[Beowulf] Intel 64bit (emt) Fortran code and AMD Opteron
kus at free.net
Fri Oct 29 08:55:26 PDT 2004
In message from Greg Lindahl <lindahl at pathscale.com> (Thu, 28 Oct 2004
>On Thu, Oct 28, 2004 at 01:39:52PM -0600, Craig Tierney wrote:
>> However, for most applications the vectorization
>> is going to give you the big win.
>People think that, but did you know that SIMD vectorization doesn't
>help any of the codes in SPECfp?
It's interesting !
Opteron SPECfp2000 results obtained w/help of PGI 5.1-3 includes
-fastsse copmiler option. SPECfp2000 results (for Opteron) based
on old ifc 7.0 compiler include options like -xW which allow
to create SIMD instructions. Etc. There is 2 possibilities
a) These compilers didn't generate SSE2-containing codes for any
program from SPECfp2000 - what looks strange for me
b) In the case we'll re-translate the source of SPECfp2000
w/suppression of SSE commands generation, performance results will be
the same. Do I understand you correctly, that you say about case b) ?
BTW, if I remember correctly, ATLAS dgemm codes for Opteron are better
if they are using SIMD fp operations - but of course, it's "out of
> Remember that the Opteron can use
>both fp pipes with scalar code. This is very different from the
Yes, but 32-bit ifc compilers (which don't know about Opteron
microarchitecture) gave better results than pgi compilers oriented
to "right" microarchitecture. Of course, I don't say about yours
PathScale compilers which usually are the best (in the perofrmance
of codes generated) but too expensive :-( .
Zelinsky Institute of Organic Chemistry
>I'd say this myth is the #1 myth in the HPC industry right
More information about the Beowulf