[R] xeon processor and ATLAS

Uwe Ligges ligges at statistik.uni-dortmund.de
Wed Aug 29 17:16:56 CEST 2007

hui xie wrote:
> Thanks very much for all your advice. To be clear, my OS is window
> XP. I bought this server last year. It's Dell Precision PWS690. THe
> processor is Xeon(TM) CPU 3GHZ, 2G RAM. I am not sure how to check
> more details of processor on my computer. But I went to Dell website
> and from what I can recall, it seemed that I ordered a Dual-core
> Intel Xeon 5160 3GHz, 1333FSB, 4MB L2 Cache, 80watts.
> I think from time to time, I will need linear algebra to do things
> such as Choleskey Factorization, and matrix inverse etc... At the
> same time, I considered myself quite unskilled on building R by
> myself. It seems there were lots of details that I can get things
> wrong. So if there is an existing ATLAS one on R website that I can
> use, I would be very happy to use it to replace the default one. The
> reason why I would like to use ATLAS is that R FAQ said :
> "The savings can be appreciable: on a 2.6GHz P4 and a 1000 x 1000
> matrix svd took 16.2 sec with the standard BLAS and 7.8 sec with
> ATLAS.  Because ATLAS is tuned to a particular chip we can't use it
> generally: the optimal routines for a P4 or an Athlon XP are quite
> different and neither will run at all on a PII."
> This seems to me an impressive gain to use the correct ATLAS instead
> of the default BLAS.  I guess my  Xeon processor is either a P4 or
> Core2Duo, but I am really not sure which one to use. Could you please
> offer me some suggestions?

As a Google search tells you, the Xeon 5100 series is Core2 based while 
5000 and former CPUs were NetBurst based.

Uwe Ligges

> Again, many thanks for all your advice!
> Best,
> Hui
> Uwe Ligges <ligges at statistik.uni-dortmund.de> wrote:
> Prof Brian Ripley wrote:
>> On Tue, 28 Aug 2007, hui xie wrote:
>>> hi everyone:
>>> I have a Dell Server that has a Xeon processor, and I would like
>>> to use the best ATLAS posted in the R website. I find that R has
>>> ATLAS for core2duo and P4. I am not sure which one of these two
>>> is best suited for Xeon processor, or is that neither of these
>>> two is good and I should stick with the default one that was
>>> installed originally?
>> And your OS is?
>> There are many different 'Xeon' processors with very different 
>> capabilities.
> ... the earlier similar to P4 and some similar to Core2Duo. You won't
>  make use of bigger L2/L3 caches in Xeon processors.
>> You really ought to build ATLAS for yourself if numerical linear
>> algebra performance matters to you (and it makes little difference
>>  to most people: I think Uwe Ligges quoted 10% for testing all CRAN
>>  packages).
> Right, it depends on what you are really doing. If most time is spend
> in certain numerical matrix operations, ATLAS is your friend. In all
> other cases, it does not matter so much, as Brian cited correctly.
> Uwe Ligges
>>> Your advice is very much appreciated!
>>> Best,
>>> Hui
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