> This would be true of 64-bit builds of R, not 64-bit CPUs.
> [...]
> This doesn't mean that a 32-bit build of R on a 64-bit processor will be
> slower than a 32-bit build of R on a 32-bit processor.
There is the issue, however, of running a 32bit application on a 64bit
OS. Under RedHat and SuSE this works transparently and I've not
noticed a performance issue, but under Debian's or Ubuntu's chroot
setup there is in my experience a measurable performance hit. Of
course, one could simply run 32bit Debian along with 32bit R on an
Opteron.
Cheers,
Jas.
=======================================
Jasjeet S. Sekhon
Associate Professor
Travers Department of Political Science
Survey Research Center
UC Berkeley
http://sekhon.berkeley.edu/
V: 510-642-9974 F: 617-507-5524
=======================================
Thomas Lumley writes:
> On Wed, 5 Apr 2006, Jasjeet Singh Sekhon wrote:
>
> >
> > Hi,
> >
> > 64bit CPUs, such as opterons, help significantly with large databases
> > or if you are running multiple processes. But there is a speed
> > penalty if you are not.
>
> This would be true of 64-bit builds of R, not 64-bit CPUs.
>
> On a 64-bit processor you can usually run either 64-bit or 32-bit builds
> of R, and the 64-bit one will be able to access more memory but will be
> slower.
>
> This doesn't mean that a 32-bit build of R on a 64-bit processor will be
> slower than a 32-bit build of R on a 32-bit processor.
>
> -thomas
>
> Thomas Lumley Assoc. Professor, Biostatistics
> [EMAIL PROTECTED] University of Washington, Seattle
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