[R] question about performance on different operating systems

Prof Brian Ripley ripley at stats.ox.ac.uk
Wed Dec 12 21:29:52 CET 2001

On Wed, 12 Dec 2001, Matthew Norton wrote:

> I have  a quick question for the gang.
> I'm running a batch of simulations on a number of different computers, and
> have noticed that certain systems seem to run much more slowly than others. A
> rough calculation leads me to think that R for the Macintosh is running at
> _least_ 10 times more slowly than under linux.
> To give you an idea, to run a small number of simulations takes around 80
> seconds on my laptop (running Debian linux, 200MHz processor, 112 megs RAM)
> while the same batch takes upwards of 10 minutes on a powermacintosh G4
> (350MHz and 128 megs of RAM).
> Out of curiosity, is this unexpected, or can that sort of performance hit be
> normal when changing operating systems.
> Matthew Norton
> Dept. Biological Sciences
> Universite de Montreal
> Canada.
> p.s. I'll run the same check on my windows desktop at home, and let you all
> know its speed.

In my experience R under Windows is about 10-20% slower than Linux on the
same box. We know about 5% of the difference (polling vs interrupts) and
th rest seems to be down to compiler quality (yes, they are both i686 gcc,
but still not too similar compilers often giving different answers).

A lot of this is down to the performance of the memory manager, which R
uses hard, and we had to replace on Windows at 1.2.0 not to take a big hit
(ca 3x).  Is this classic MacOS or MacOS X, and if the latter, which port?

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 272860 (secr)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

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