[MITgcm-devel] missing barrier causing problems for packing

[Jean-Michel Campin]

Hi Matt,

Just to clarify a detail: you mean an MPI_BARRIER call 
(the usual _BARRIER just sync threads and does not do anything
between different MPI procs).

There is an example of such a call in ini_procs.F
(the one in eeboot_minimal.F is not the right one)

And as where to put it, may be (naively) at the top of S/R CTRL_PACK ?

Cheers,
Jean-Michel

On Mon, Jan 30, 2012 at 02:13:19PM -0800, Matthew Mazloff wrote:
> Hello
> 
> We have come across the problem where the packing initiates before
> all processors finish writing adxx_theta, and thus sometimes
> ecco_cost is incorrect (zeros were read/written instead of proper
> gradients.)
> 
> We need to have a barrier put in either
> 
> around line 261 at the beginning of the_main_loop.F before
> CALL INITIALISE_VARIA( mythid )
> 
> or in the_model_main.F  around line 600 between
>       CALL THE_MAIN_LOOP( myCurrentTime, myCurrentIter, myThid )
> and
>          CALL CTRL_PACK( .FALSE. , mythid )
> 
> 
> Let me know what is preferable -- and if someone wants to go ahead
> and check this in that would be great!
> 
> Thanks
> Matt
> 
> 
> 
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