[gmx-users] fftw tweaking ?

Marc Baaden baaden at smplinux.de
Thu Oct 10 16:13:50 CEST 2002


I was checking on tweaking the fftw libraries for particular processor types.
I couldn't verify if that topic came up already, as the search functiun on
ww.gromacs.org it seems to be currently dysfunctional (probably a transition
problem, Erik ?).

I was pointed at this by the existence of a package p4fftwgel2 in Debian, the
description of which says:

Library for computing Fast Fourier Transforms on Intel P4

 This library computes Fast Fourier Transforms (FFT) in one
 or more dimensions. It is extremely fast. This package
 contains the documentation and the shared version of the
 libraries. To get the static library and the header files you
 need to install p4fftwgel-dev.
 This library uses the same interface as fftw so should be a drop-in
 replacement, but is currently limited to single precision only.
 The code is tuned for Intel P4 processors and can be as much as three
 times as fast as vanilla fftw.

Has anybody tried that ? Is it relevant for Gromacs performance ?
(I guess it would only be needed for mdrun+pme, or maybe some analysis

I haven't managed to compile Gromacs with it yet, probably because some
things don't have the right name (eg fftw.h instead of sfftw.h ..), but
I have to check.

Any suggestions wellcome.

BTW there are also tweaked packages for AMD K6-2 and K7 processors.

 Dr. Marc Baaden - Laboratory of Molecular Biophysics, Oxford University
 mailto:baaden at smplinux.de  - ICQ# 11466242 -  http://www.marc-baaden.de
 FAX/Voice +49 697912 39550  -  Tel: +44 1865 275380  or  +33 609 843217

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