[Rd] Running R on dual/quad Opteron machines
Thomas Lumley
tlumley at u.washington.edu
Mon Mar 6 18:13:07 CET 2006
On Mon, 6 Mar 2006, Simone Giannerini wrote:
> The environment will probably be either Unix/Linux or Solaris and the
> amount of RAM will be 8-16Gb, depending on the number of processors.
> My main concerns are the following:
>
> 1. How much does R benefit from passing from one processor to
> two/four processor machines? Consider that the typical intensive use
> of the server
> will be represented by simulation studies with many repeated loops.
The typical way that R is used on multiprocessor systems is running more
than one program, rather than parallel processing. If four people are
using the computer or if one person splits 10,000 iterations of a
simulation into 4 sets of 2,500 you will be using all four processors.
> 2. How does R cope with parallelization and/or parallelized compiled code ?
>
It doesn't really. There are interfaces to MPI and PVM and there is the
possibility of using a parallel BLAS to speed up linear algebra. These
won't help much unless the server is under fairly low load so that a
single program can use more than 100% of a single processor. Our
multiprocessor Opteron servers are rarely that underutilized.
-thomas
Thomas Lumley Assoc. Professor, Biostatistics
tlumley at u.washington.edu University of Washington, Seattle
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