[R-SIG-Mac] Does 64-bit R use multiple cores?

[Simon Urbanek]

On Nov 25, 2008, at 11:28 , John C. Tull wrote:

> I thought Altivec was a ppc-only optimization. I'm pretty sure this  
> does not apply to Intel systems, but maybe I'm wrong.
>

The Altivec part was incorrect but the multithreaded BLAS part was  
correct. Replace Altivec with your favorite three-letter code for  
Intel CPUs ;). [Not that Altivec matters in any way, since it supports  
spfp only which R doesn't use ...].

For more parallelization, see snow and pnmath by Luke Tierney.

Cheers,
S


>
> On Nov 24, 2008, at 10:23 PM, Kasper Daniel Hansen wrote:
>
>> It depends on the computations you want to do.
>>
>> R for Mac OS X uses Altivec which is a multithreaded version of  
>> BLAS and lapack. What this means is that for any computations  
>> involving matrix algebra, you do utilize multiple cores. Depending  
>> on what you are trying to compute and how that computation is  
>> implemented, this may prove to be just what you want or it may have  
>> little to no effect.
>>
>> Kasper
>>
>> On Nov 25, 2008, at 15:24 , John C. Tull wrote:
>>
>>> Dear R-mac Users:
>>>
>>> I'm wanting to leverage an 8-core Intel Mac Pro for all of its  
>>> computational glory. Looking over the mail list, it appears that  
>>> the conversation on 64-bit builds of R has been about gaining  
>>> access to memory beyond the 32-bit limit of 3.5 GB and not about  
>>> multiple processors/cores.
>>>
>>> Does running 64-bit R only take advantage of one processor core at  
>>> a time like the standard 32-bit R, or does it do symmetric  
>>> multiprocessing (is this the right terminology?). If no, is there  
>>> any possibility of doing this using X-grid or otherwise that  
>>> someone can detail? I do have 10.5 Server if I have to go down  
>>> that road.
>>>
>>> Thanks,
>>> John
>>>
>>> --
>>> John C. Tull, Ph.D.
>>> Conservation Director
>>> Nevada Wilderness Project
>>> 8550 White Fir Street
>>> Reno, NV 89523 USA
>>> 775.746.7851 (office)
>>> 775.224.2947 (mobile)
>>> www.wildnevada.org
>>>
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>>
>
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