Instead of broadcasting all interpolated point data to every MPI rank,
the new overload sends each point only to the one rank that needs it
for integration, reducing communication volume by ~nprocs times.
The consumer rank is computed deterministically using the same Nmin/Nmax
work distribution formula used by surface_integral callers. Two active
call sites (surf_Wave and surf_MassPAng with MPI_COMM_WORLD) now use
the new overload. Other callers (ShellPatch, Comm_here variants, etc.)
remain unchanged.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
The two MPI_Allreduce calls (data + weight) were the #1 hotspot at 38.5%
CPU time. Since all ranks traverse the same block list and agree on point
ownership, we replace the global reduction with targeted MPI_Bcast from
each owner rank. This also eliminates the weight array/Allreduce entirely,
removes redundant heap allocations (shellf, weight, DH, llb, uub), and
writes interpolation results directly into the output buffer.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
