[Beowulf] bizarre scaling behavior on a Nehalem
bill at cse.ucdavis.edu
Fri Aug 14 15:47:31 EDT 2009
Mikhail Kuzminsky wrote:
> In message from Bill Broadley <bill at cse.ucdavis.edu> (Thu, 13 Aug 2009
> 17:09:24 -0700):
> Do I unerstand correctly that this results are for 4 cores& 4 openmp
> threads ? And what is DDR3 RAM: DDR3/1066 ?
4 cores and 8 openmp threads.
4 threads is slightly faster:
Function Rate (MB/s) Avg time Min time Max time
Copy: 23670.3046 0.0135 0.0135 0.0136
Scale: 23304.9257 0.0138 0.0137 0.0139
Add: 21951.8053 0.0219 0.0219 0.0219
Triad: 21538.2451 0.0223 0.0223 0.0224
I put DDR3-1333 in the machine, but the bios seems to want to run them at
1066, I'm not sure exactly what speed they are running at.
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