/* -*- Mode: C; c-basic-offset:4 ; indent-tabs-mode:nil ; -*- */
/*
* (C) 2017 by Argonne National Laboratory.
* See COPYRIGHT in top-level directory.
*/
#include "mpiimpl.h"
/* Algorithm: Batched Sendrecv
*
* Send/recv to permuted destinations/sources, in batches based on Tony Ladd's
* suggestion. Permuting the sources helps to avoid overloading a single source
* or destination all at once.
*
* We use this as our medium-sized-message algorithm.
*/
#undef FUNCNAME
#define FUNCNAME MPIR_Ialltoall_sched_intra_permuted_sendrecv
#undef FCNAME
#define FCNAME MPL_QUOTE(FUNCNAME)
int MPIR_Ialltoall_sched_intra_permuted_sendrecv(const void *sendbuf, int sendcount,
MPI_Datatype sendtype, void *recvbuf,
int recvcount, MPI_Datatype recvtype,
MPIR_Comm * comm_ptr, MPIR_Sched_t s)
{
int mpi_errno = MPI_SUCCESS;
int i;
int rank, comm_size;
int ii, ss, bblock, dst;
MPI_Aint sendtype_extent, recvtype_extent;
#ifdef HAVE_ERROR_CHECKING
MPIR_Assert(sendbuf != MPI_IN_PLACE); /* we do not handle in-place */
#endif
comm_size = comm_ptr->local_size;
rank = comm_ptr->rank;
MPIR_Datatype_get_extent_macro(sendtype, sendtype_extent);
MPIR_Datatype_get_extent_macro(recvtype, recvtype_extent);
bblock = MPIR_CVAR_ALLTOALL_THROTTLE;
if (bblock == 0)
bblock = comm_size;
for (ii = 0; ii < comm_size; ii += bblock) {
ss = comm_size - ii < bblock ? comm_size - ii : bblock;
/* do the communication -- post ss sends and receives: */
for (i = 0; i < ss; i++) {
dst = (rank + i + ii) % comm_size;
mpi_errno = MPIR_Sched_recv(((char *) recvbuf + dst * recvcount * recvtype_extent),
recvcount, recvtype, dst, comm_ptr, s);
if (mpi_errno)
MPIR_ERR_POP(mpi_errno);
}
for (i = 0; i < ss; i++) {
dst = (rank - i - ii + comm_size) % comm_size;
mpi_errno = MPIR_Sched_send(((char *) sendbuf + dst * sendcount * sendtype_extent),
sendcount, sendtype, dst, comm_ptr, s);
if (mpi_errno)
MPIR_ERR_POP(mpi_errno);
}
/* force the (2*ss) sends/recvs above to complete before posting additional ops */
MPIR_SCHED_BARRIER(s);
}
fn_exit:
return mpi_errno;
fn_fail:
goto fn_exit;
}