I am running some linear algebra functions in Mathematica on different CPUs. I've noticed a massive performance difference between Intel and AMD processors. For a certain script I wrote that uses
Eigenvalue functions several times:
Intel Xeon (2.8 GHz): 20s
Intel Core 2 Q9400 (2.6 GHz): 48s
AMD Opteron 6276 (2.3 GHz): 76s
AMD Opteron 6378 (2.4 GHz): 100s
There are many variables here. All these are running with 4 cores. However, the AMDs are launched on an HPC with access to more cores. The Intels are much faster, but I was very surprised when the faster AMD did consistently worse over several trials. Someone suggested Mathematica is using MKL, which is so optimized for Intel it causes problems for AMD.
Does anyone have any ideas for what causes this? I would also be interested in what other information or tests I should do to narrow down the possibilities.