[CentOS] maximum cpus/cores in CentOS 4.1

Joshua Baker-LePain jlb17 at duke.edu
Thu Sep 8 18:40:38 UTC 2005

On Thu, 8 Sep 2005 at 11:33am, Bryan J. Smith wrote

> Peter Arremann <loony at loonybin.org> wrote:

> > less memory bandwidth for each cpu and so on.
> Okay, this is _misleading_.  You're thinking Intel SMP.
> Opterons _always_ have 128-bit of DDR (2 channels) per CPU.
> Opteron uses NUMA (and HyperTransport partial meshes for
> CPU-I/O).  There is _no_ "less memory bandwidth for each
> cpu".  That is a trait of Intel SMP [A]GTL+, not AMD
> NUMA/HyperTransport.
> Yes, if the Opteron has to access memory over on another CPU,
> then that is a performance issue.  If the other CPU is on
> another mainboard, then yes, contention can happen there.

One has to be even more careful with terminology these days.  You can see 
less memory bandwidth per *core* with dual core Opterons.  But, as you 
point out, each CPU (socket -- what should we call it?) has, essentially, 
its own bank of memory.

Joshua Baker-LePain
Department of Biomedical Engineering
Duke University

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