[R] R on AMD64 (Opteron)

[Jerome Asselin]

----- Original Message ----- 
From: "Liaw, Andy" <andy_liaw at merck.com>
To: "'Prof Brian Ripley'" <ripley at stats.ox.ac.uk>; "Jose Quesada"
<quesada at gmail.com>
Cc: <r-help at stat.math.ethz.ch>
Sent: Monday, July 26, 2004 9:18 AM
Subject: RE: [R] R on AMD64 (Opteron)


> Just one more thing for folks intending to try Opterons with >1 cpu:
You'll
> probably want to use a NUMA kernel, rather than a SMP one.
>
> Cheers,
> Andy

Thanks for the advice, but is there another reason why you write this beside
a large (I mean >8) number of CPUs?

At http://lse.sourceforge.net/numa/faq/ I read,

What is the difference between NUMA and SMP?
The NUMA architecture was designed to surpass the scalability limits of the
SMP architecture. With SMP, which stands for Symmetric Multi-Processing, all
memory access are posted to the same shared memory bus. This works fine for
a relatively small number of CPUs, but the problem with the shared bus
appears when you have dozens, even hundreds, of CPUs competing for access to
the shared memory bus. NUMA alleviates these bottlenecks by limiting the
number of CPUs on any one memory bus, and connecting the various nodes by
means of a high speed interconnect.