gs_neighbour.f90 File Reference

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Data Types
type	gs_neighbour::gs_neighbour_t
	Gather-scatter communication using an MPI neighbourhood collective. The whole halo exchange is carried out by a single MPI_Ineighbor_alltoallv over a distributed-graph communicator built once from the send/recv peer lists. Compared to the point-to-point gs_mpi_t this trades N Isend/Irecv pairs for one collective call: a single entry into the (serialised, on Fugaku) MPI runtime, leaving the library free to stripe the transfers across all network interfaces internally. More...

Modules
module	gs_neighbour
	Defines gather-scatter communication using MPI neighbourhood collectives.

Functions/Subroutines
subroutine	gs_neighbour::gs_neighbour_init (this, send_pe, recv_pe)
	Initialise the neighbourhood-collective communication method See gs_comm.f90 for details.
subroutine	gs_neighbour::gs_neighbour_free (this)
	Deallocate the neighbourhood-collective communication method.
subroutine	gs_neighbour::gs_nbsend_neighbour (this, u, n, tag, deps, strm)
	Pack the send buffer and initiate the neighbourhood collective. The collective covers both directions, so all of the communication is launched here; gs_nbrecv_neighbour is a no-op.
subroutine	gs_neighbour::gs_nbrecv_neighbour (this, tag)
	No-op: the neighbourhood collective issued in nbsend handles both the send and receive directions, so there is nothing to pre-post here.
subroutine	gs_neighbour::gs_nbwait_neighbour (this, u, n, op, strm)
	Wait for the neighbourhood collective and reduce the received slabs.
subroutine	gs_neighbour::gs_nbsend_vec_neighbour (this, u, n, nc, tag, deps, strm)
	Pack the nc components and launch a single neighbourhood collective.
subroutine	gs_neighbour::gs_nbrecv_vec_neighbour (this, tag, nc)
	No-op: the collective is launched in nbsend_vec.
subroutine	gs_neighbour::gs_nbwait_vec_neighbour (this, u, n, nc, op, strm)
	Wait for the vector collective and reduce each received slab into u. Peer i's received slab holds nc consecutive blocks of recvcounts(i) values, matching the sender's packing convention.