A simple try assisted with GPT : nonblocking gather/scatter exchanges

[mystic-qaq]

PR.md

[Copilot]

Pull request overview

Refactors PW_Basis::gatherp_scatters and PW_Basis::gathers_scatterp from blocking MPI_Alltoallv to non-blocking MPI_Irecv/MPI_Isend exchanges with overlapping pack/unpack work, adds a per-instance reusable communication workspace, and introduces a round-trip unit test.

Changes:

• Replace MPI_Alltoallv with non-blocking sends/receives plus MPI_Waitsome-driven unpack overlap in both gather/scatter directions, separating send/receive into distinct workspace slices.
• Add acquire_comm_workbuf<T>() returning per-instance mutable std::vector storage (float and double specializations) and add fine-grained timer regions.
• Add test_comm_roundtrip.cpp (round-trip equality and a zero-plane "stress" layout sweep) and register it in the test CMakeLists.txt.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
source/source_basis/module_pw/pw_gatherscatter.h	Rewrites both routines to use Irecv/Isend with manual self-copy, dedicated send/recv workspace, and overlapped unpack via MPI_Waitsome.
source/source_basis/module_pw/pw_basis.h	Declares acquire_comm_workbuf plus mutable per-instance buffers; adds <vector> include.
source/source_basis/module_pw/test/test_comm_roundtrip.cpp	New round-trip tests using a friend accessor subclass to call the protected gather/scatter methods.
source/source_basis/module_pw/test/CMakeLists.txt	Registers the new test source file.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.