[Beowulf] [gorelsky at stanford.edu: CCL:dual-core Opteron 275performance]

Jakob Oestergaard jakob at unthought.net
Wed Jul 6 07:43:00 PDT 2005

On Wed, Jul 06, 2005 at 04:12:25PM +0200, Alan Louis Scheinine wrote:
> My main point is, as I wrote, "your milage may vary."  I've heard from 
> various
> people that "everybody is going to dual-core".  I simply want to emphasize 
> that
> the dual-core choice is not for everybody.  In particular, I looked at 
> profiling

Guys, the results are very interesting - it would be very interesting to
know, too, which kernels you have been running on.

For some time there have frequently been fixes to the NUMA code in
general, and there's definitely been some changes for handling dual-core
processors in the opteron case.

If, and I don't know if this is the case, the kernels you have tested
with do not properly understand the topology of your NUMA setup in
dual-core (two processors (cores) per node (memory controller)),
performance should definitely be expected to degrade noticably.

I'm pretty sure at least 2.6.12 had NUMA/dual-core fixes in it. Anyway,
if you're running older 2.6 kernels it would probably be interesting to
try a more up-to-date kernel.

Thanks for the results and observations - it's a good read :)


 / jakob

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