[Dune] DUNE running out of memory on 65536 cores?

[Eike Mueller]

Ok, excellent, this works now, which means I can run with 65536 cores on 
Hector. Solving a problem with 3.4E10 degrees of freedom takes just over 
90 seconds if I use CG preconditioned with AMG (SSOR smoother).

I'm using the default settings, but could not quite figure out how many 
smoothing steps will be carried out. Is there a way of making sure I 
only do one SSOR step?

Thanks again,

Eike

Markus Blatt wrote:
> Hi,
> 
> On Wed, Mar 21, 2012 at 09:50:04AM +0000, Eike Mueller wrote:
>> I now tried it again with the latest version of the trunk (I use
>> revision 1542) of dune-istl, but it still fails with the same error
>> message (running out of memory) if I run the code on 65536 cores.
>>
> 
> I just took another look on my code on Blue Gene. You have to provide
>  -DAMG_REPART_ON_COMM_GRAPH in the CPPFLAGS. Using this flag the graph
>  that we partition is much smaller (one vertex per core).
> 
> Of course this will only help if the memory problem occurs within ANG:
> 
> Markus
>