[Users] Possible performance issue with some codes

[Frank Loeffler]

Hi,

On Thu, Aug 18, 2011 at 12:04:45AM +0200, Ian Hinder wrote:
> For any code which does not use the
> ADMBase::[lapse/shift]evolution_method parameters to control their
> evolution, unnecessary syncs will be performed for the ADMBase
> variables.  Whereas before these parameters seemed to be a superfluous
> part of the ADMBase infrastructure (after all, why activate your
> evolution thorn if you're not going to evolve with it?), it now seems
> that it is essential to extend and use these parameters if you want to
> use ADMBase, or performance will suffer.  The GT evolution code would
> suffer from this, the last time I looked at it, and other groups'
> codes might also. 

I didn't think of that, right. I see two possible solutions: either do
use the ADMBase parameters in all evolution thorns (you don't really
have to use them - extend the parameter and set it to that in the
parameter file - I know, that's ugly but it works); or we provide these
syncs in an extra thorn or via a new parameter within ADMBase. Both
approaches are not ideal imho. The ideal would be if each evolution
thorn would actually use these parameters, but that is arguably a lot to
request.
Or, wouldn't the following work: evolution_method has 'none' and
'static' as meaning 'no evolution is done'. We could use 'none' for
nothing at all is done and 'static' for real "static evolutions" with
'none' being the default. However, this would require 'none' being also
provided for the other *_evolution_method parameters.

Frank

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