Message-ID: <Pine.LNX.4.61.0512142252550.19087@gannet.stats>
Date: 2005-12-14T23:02:04Z
From: Brian Ripley
Subject: 32 vs 64 bit
In-Reply-To: <43A09CD4.3020803@bank-banque-canada.ca>
On Wed, 14 Dec 2005, Paul Gilbert wrote:
> I ran R on an AMD Athlon 64 with a 32 bit Linux (by accident, I moved
> the hard disk from another machine). Now, after install 64 bit Linux and
> 64 bit R, I am finding some of my R tests are quite a bit slower, I
> think because memory demands cause a lot of swap. Does anyone know if
> extra memory usage would be mainly because of R itself, or is there a
> lot of extra memory demand because of the OS, windowing system, and
> other apps?
There's a definite effect from R itself.
I never run a machine without plenty of RAM for everyday tasks but if you
did, that could have a bigger effect on a 64-bit OS as all the
applications are larger. (My 64-bit Opteron desktop has 2Gb, for example,
whereas its 32-bit predecessor had 1Gb.)
This _is_ discussed in the R-admin manual (section 7 in R 2.2.0 in the
version I just looked at). You can run 32-bit R on 64-bit Linux if you
want for speed (and I sometimes do): this too is discussed in the manual.
--
Brian D. Ripley, ripley at stats.ox.ac.uk
Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/
University of Oxford, Tel: +44 1865 272861 (self)
1 South Parks Road, +44 1865 272866 (PA)
Oxford OX1 3TG, UK Fax: +44 1865 272595