Re: [bgl-discuss] Comparison between BGL nodes and standard PPCs

[Donald Sinclair <dks@xxxxxxxxxxx>]

No, I don't get any help from the 440d. For the code I am using I only
get about 200 Mflops/CPU. I have other versions of the code I might try.
The version I am currently using was one optimized for the Pentium 4/Xeon
architecture, to allow the compilers I use on those machines to generate
SSE/SSE2 instructions. However, I am not working too hard on trying to
optimize BGL code until there is more guidance, and evidence that the
compiler is really tuned to this particular architecture. It is only
with this version of the compiler that the 440d option produces working
code. With the previous version the 440d option produced garbage.
                                     Don

On Thu, 10 Mar 2005, Steven Pieper wrote:

> Don,
> 
>   Do you get any benifit from 440d?  I get none or even a slow down.  In
> a typical case this leaves me with only 265 MFLOPS/processor (using just
> qarch=440, but O5, etc) compared to 429 on seaborg.  I'm told that the
> next version of the compiler might be better.
> 
> steve
> 
> >>> What are the major differences other than the presence of communication
> >>> hardware between the BGL processors and other Power PC chips, Power 3, for
> >>> example? I ask, since despite the fact that both this chip and the
> >>> Power 3 have 2 floating point units and the rest of the unit has the
> >>> Power PC architecture, and I use the same compiler (xlf), the performance
> >>> I get from the 700 MHz BGL processor is less than half what I can get from
> >>> a 375 MHz Power 3, even when I use the -qarch=440d.
> >>>                                    Don Sinclair
> >>> 
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