[Carpetx-developers] Meeting Minutes – February 6, 2025

Jay Kalinani jaykalinani at gmail.com
Thu Feb 6 13:57:30 CST 2025


*Meeting Minutes – February 6, 2025*
Present: Erik, Lucas, Roland, Liwei, Zach, Steve, Swapnil, Jay, Helvi, Allen
------------------------------
Liwei:

   -

   Comparing performance between Carpet and CarpetX.
   -

   Findings:
   -

      One refinement level test shows similar speeds.
      -

      With six levels, CarpetX is about 20% slower (with and without
      subcycling).
      -

      Removing additional synchronization calls for interprocess boundaries
      (ghost-zones) and keeping sync calls only for prolongation during the
      substep makes the speed comparable to Carpet.
      -

      Further optimizations are in progress.
      -

   Erik’s suggestion: Introduce a new grid point type to track prolongation
   boundaries and set a flag to check if they are synced.
   -

   Another potential issue: Using the PointDesc object (p.I) in CarpetX
   causes minor slowdowns compared to accessing indices in Carpet.
   -

   Erik’s input: The compiler should optimize this; Liwei will share an
   example .o file for Erik to analyze.

Roland:

   -

   Z4c requires a test case.
   -

   Currently working on it and may seek Steve’s review later.

Lucas:

   -

   Testing hybrid Runge-Kutta integrators with BBH simulations.
   -

   Successfully set up a multipatch system with two puncture data and
   extracted multipole data.
   -

   May need assistance with Z4c.
   -

   Updating the robust stability test parfile and will open a PR.
   Currently experimenting with different boundary conditions.
   -

   Reviewing PRs for NewRadX in SpacetimeX and CarpetX repositories.
   -

   Zach’s question: Any tests beyond scalar wave for multipatch?
   -

      Lucas is working on a BBH test case and aims for completion before
      the May release.
      -

   Helvi’s question: Status of multipatch implementation in CanudaX?
   -

      Lucas is still working on it.
      -

   Liwei’s question: Can the multipatch code be used directly?
   -

      Lucas explained that evolution codes must be modified to compute
      derivatives and project them onto the multipatch system.
      -

      Suggests adding an option to enable/disable multipatch rather than
      maintaining two code versions.

------------------------------
Next Meeting:

Thursday, February 13, 2025 @ 10 AM CDT / 11 AM EST
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