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Re: Atlas libs and lsode?

From: Christoph Spiel
Subject: Re: Atlas libs and lsode?
Date: Wed, 24 Oct 2001 17:33:00 +0200
User-agent: Mutt/1.2.5i

On Wed, Oct 24, 2001 at 03:05:51PM +0200, Douglas Eck wrote:
> I loaded the atlas libraries specifically
> compiled for debian. They sped up general
> matrix ops drastically, both in dynamically
> linked progs and in regular .m files.  The
> speedup is drastic... 10x.
> However, they slightly slow down calls to
> lsode.  The slowdown is much less drastic, on
> the order of 10% but it's there. I'm wondering
> why this is and if I can fix it such that
> lsode is faster.

I wonder whether your ATLAS libraries are linked
dynamically, too.  ELF libraries need an extra
register to hold the code's offsets.  On
register-starved archs like the ia32 this is
known to degrade performance up to 5% or so.

The recommendation would be to try with a
static ATLAS library that is compiled with
g++-2.95.x (with later g++s ATLAS' performance
drops markedly).


Christoph L. Spiel  <address@hidden>
Hammersmith Consulting,  web:
Phone: +49-8022-662908, fax: +49-8022-662909

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