[Beowulf] Q: AMD Opteron (Barcelona) 2356 vs Intel Xeon 5460

[Mark Hahn]

>     Recently I benchmarked a Fortran based Scientific application on both
> Intel Xeon Quad core and AMD Opteron Quad core with RHEL 5. Following are
> the results:
>
>			AMD-2.3GHz	INTEL-2.33GHz
>
> 1. Serial		147.719		73.952 sec
> 2. Parallel 4 core	39.798		32.317 sec
> 3. Parallel 8 core	26.880		30.371 sec
>
>      For AMD, I used GCC compiler(gfortran), which is released by AMD for
> its barcelona-AMD fam10 based processors.

that's a tiny bit misleading - I'm certain AMD would not suggest that their 
spin of GCC is superior to a commercial AMD-tuned compiler (eg Pathscale, PGI)

I'm not sure how to understand the numbers.  it's not reasonable to expect 
AMD to be half the speed of Intel in serial.  I'd probably assume that's due 
to poor optimization; the alternative is that the code's working set fits 
in Intel's cache(s), but not in AMD's (certainly possible).  the scaling
numbers appear to support a cache-based interpretation: at 4c, the program is
as in-cache as it can be but still has mandatory misses that eventually show
AMD's memory-bandwidth advantage...