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

[Rebecca Neumann]

Hey Eike,

if you still want to know:
You can specify the number of smoothing steps via
Dune::Amg::Parameters params;
through the methods setNoPreSmoothSteps and setNoPostSmoothSteps.

Bye,
Rebecca

-- 
Rebecca Neumann
Universität Heidelberg
Interdisziplinäres Zentrum für Wissenschaftliches Rechnen
Im Neuenheimer Feld 368, 69120 Heidelberg
Tel: 06221/548890   Fax: 06221/548884
e-mail:<rebecca.neumann at iwr.uni-heidelberg.de>  


On 22.03.2012 11:34, Eike Mueller wrote:
> 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
>>
>
>
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