[Carpet] expensive logging of CarpetRegrid[2] parameter changes

[Thomas Radke]

Hi,

CarpetRegrid[2] provides steerable parameters as an interface for other 
thorns to change the grid structure. I just found out that those 
parameters are steered rather frequently which then may cause problems 
when runtime parameter changes are to be logged (eg. as thorn Formaline 
can do): logging every individual parameter change becomes 
runtime-expensive, and the logfile may grow to unreasonable sizes.

As a measure to prevent this situation, we could exlude changes for some 
parameters from being logged. I believe this is not a very good solution 
though.
Instead we should think about changing the way how thorns can interact 
with CarpetRegrid[2]. Maybe they could communicate via grid variables 
instead of steerable parameters ?

-- 
Cheers, Thomas.