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? Paul Gilbert
32 vs 64 bit
3 messages · Paul Gilbert, Brian Ripley, Roger D. Peng
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
When we first moved to 64 bit I found that certain things were slower. I believe it is because of the increased overhead for memory management. -roger
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? Paul Gilbert
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Roger D. Peng | http://www.biostat.jhsph.edu/~rpeng/