[gmx-developers] Benchmark Errors & 3.2.0 Performace Loss

[Josh Hursey]

Erik,
In our PPC environment [Cairo cluster], we are running Yellow Dog Linux 3.0 and compiling the code with GNU's gcc Version 3.3 
configured with the following flags:
/usr/src/rpm/BUILD/gcc-3.3-20030414/configure
--prefix=/usr
--mandir=/usr/share/man
--infodir=/usr/share/info
--enable-shared
--enable-threads=posix
--disable-checking
--with-system-zlib
--enable-__cxa_atexit
--enable-altivec
--disable-libgcj
--host=ppc-yellowdog-linux

GROMACS has been configured with the --enable-ppc-altivec flag enabled in both instances. We used the same compilers for both 
installations.
If you would be interested in the ./configuration output for both installs here are some further links:
3.1.5
-----
http://cluster.earlham.edu/cairo/software/gromacs-3.1.5_pre1-Altivec-and-Sqrt/config.log
3.2.0
-----
http://cluster.earlham.edu/cairo/software/gromacs-3.2.0_beta1-Optimal/config.log

I am not exactly sure what you are looking for when you refer to the breakdown of the flopcount reports. All of the GROMACS 
log files should be in those directories that I pointed to in my earlier mail message. I can run a concise comparison between 
them if you let me know what you want to look at.

Thanks,
Josh

=============================================
Erik Lindahl wrote on Wed, 3 Mar 2004 00:33:38 +0100:
> Subject: Re: [gmx-developers] Benchmark Errors & 3.2.0 Performace Loss
> 
> Hi Josh,
> 
> Thanks, this is a lot of useful stuff that I'll try to digest in a week 
> or two.
> 
> The performance loss does sound a bit strange, though - the innerloops 
> haven't changed at all apart from the Athlon fix, and that part I've 
> benchmarked very carefully. Could you look in your logfile and check
> 
> 1. If you are using SSE/Altivec inner loops
> 2. The breakdown of the flopcount reports
> 3. If you are using the same compilers in both cases
> 
> Whatever you do, stay away from the IBM compilers on OS X for now; they 
> are still incredibly buggy for Altivec code.
> 
> Cheers,
> 
> Erik
> 
> 
> 
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