April 22 2024

Carl, Evan, Gabriel, Hugo, Jan, Marc, Matthew, Nicole

Note-taker

Carl, Gabriel, Jan, Evan, Hugo, Joseph

We are at kokkos/kokkos-comm
- Cédric and Carl are maintainers: contact them if you'd like to see changes at the repository level
Discussions ongoing in the "discussions" tab/feature
- Discuss longer-form topics, questions and ideas there (e.g. instead of/before opening an issue)
"MPI" in the project name?
- Matthew: no MPI in the name
- Carl opened a discussion about it so everyone can discuss their take on the name

Application Use Cases
- Carl is working on thin MPI wrappers in Impl namespace
Modern C++ / MPI
- Senders/Receivers: pika and HPX libraries can support MPI in their reference implementation (see related paper: latestest revision of P2300 proposal from WG21/C++ standards committee)
  - Try to experiment with MPI + pika/HPX
- Error handling: exceptions? std::expected?
- Talks to revive the discussion on C++ MPI API the MPI forum side
Accelerator-Initiated Communication / Support
- Evan & Nicole: looking into NCCL and NVIDIA/mpi-acx, add support for acceleration-initiated communications in kokkos-comm (work over the summer)
Smart NICs
- Talk from Richard Graham (NVIDIA) on the topic next Friday, April 26: CEA/NNSA Seminar Series
Performance optimization (new working group/subject of interest starting today)
- Jan: Benchmark the current version of kokkos-comm to have a baseline.
- Jan: how do we treat corner cases, optimize memory usage, etc...? Look into strategies for exchanging non-contiguous data: MPI_Datatypes? multiple communications? pack/unpack? Look into serialization
- Jan: working on callback-registration API for MPI
- Evan is interested in the topic as well

Carl
- TODO: Reserve a room for Sandians
- Working on more thin MPI wrappers
- Improve unit testing
Evan
- Working with Nicole for now
Gabriel
- Submitted a PR adding support for Ready and Synchronous mode send operations (both blocking & immediate): pending approval, feedback and reviews are welcome!
- Discussion on initialization of kokkos-comm: use MPI Sessions? See this paper on why it may be interesting performance-wise for our use cases
Jan
- kokkos-remote-spaces: provides a distributed View
  - Hopefully releasing v2.0 this month
  - Intel developing SHMEM for this project
  - More consistent support of subviews
Hugo
- Nothing to add, but feel free to ask any MPI-related questions
Marc
- Nothing to add
Matthew
- Interested in discussing why "MPI" should not appear in the name. Feel free to ask any MPI-related questions as well
Nicole
- Looking into MPI and Kokkos for working on device-initiated communications over the summer (starting mid-May at SNL)