[Dune] communication problem in ALUGrid

[Markus Blatt]

Hi Arya,

On Sat, Apr 05, 2014 at 06:16:07PM +0200, Arya Fallahi wrote:
> Dear Dune,
> 
> I have since a couple of days a serious problem with communication in
> ALUGrid and I could not still solve it.

And it worked before? Weired!

> I thought probably this email list
> can be as always helpful for my problem. The problem seems to be easy but I
> could not figure out how to solve it. It is described as follows:
> 
> Suppose an element P is a ghost element in processor I and an
> InteriorBorder element in processor J. 

Mental note: As we are talking about elements, it belongs to the interior.

> In each processor there is a
> variable K corresponding to the element. The value of of K in processor I
> needs to be sent to processor J, added to K in processor J and saved
> there.
> This is what I need to do and I could not.

You have to be aware that your view might be incorrect for more than 2
processors. We do not send from one process to another one, but we
send data attached to the same entity, but present on several
processors in the correct partition, to all entities on all other
processors where the entities belong to the correct partition.

> 
> What I thought maybe correct to do is using the following parameters for
> communication function:
> 
> grid_.communicate(dataHandle,InteriorBorder_All_Interface,BackwardCommunication);
> 
> This configuration should send values from all entities to buffer and then
> write to InteriorBorder elements. Is it correct?
>

Yes.
Your are sending values attached to all entities to all other
processes where the same entities is in interior or border.

 
> I think if all entities send the values to buffer then processors I and J
> both send their K values to the buffer. Which one then is written?
> 

The order in which they are written using your data handle is not
specified. If you rely on a specific order you have to care about this
in you data handle yourself.

Markus

-- 
Do you need more support with DUNE or HPC in general? 

Dr. Markus Blatt - HPC-Simulation-Software & Services http://www.dr-blatt.de
Hans-Bunte-Str. 8-10, 69123 Heidelberg, Germany
Tel.: +49 (0) 160 97590858  Fax: +49 (0)322 1108991658 
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 836 bytes
Desc: Digital signature
URL: <https://lists.dune-project.org/pipermail/dune/attachments/20140408/2a81eaf4/attachment.sig>