[MITgcm-devel] GLOBAL_SUM in cost_final.F

[Jean-Michel Campin]

Hi Patrick and Martin,

Discovered that it produces some problems with OpenAD, so not
going to change this right now.

I will first make similar changes in just one small routine (dic_cost.F)
which is independant from pkg/cost & ecco_cost_final.F 
and will only break tutorial_global_oce_biogeo (OpenAD).
And then when this one is fixed will proceed with the rest of the
changes.

Cheers,
Jean-Michel

On Tue, Oct 29, 2013 at 11:44:13AM -0400, Patrick Heimbach wrote:
> Hi there,
> 
> looks like option 3 is cleanest (i.e. same treatment across all packages).
> 
> Thanks for changing.
> -Patrick
> 
> On Oct 24, 2013, at 2:59 PM, Jean-Michel Campin <jmc at ocean.mit.edu> wrote:
> 
> > Hi,
> > 
> > I started to test some changes in pkg/cost/cost_final.F,
> > to replace the call to           GLOBAL_SUM_RL( fc , myThid ) 
> > with a call to    GLOBAL_SUM_TILE_RL( tile_fc , fc , myThid )
> > 
> > There is a practical advantage to do this is that I can get
> > better forward gradient agreement when using MPI compared to non-MPI
> > (when GLOBAL_SUM_SEND_RECV is defined in CPP_EEOPTIONS.h). 
> > For instance, with tutorial_tracer_adjsens, forward grad 
> > testreport with MPI will give 16 digits for forward grad 
> > whereas now it's only 5 (on baudelaire with gfortran).
> > 
> > There is also a less obvious advantage is that 
> > GLOBAL_SUM_RL( fc , myThid )
> > gives the wrong results when using multi-threads (since
> > fc is in common block).
> > 
> > I have several versions that I can check-in:
> > 1) only changes in cost_final.F (but this leave on the side
> > few other cost contributions.
> > 2) add "tile_fc(bi,bj)" to cost.h and change
> > cost_final.F seaice_cost_final.F shelfice_cost_final.F thsice_cost_final.F
> >  (the only pkg that would need GLOBAL_SUM_RL( fc ) would be pkg/ecco)
> > 3) same as (2) + also change ecco_cost_final.F
> >  (changes are not major, total of 6 lines, changing
> >   fc = fc
> >  to
> >   tile_fc(bi,bj) = tile_fc(bi,bj)
> >  )
> > I think (3) would be cleaner (and easier to follow and check), but I don't
> > know how many different versions of ecco_cost_final.F users have.
> > 
> > Suggestions ?
> > 
> > Cheers,
> > Jean-Michel
> > 
> > _______________________________________________
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> > MITgcm-devel at mitgcm.org
> > http://mitgcm.org/mailman/listinfo/mitgcm-devel
> 
> 
> ---
> Patrick Heimbach | heimbach at mit.edu | http://www.mit.edu/~heimbach
> MIT | EAPS 54-1420 | 77 Massachusetts Ave | Cambridge MA 02139 USA
> FON +1-617-253-5259 | FAX +1-617-253-4464 | SKYPE patrick.heimbach
> 



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