[MITgcm-support] Poor cpu usage percentage

[Ryan Abernathey]

Nick,

I would humbly suggest that it is a waste of time to optimize MITgcm for a
six year old laptop. Surely at Geomar you have more powerful computing
resources available to you, for which MITgcm is well tested and optimized...

Best,
Ryan

On Mon, Jul 20, 2015 at 10:47 AM, Rogan, Nicholas <nrogan at geomar.de> wrote:

> hi Dimitris,
>
> Thanks for your patience!
>
> It appears that it is a problem with the I/O routines as there are
> significant differences in wall clocl times between the two compilations.
>
> The main routines that are time expensive are
> LOAD_FIELDS_DRIVER
> >> EXF_GETFORCING 1500s vs 300s
>
> MONITOR 1700s vs 300s
>
> and
>
> DO_THE_MODEL_IO 1900s vs 1200s
>
> There aren't really any other major differences, in fact on the whole the
> users and system times for the iMac are less than those for the macbook.
>
> Looking at the Makefiles there are the following differences:
> iMac
> -   Does not have a specified F90C compiler (The macbook pro has gfortran
> specified as F90C compiler)
>     NB The other compilers are identical between the two compilations,
> i.e. FC=gfortran, CC=gcc, LINK=gfortran
>
> FFLAGS (relative to macbook)
> -  Does not have:   -Wunused
> -  Does have      :   -f-no-second-underscore -fbacktrace
> - BOTH HAVE:   -Wunitialized -fconvert=big-endian
>
> FOPTIM
> - Does not have:   -ftree-vectorize
>
> NOOPTFLAGS
> - Does not have:   -O2 -funroll-loops
> - Does have      :   -O0
>
> LIBS
> - Does not have:   -lcurl
>
> There are also a lot of included .h files that occur in the MacBook's
> Makefile that are absent from the iMac.
>
> Any quick suggestions? I'll keep work myself  on trying to figure out the
> implications of the differences.
>
> Thanks!
>
> Nick
>
>
>
> On 20/07/15 03:02 PM, *Dimitris Menemenlis * <dmenemenlis at gmail.com>
> wrote:
>
> you mainly need to look at your fortran and c compilers and compiler
> options.
>
> On Jul 20, 2015, at 9:29 AM, Rogan, Nicholas <nrogan at geomar.de> wrote:
>
> I'm comparing the two Makefiles now, so far only different Netcdf/compiler
> locations.
>
>
> --
> Kind regards,
>
> Nick
>
> ------------------------------------------------------
> Dr Nicholas Rogan
> Postdoctoral Researcher
> *http://www.geomar.de/en/mitarbeiter/fb2/ch/nrogan/
> <http://www.geomar.de/en/mitarbeiter/fb2/ch/nrogan/>*
>
> GEOMAR Helmholtz Centre for Ocean Research, Kiel
> Wischhofstraße 1-3, Build. 12
> D-24148 Kiel
> Germany
> ------------------------------------------------------
>
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>
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