2023.01.12 Meeting Notes

Tentative Agenda

• Individual/group updates
• OpenMP parallelism (outer inner)
• Nested parallelism
• Status of face centered fields
• Support for Ascent
• Check stale branches
• non-WIP PRs

Individual/group updates

JD/LR

• working on downstream codes discovering "interesting" Parthenon behavior
  • "packing by list" could become "expensive" for 2D problems (with little data), but not really relevant for 3D sims
  • call vec.size() rather than caching size
  • creating variable labels by creating new string rather than using cached ones
  • will be easy to fix (simple tuning for infrastructure calls)
• working combining sending "null" data multiple sparse vars between blocks
  • originally sending quite a lot of messages
  • coalescing sometimes helped (but strongly dependent on MPI lib)

BP

• working on getting KHAMRA from diverged "forward" (LANL) branch to develop (100 commits behind and ahead)
• redesign KHAMRA to subclass packages
  • what about the "refinement" packages. Is it useful at this place or out of place?
  • will write a spec ("Parthenon Enhancement Proposal") to discuss

JM

• started implementing experimental DG method on top of Parthenon
• big Q: how to translate DG "language" to Parthenon vocabulary

FG

• working on AthenaPK shakedown tests
• updated coords class merged
• looking at options to change primitive prolongation

PM

• got access to Polaris for INCITE

JS

• working on LB in AthenaK for AMR

PG

• fixed Crusher/Frontier configuration (PR ready for review)
• updated AthenaPK and parthenon-hydro to run on Crusher/Frontier
• started WIP to fix compiler warnings in the entire code base

OpenMP parallelism (outer inner)/Nested parallelism

• JD discovered really bad performance OpenMP at some point but seem to behave predictable (and as expected) right now
• Packing of blocks has impact on performance in combination with environment variables on OpenMP thread placement

Status of face centered fields

• JD will cleanup "CC->Var" PR as soon as feasible as other works depend on it (and it's 95ish% done)

Support for Ascent

• should be optional dependency
• can this be done as a package?
• -> implement minimal version for now and update/separate later incrementally

Next meeting Feb 2