20040105i |
On Wed, Feb 23, 2005 at 09:03:19AM +0100, Francesco Potorti` wrote:
> >On Athlon MP 2000 MHz:
> >
> >octave:3> s=rand(3000);
> >octave:4> tic; a=s'; toc
> >ans = 1.9846
> >
> >On Athlon XP 1666 MHz -> 0.9 second.
>
> >I know what is the problem now. I do not know how to solve it.
> >The problem is that when running in SMP mode the task is bouncing between
> >two CPUs flushing the caches. That can be verified booting in UP mode.
> >So on my system in UP mode:
> >
> >octave:1> a=rand(3000);
> >octave:2> tic; b=a'; toc
> >ans = 0.80099
> >
> >Which is 3 times faster!
>
> This is awfully slow with respect to what I would (wrongly?) expect. On
> my very old Pentium II 350 MHz, I get:
>
> octave> s=rand(3000);
> octave> tic; a=s'; toc
> ans = 2.6762
> octave> version
> ans = 2.1.64
>
> using the latest Debian package. Why is my box only three times as slow
> as an Athlon 2000 on matrix transpose?
>
> --
> Francesco Potortì (ricercatore) Voice: +39 050 315 3058 (op.2111)
> ISTI - Area della ricerca CNR Fax: +39 050 313 8091
> via G. Moruzzi 1, I-56124 Pisa Email: address@hidden
> Web: http://fly.isti.cnr.it/ Key: fly.isti.cnr.it/public.key
>
>
>
> -------------------------------------------------------------
> Octave is freely available under the terms of the GNU GPL.
>
> Octave's home on the web: http://www.octave.org
> How to fund new projects: http://www.octave.org/funding.html
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> -------------------------------------------------------------
>
After reading your mails, I cheched the timing on my box (Celeron
600 MHz with 320 Mbyte RAM/Debian 3.1 testing, kernel 2.4,
Octave 2.1.57).
s=rand(3000);
tic, s'; toc
ans = 8.18339100014418 !!!
Is this the normal difference between the two distibutions or
something is utterly wrong with my computer/operation system
installation/octave installation ?
-------------------------------------------------------------
Octave is freely available under the terms of the GNU GPL.
Octave's home on the web: http://www.octave.org
How to fund new projects: http://www.octave.org/funding.html
Subscription information: http://www.octave.org/archive.html
-------------------------------------------------------------
- reshape slowdown?, Dmitri A. Sergatskov, 2005/02/21
- Re: reshape slowdown?, David Bateman, 2005/02/22
- Re: reshape slowdown?, John W. Eaton, 2005/02/22
- False alarm (Re: reshape slowdown?), Dmitri A. Sergatskov, 2005/02/22
- False alarm (Re: reshape slowdown?), John W. Eaton, 2005/02/22
- Re: False alarm (Re: reshape slowdown?), Dmitri A. Sergatskov, 2005/02/22
- Re: False alarm (Re: reshape slowdown?), Francesco Potorti`, 2005/02/23
- Re: False alarm (Re: reshape slowdown?),
mavram <=
- Re: False alarm (Re: reshape slowdown?), Paul Kienzle, 2005/02/23
- Re: False alarm (Re: reshape slowdown?), Dmitri A. Sergatskov, 2005/02/25
- Re: False alarm (Re: reshape slowdown?), John W. Eaton, 2005/02/23