[MITgcm-devel] missing barrier causing problems for packing

[Patrick Heimbach]

Hi there,

top of CTRL_PACK should be fine.
It's not seen by TAF, so explicit MPI call is ok.

Cheers
p.

On Jan 30, 2012, at 10:12 PM, Jean-Michel Campin wrote:

> Hi Matt,
> 
> I don't feel qualified to answer your question. 
> Patrick, please, help !
> 
> Cheers,
> Jean-Michel
> 
> On Mon, Jan 30, 2012 at 04:20:09PM -0800, Matthew Mazloff wrote:
>> Hi Jean-Michel
>> 
>> Yes, an MPI_BARRIER call, thanks for clarifying.
>> 
>> And at the top of CTRL_PACK would be a great place for it.  Would it
>> be ok for me to check this in -- does anyone have any objections?
>> 
>> An alternative fix would be to pack the ctrls first, then the
>> gradients.....
>> 
>> let me know, thanks
>> -Matt
>> 
>> 
>> 
>> 
>> 
>> On Jan 30, 2012, at 4:05 PM, Jean-Michel Campin wrote:
>> 
>>> 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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>>> 
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>> 
>> 
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Patrick Heimbach | heimbach at mit.edu | http://www.mit.edu/~heimbach
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