Bad Performance on Power4/AIX

jschmidt jochenc... at googlemail.com
Tue Oct 30 09:20:05 UTC 2007


Hi Axel,

thanks for your answer. I'm running interactively on one frame (I'm
only granted acces to this frame when running in interactive mode).
Since the sopt version is Ok, I don't expect that there is a problem
with the memory. If I run the parallel version with 1 processor, I
expect a similar (or at least not much different) behaviour than what
I find in serial. Is this correct? In my case, the parallel with 1
processor is about a factor of 100 slower than the serial version,
although I'm running on the same machine.

I'll keep trying, but this is very suprising to me, because I've never
had such a problem on an opteron cluster.

Regards,
Jochen


On 29 Okt., 21:56, Axel <akoh... at gmail.com> wrote:
> On Oct 29, 9:28 am, jschmidt <jochenc... at googlemail.com> wrote:
>
> > Hi,
>
> > I've just compiled CP2K on a system with Power4-processors
> > ("Regatta"), running under AIX, and there is a problem with the
> > parallel version. The sdbg and sopt is fine, but as soon as I switch
> > to pdbg or popt (using the arch-files from the cvs) the timings are
> > really bad. A system with one water molecule needs about 100 secs
>
> hi,
>
> have you checked that a) you are not running across multiple
> regatta frames (=> network overload) or b) you actually have
> requested and been granted access to multiple cpus to run in
> parallel on and c) have enough memory to not run into permanent
> swapping/paging. the latter would easily explain a 100x increase
> in runtime.
>
> cheers,
>     axel.
>
> for
>
> > initialization and again about 100 secs per MD step. Using the sopt-
> > version this is only about 1 sec. Here is the arch-file that I used:
>
> > PERL     = perl
> > CC       = cc
> > CPP      = /usr/ccs/lib/cpp
> > FC       = mpxlf95_r -qsuffix=f=f90
> > LD       = mpxlf95_r
> > AR       = ar -r
> > DFLAGS   = -D__AIX -D__ESSL -D__FFTSG -D__FFTESSL\
> >            -D__parallel -D__BLACS -D__SCALAPACK
> > CPPFLAGS = -C $(DFLAGS) -P
> > FCFLAGS  = -C -g -q32 -qarch=pwr4 -qflttrap=overflow:zerodivide:enable
> > \
> >            -qfullpath -qinitauto=FF -qnointlog -qnosave -qsigtrap -
> > qtune=pwr4
> > LDFLAGS  = $(FCFLAGS) -bnoquiet
> > LIBS     = -L /afs/ipp/@sys/lib -lscalapack\
> >            /afs/ipp/@sys/lib/blacsF77init_MPI-POWER4-0.a\
> >            /afs/ipp/@sys/lib/blacs_MPI-POWER4-0.a -lessl\
> >           -L/afs/rzg/@sys/lib -llapack-essl -lessl -lpessl -lmass -
> > lhmd
>
> > OBJECTS_ARCHITECTURE = machine_aix.o
>
> > Is anyone using the latest cvs-version on a such a system?
>
> > Thanks for your help!
> > Jochen




More information about the CP2K-user mailing list