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Date:      Thu, 30 Mar 2000 17:09:16 +1000
From:      "Andrew Reilly" <areilly@nsw.bigpond.net.au>
To:        "Igor B. Bykhalo" <goshik@binep.ac.ru>
Cc:        "-questions@FreeBSD" <freebsd-questions@FreeBSD.ORG>, "-stable@FreeBSD" <freebsd-stable@FreeBSD.ORG>
Subject:   Re: Doing math - need advice
Message-ID:  <20000330170916.A5632@gurney.reilly.home>
In-Reply-To: <01bf9a0e$ffb5fe00$0000e9c1@serv2.binep.ac.ru>
References:  <01bf9a0e$ffb5fe00$0000e9c1@serv2.binep.ac.ru>

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On Thu, Mar 30, 2000 at 09:12:59AM +0300, Igor B. Bykhalo wrote:
> We are going to use mathematical package
> (EPR spectra simulation). Program relies
> on BLAS, LAPACK and ARPACK libraries - all
> in Fortran 77. Program itself can be built
> using gcc, egcs or pgcc.
> 
> Questions:
> 
> 1. What is the recommended way to build
>    f77 libraries to get maximum performance?
>    Should we use g77 from 4.0-Release, or
>    we can stay on 3-Stable and use f2c + pgcc
>    (from ports)?

cd /usr/ports/math/blas; make install
cd /usr/ports/math/lapack....

> 2. Does anyone know incarnations of the mentioned
>    libraries in C language?

There's a clapack on netlib.org, so there's probably a c blas
behind that somewhere.  Dunno about ARPACK.

> 3. Where to read some general advices on the optimization
>    of math perfomance (under FreeBSD)? :)

There are a few generic pentium optimisation pages on the
network.  These may or may not be relevant to P6 based machines.

Up to a certain level of performance, and for many code
structures, memory system behaviour, and therefore data layout
and access will dominate the application performance.  You're
therefore best served by getting things right, and studying
locality of reference, rather than compiler optimisations.

Compiler optimisations (and even assembly language tweaking) can
come last, after some thorough profiling.  (Yes, FreeBSD supports
profiling.)

-- 
Andrew


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