[Users] meeting minutes for 2021-04-01

[Roland Haas]

Present: Roland, Peter D, Steve, David Bradley, Erik S, Ken, Miguel G,
Zach, Maria

SPEC benchmark contribution
* Steve provided update on status
* SPEC org is proceeding ahead
* will have to check license given for code
** Cactus is LGPL (v2+)

release planning
* Roland provided an update on POWER status
* needs documenation
* will not include monitor for strain due to problems getting this to
  work with FFI due to ringing
* Zach and Maria asked about computing radiated energy. Roland reported
  that this is not currently present to keep POWER doing one thing and
  do that well. Will add how to compute energy to documenation.
* feature requests:
** energy and angular momentum
** reading in ASCII files in addition to HDF5 files
* need to start testing on important systems since we are at the 2
  months mark

making LORENE2 the default ET LORENE
* Zach reported on state from 2018 and that Josh had identified and
  issue with convergence in LORENE but that will not affect the parts
  the ET uses
* Roland to contact Bruno G. about updates
* would at that point also update included tarball

simfactory Python3 transition
* are using Python3 by default right now
* no breakage observed

tickets:
* https://bitbucket.org/einsteintoolkit/tickets/issues/2516 Zach
  suggested to try perturbing initial data to roundoff and check what
  difference is observed and if that is larger than the differences
  seen here
** general agreement that there should be not difference baring
   con2prim issues and roundoff 
** Roland would want to run a short test himself to see if any
   differences is observerd
* https://bitbucket.org/einsteintoolkit/tickets/issues/963 Peter will
  take a look but has not had time yet
* https://bitbucket.org/einsteintoolkit/tickets/issues/2407 Erik says
  he will pursue this after the next release. Roland reports that
  currently all simfactory clusters should support this but this will
  require a minimum version of gcc 6.X either to compile or as a
  libstc++ backend for the Intel compiler. Discussed how much speed
  benefit (if any) the Intel compiler provides compared to GNU
  compilers. Zach reports on benchmarks with Baikal benchmarks and
  found that GNU provided faster single core performance, but some
  other codes (eg LORENE) was much faster with Intel. Erik and Zach
  suggest a single node benchmark on a real physics setup. Peter
  mentioned extra options required to get best performance out of
  compilers in particular wrt to vectorization.

ET as a library
* Zach reported on efforts to use ET as analysis tool for black holes
  at home http://blackholesathome.net/
* meant as means to increase waveform generation throughput
* Zach could reproduce the gallery example GW150914 using 2GB of memory
  with waveforms that looks as good or better
* this will require a binary library of the ET for OSX, Linux and
  Windows
* Roland has some initial work to compile ET using the MSYS Windows
  build system (package system for mingw a small footprint variant of
  Cygwin)
* Erik reported on efforts at PI to provide material for high school
  students

Minute taker next week: Steve
Chair next weel: Peter D

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