[OMPI users] 2 to 1 oversubscription

[Robert Kubrick]

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