Hi Robert,
I ran some very crude tests and found that things slowed down once you
got over 8 cores at a time. However, they didn't slow down by 50% if
you went to 16 processes. Sadly, the tests were so crude, I did not
keep good notes (it appears).
I'm running a gcm, so my benchmarks may not be very useful to most
folks. If there was an easy-to-compile benhmark that I could run on
my cluster, I'd be curious what the results are too.
Thanks, Jody
On 11-Jul-09, at 2:16 PM, Robert Kubrick wrote:
The Open MPI FAQ recommends not to oversubscribe the available cores
for best performances, but is this still true? The new Nehalem
processors are built to run 2 threads on each core. On a 8 sockets
systems, that sums up to 128 threads that Intel claims can be run
without significant performance degradation. I guess the last word
is to those who have tried to run some benchmarks and applications
on the new Intel processors. Any experience to share?
http://www.open-mpi.org/faq/?category=running#oversubscribing
http://en.wikipedia.org/wiki/Simultaneous_multithreading
http://communities.intel.com/community/openportit/server/blog/2009/06/11/nehalem-ex-brings-new-economics-to-scalable-systems
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