Replies to post #11192 on Advanced Micro Devices Inc (AMD)

[jhalada]

kpf,

And then, assuming PGI Compilers indeed lower SPEC-scores, why did IBM use it for Spec reports?

Because PGI compiler generated 64 bit code.

(Yes I remember it was me who posted about lukewarm commitment.... and on playing games around Opterons).

I am not sure it is the right conclusion. If IBM is pushing AMD64 bit code, I think it is more of an endorsement than if they used x86 code.

Besides, IBM is pushing Linux, so 32 bit code from Intel compiler under Windows would seem a little irrelevant.

Joe

[Haddock]

And then, assuming PGI Compilers indeed lower SPEC-scores

I think that's a pretty safe assumption. If you keep the rest of the system constant including the compiler then 64 bit code is faster than 32 bit code on average. See AMD's gcc-based SPEC benchmarks for the 244.

Noone seems to run SPEC as fast as the Intel compiler. That may change (it seems the others are improving faster right now), but right now the others are also-rans in terms of sheer execution speed.

why did IBM use it for Spec reports?

If you are buying an Opteron for high performance (scientific) computing then it could well be in order to run 64 bit Fortran90 code. Gcc can't do that and neither can the Intel compilers (for different reasons), so you have to use PGC.

If you have a particular problem that fits in 32 bits you can use the Intel compiler and get marginally better performance. Note that the Intel compiler is available for Linux too.

If your program is in Fortran77 or C or C++ then you also have the option of using gcc either 32 or 64 bits. Usually the 64 bit version is faster.

There's really no reason to suspect IBM's motives on this one. A lot of their HPC customers will use PGC Fortran - it's a reasonable thing to benchmark.