[gmx-users] Slow opterons : low Mega Flops

[David van der Spoel]

On Mon, 2005-09-12 at 14:54 -0700, Gia Maisuradze wrote:
> Thanks Erik, actually it turns out I was using gcc not ifc, now gromacs is 
> running with the expected amount of speed.
Compare your numbers to the benchmarks. For me gcc is faster than icc
8.0. Fortran is not necessary (slower) on intel/amd.
> Thanks again.
> 
> Gia
> ----- Original Message ----- 
> From: "Erik Lindahl" <lindahl at sbc.su.se>
> To: "Discussion list for GROMACS users" <gmx-users at gromacs.org>
> Sent: Monday, September 12, 2005 1:32 PM
> Subject: Re: [gmx-users] Slow opterons : low Mega Flops
> 
> 
> > Hi,
> >
> > We need details, details, details :-)
> >
> > 1. Skip MPI when it comes to basic performance testing.
> > 2. Compile FFTW 2.1.5 and Gromacs (preferrably the new release  candidate 
> > at ftp://ftp.gromacs.org/pub/beta/ ) with default options.
> > 3. Download the standard benchmarks from www.gromacs.org
> > 4. If you get results that seem to differ significantly from the ones 
> > quoted on the benchmark page, report with your CPU type and frequency 
> > here, and the exact results you get.
> >
> > Remember to say whether you are running the operating system in 32 or  64 
> > bit mode, and check the logfile whether it is using assembly loops.
> >
> > Check that you are not running other heavy jobs in the node when 
> >  testing - Gromacs defaults to nice 19 (only use idle cycles), which 
> > means it's going to yield to almost everything else. At the end of  the 
> > run you'll get a report both of the actual time, and the time  used by 
> > Gromacs.
> >
> > Cheers,
> >
> > Erik
> >
> >
> > On Sep 12, 2005, at 9:53 PM, Gia Maisuradze wrote:
> >
> >> Hi,
> >> I'm getting really slow performance on my opteron system,  performance 
> >> that is roughly half that of my old athlon mp system.   I've tried 
> >> recompiling the program with various options, mpi, no  mpi, threading, no 
> >> threading, cpu optimized, not optimized, etc.   Does anyone work with 
> >> opterons under suse 9.3 and have an idea  about what the best options for 
> >> compiling lam, fftw, and gromacs  should be?
> >>
> >> Thanks,
> >>
> >> Gia Maisuradze
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> >>
> >
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> 
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-- 
David.
________________________________________________________________________
David van der Spoel, PhD, Assoc. Prof., Molecular Biophysics group,
Dept. of Cell and Molecular Biology, Uppsala University.
Husargatan 3, Box 596,          75124 Uppsala, Sweden
phone:  46 18 471 4205          fax: 46 18 511 755
spoel at xray.bmc.uu.se    spoel at gromacs.org   http://xray.bmc.uu.se/~spoel
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