[R] Xeon CPU and ATLAS

[Prof Brian Ripley]

AFAIK all P4s are SSE2.

He wants a Windows ATLAS build, and that is not hard, but you have to do 
that under Cygwin not MinGW.

We have a Xeon, but have found Athlons and now Opterons better value.
I don't have access to Windows Xeon machine: anyone who does could 
contribute a Xeon version of Rblas.dll (to Uwe Ligges, please).

Note that for 1.9.0 you can use Goto's BLAS and he as a P4 version that 
is faster than ATLAS (under Windows).  So I would start with that.

Although Thomas Lumley is right about cache sizes, using a P4 512kb ATLAS 
or Goto BLAS is pretty good on a Xeon (only tested by me under Linux).  
Using a BLAS for too large a cache is disastrous, but underestimating by a 
factor of 2 is not bad at all. (I think most Xeons are 1Mb cache, with 
Xeon MP being 4Mb.)

On 12 Mar 2004, Peter Dalgaard wrote:

> apjaworski at mmm.com writes:
> 
> > I am about to get a new machine at work - an IBM Intellistation with the
> > Xeon 2.8 GB processor.  It will run Windows 2000.  I would like to install
> > the proper ATLAS dll for this machine, but I am not sure if Xeon is P4?
> > Does anybody have any experience with Xeon?
> 
> Yes, we have a dual 2.8 Xeon running Linux. Very nice machine. We've
> had it for a bit more than a year and it's been of very good use. I
> can see that I did two ATLAS builds in feb 2003, one is called
> Linux_P4SSE2_2 and the other is Linux_Xeon_2. AFAIR (but it's been a
> while), the former is the preconfigured thing that came out of a
> quick-install and the other one is fully tuned version, and there was
> no difference worth speaking of between the two. 
> 
> I think the difference between P4 and Xeon is the SSE1 vs SSE2 thing,
> so you'd want the P4SSE2 DLL, but others may be able to speak more
> authoritatively. 
> 
> 

-- 
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