[Trilinos-Users] Results from a scaling study of ML

[John Cary]

Hi All,

As promised, we have done scaling studies on the haswell nodes on Cori 
at NERSC using ML_preconditioner.exe
as compiled, so this is a weak scaling study with 65536 cells/nodes per 
processor.  We find a parallel efficiency
(speedup/expected speedup) that drops to 25% on 32 processes.

Is this expected?

Are their command line args to srun that might improve this?  (I tried 
various args to --cpu-bind.)

I can provide plenty more info (configuration line, how run, ...).

Thx.....John

On 3/24/21 9:05 AM, John Cary wrote:
>
>
> Thanks, Chris, thanks Jonathan,
>
> I have found these executables, and we are doing scaling studies now.
>
> Will report....John
>
>
>
> On 3/23/21 9:42 PM, Siefert, Christopher wrote:
>> John,
>>
>> There are some scaling examples in trilinoscouplings/examples/scaling 
>> (example_Poisson.cpp and example_Poisson2D.cpp) that use the old 
>> stack and might do what you need.
>>
>> -Chris
>
>
> On 3/23/21 7:48 PM, Hu, Jonathan wrote:
>> Hi John,
>>
>>     ML has a 2D Poisson driver in 
>> ml/examples/BasicExamples/ml_preconditioner.cpp.  The cmake target 
>> should be either "ML_preconditioner" or "ML_preconditioner.exe". 
>> There's a really similar one in ml/examples/XML/ml_XML.cpp that you 
>> can drive with an XML deck. Is this what you're after?
>>
>> Jonathan
>>
>> On 3/23/21, 5:47 PM, "Trilinos-Users on behalf of John Cary" 
>> <trilinos-users-bounces at trilinos.org on behalf of cary at colorado.edu> 
>> wrote:
>>
>>      We are still using the old stack: ML, Epetra, ...
>>
>>      When we run a simple Poisson solve on our cluster (32 
>> cores/node), we
>>      see parallel efficiency drop to 4% on one node with 32 cores.  
>> So we
>>      naturally believe we are doing something wrong.
>>
>>      Does trilinos come with a simple Poisson-solve executable that 
>> we could
>>      use to test scaling (to get around the uncertainties of our use of
>>      trilinos)?
>>
>>      Thx.......John Cary
>>
>>      _______________________________________________
>>      Trilinos-Users mailing list
>>      Trilinos-Users at trilinos.org
>> http://trilinos.org/mailman/listinfo/trilinos-users_trilinos.org
>>
>>
>>
>