2023.02.02 Meeting Notes

Tentative Agenda

• Individual/group updates
• Status of face centered fields
• Parthenon Enhancement Proposal 1 -- Support Subclassing StateDescriptor, please read/skim through https://github.com/parthenon-hpc-lab/parthenon/issues/816 ahead of the sync
• Upcoming conferences (e.g., https://www.simonsfoundation.org/event/athena-workshop/ and https://www.icnsmeetings.com/conference/astronum2023/index.html)
• Next release
• non-WIP PRs

Individual/Group Updates

BP

• Opening issues
  • Many incidental, to be returned to later
  • PEP1 is current focus
• Moving kharma back to parthenon/develop

JM

• Minor bugfixes
• HPC system issues
  • Chicoma lost cuda-aware MPI. Initial results switching to host-pinned buffers suggest a ~25% performance degradation for phoebus.
  • Will collect issues on parthenon wiki

PM

• Created a test problem that helped identify a bug in communication across refinement boundaries
  • Filled ghost cells with NANs, noticed they weren't being written for beyond-first stages

LR

• Identified bug in communication across refinement boundaries
  • Boundary prolongation task gets meshblock data, that provides a meshblock pointer, that calls a refinement object, that calls a prolongation operation that itself calls base stage data. Hence higher order stages weren't being updated in ghost cells properly.
  • Looks like a first-order-in-time error but may actually be worse than that, especially if one is only calling Update in active zones
• Packing meshblocks only works for 1D fields
• Added a feature in the riot branch that allows for fewer base mesh blocks than processors (useful for AMR-intensive calculations)

BR

• Ensure that XDMF fix PR #796 eventually gets in to code
• Several immediate things to do for particles infrastructure
  • prefix sums for array indexing operations
  • remove inheritance from particle boundaries
  • particle I/O (with JM)

PG

• Contributing to Ascent support
  • Appears to be a convenient way to e.g. extract slices from data at scale
  • Usable via runtime YAML files
  • Optional external dependency
• ORNL increasing use of parthenon because it is easy to get to work
  • parthenon-hydro for student winter cluster competition
  • adding parthenon to HPC crash course

FG

• Downstream work

JS

• Working on AMR load balancing in AthenaK
  • Would be useful to compare with load balancing in parthenon because the approaches are somewhat different

Face-centered Fields

• Talk to Josh due to PR that is a current blocker
  • other block-AMR work is currently a timesink

PEP1

• General agreement that this would be a good thing
  • BP will create a PR in a week or so if there aren't objections
  • Task for BR: Think about how particles would work in this system

Conference

• Generally a good idea to coordinate parthenon-related talks to minimize repetition if multiple collaborators are at the same conference