[ET Trac] [Einstein Toolkit] #666: have CarpetIOScalar output grid scalar directly rather than applying reductions to them

[Einstein Toolkit]

#666: have CarpetIOScalar output grid scalar directly rather than applying
reductions to them
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  Reporter:  rhaas        |       Owner:  eschnett
      Type:  enhancement  |      Status:  review  
  Priority:  minor        |   Milestone:          
 Component:  Carpet       |     Version:          
Resolution:               |    Keywords:          
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Comment (by rhaas):

 I aggree with all statemnets. I don't think that I can remove the MPI
 communication without changing more lines in CarpetReduce (essentially
 making the "origin" reduction a special case). This is one of the reasons
 why I did not propose it initially :-) Right now one can simply abuse eg.
 the 'maximum' reduction to get timeseries output for scalars that are
 identical on all processors (also without saving on MPI communication, but
 since this happens at IO time, I was less concerned about and MPI call).

 No, I don't really want to add a fake reduction. Hence the originally
 proposed the change to how CarpetIOScalar works which admittedly was not
 that much better. :-)

 Yes, the best thing is likely to modify CarpetIOASCII. If you have time to
 look into it that would be highly appreciated. Please let me know if you
 need help to test/debug it (I could also give it a try but that will take
 a while).

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Ticket URL: <https://trac.einsteintoolkit.org/ticket/666#comment:5>
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