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

[Andrew Siegel <siegela@xxxxxxxxxxx>]

did we upgrade compiler at some point?

On Thu, 10 Mar 2005, Donald Sinclair wrote:

> 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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> 
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> 

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