/* -*- Mode: C; c-basic-offset:4 ; indent-tabs-mode:nil ; -*- */
/*
*
* (C) 2001 by Argonne National Laboratory.
* See COPYRIGHT in top-level directory.
*/
#include "mpiimpl.h"
/*
* Recursive-doubling
*
* We use a lgp recursive doubling algorithm. The basic algorithm is
* given below. (You can replace "+" with any other scan operator.)
* The result is stored in recvbuf.
*
* .vb
* recvbuf = sendbuf;
* partial_scan = sendbuf;
* mask = 0x1;
* while (mask < size) {
* dst = rank^mask;
* if (dst < size) {
* send partial_scan to dst;
* recv from dst into tmp_buf;
* if (rank > dst) {
* partial_scan = tmp_buf + partial_scan;
* recvbuf = tmp_buf + recvbuf;
* }
* else {
* if (op is commutative)
* partial_scan = tmp_buf + partial_scan;
* else {
* tmp_buf = partial_scan + tmp_buf;
* partial_scan = tmp_buf;
* }
* }
* }
* mask <<= 1;
* }
* .ve
*
*/
#undef FUNCNAME
#define FUNCNAME MPIR_Scan_intra_recursive_doubling
#undef FCNAME
#define FCNAME MPL_QUOTE(FUNCNAME)
int MPIR_Scan_intra_recursive_doubling(const void *sendbuf,
void *recvbuf,
int count,
MPI_Datatype datatype,
MPI_Op op, MPIR_Comm * comm_ptr, MPIR_Errflag_t * errflag)
{
MPI_Status status;
int rank, comm_size;
int mpi_errno = MPI_SUCCESS;
int mpi_errno_ret = MPI_SUCCESS;
int mask, dst, is_commutative;
MPI_Aint true_extent, true_lb, extent;
void *partial_scan, *tmp_buf;
MPIR_CHKLMEM_DECL(2);
if (count == 0)
return MPI_SUCCESS;
comm_size = comm_ptr->local_size;
rank = comm_ptr->rank;
/* set op_errno to 0. stored in perthread structure */
{
MPIR_Per_thread_t *per_thread = NULL;
int err = 0;
MPID_THREADPRIV_KEY_GET_ADDR(MPIR_ThreadInfo.isThreaded, MPIR_Per_thread_key,
MPIR_Per_thread, per_thread, &err);
MPIR_Assert(err == 0);
per_thread->op_errno = 0;
}
is_commutative = MPIR_Op_is_commutative(op);
/* need to allocate temporary buffer to store partial scan */
MPIR_Type_get_true_extent_impl(datatype, &true_lb, &true_extent);
MPIR_Datatype_get_extent_macro(datatype, extent);
MPIR_CHKLMEM_MALLOC(partial_scan, void *, count * (MPL_MAX(extent, true_extent)), mpi_errno,
"partial_scan", MPL_MEM_BUFFER);
/* This eventually gets malloc()ed as a temp buffer, not added to
* any user buffers */
MPIR_Ensure_Aint_fits_in_pointer(count * MPL_MAX(extent, true_extent));
/* adjust for potential negative lower bound in datatype */
partial_scan = (void *) ((char *) partial_scan - true_lb);
/* need to allocate temporary buffer to store incoming data */
MPIR_CHKLMEM_MALLOC(tmp_buf, void *, count * (MPL_MAX(extent, true_extent)), mpi_errno,
"tmp_buf", MPL_MEM_BUFFER);
/* adjust for potential negative lower bound in datatype */
tmp_buf = (void *) ((char *) tmp_buf - true_lb);
/* Since this is an inclusive scan, copy local contribution into
* recvbuf. */
if (sendbuf != MPI_IN_PLACE) {
mpi_errno = MPIR_Localcopy(sendbuf, count, datatype, recvbuf, count, datatype);
if (mpi_errno)
MPIR_ERR_POP(mpi_errno);
}
if (sendbuf != MPI_IN_PLACE)
mpi_errno = MPIR_Localcopy(sendbuf, count, datatype, partial_scan, count, datatype);
else
mpi_errno = MPIR_Localcopy(recvbuf, count, datatype, partial_scan, count, datatype);
if (mpi_errno)
MPIR_ERR_POP(mpi_errno);
mask = 0x1;
while (mask < comm_size) {
dst = rank ^ mask;
if (dst < comm_size) {
/* Send partial_scan to dst. Recv into tmp_buf */
mpi_errno = MPIC_Sendrecv(partial_scan, count, datatype,
dst, MPIR_SCAN_TAG, tmp_buf,
count, datatype, dst,
MPIR_SCAN_TAG, comm_ptr, &status, errflag);
if (mpi_errno) {
/* for communication errors, just record the error but continue */
*errflag =
MPIX_ERR_PROC_FAILED ==
MPIR_ERR_GET_CLASS(mpi_errno) ? MPIR_ERR_PROC_FAILED : MPIR_ERR_OTHER;
MPIR_ERR_SET(mpi_errno, *errflag, "**fail");
MPIR_ERR_ADD(mpi_errno_ret, mpi_errno);
}
if (rank > dst) {
mpi_errno = MPIR_Reduce_local(tmp_buf, partial_scan, count, datatype, op);
if (mpi_errno)
MPIR_ERR_POP(mpi_errno);
mpi_errno = MPIR_Reduce_local(tmp_buf, recvbuf, count, datatype, op);
if (mpi_errno)
MPIR_ERR_POP(mpi_errno);
} else {
if (is_commutative) {
mpi_errno = MPIR_Reduce_local(tmp_buf, partial_scan, count, datatype, op);
if (mpi_errno)
MPIR_ERR_POP(mpi_errno);
} else {
mpi_errno = MPIR_Reduce_local(partial_scan, tmp_buf, count, datatype, op);
if (mpi_errno)
MPIR_ERR_POP(mpi_errno);
mpi_errno = MPIR_Localcopy(tmp_buf, count, datatype,
partial_scan, count, datatype);
if (mpi_errno)
MPIR_ERR_POP(mpi_errno);
}
}
}
mask <<= 1;
}
{
MPIR_Per_thread_t *per_thread = NULL;
int err = 0;
MPID_THREADPRIV_KEY_GET_ADDR(MPIR_ThreadInfo.isThreaded, MPIR_Per_thread_key,
MPIR_Per_thread, per_thread, &err);
MPIR_Assert(err == 0);
if (per_thread->op_errno) {
mpi_errno = per_thread->op_errno;
if (mpi_errno)
MPIR_ERR_POP(mpi_errno);
}
}
fn_exit:
MPIR_CHKLMEM_FREEALL();
if (mpi_errno_ret)
mpi_errno = mpi_errno_ret;
else if (*errflag != MPIR_ERR_NONE)
MPIR_ERR_SET(mpi_errno, *errflag, "**coll_fail");
return mpi_errno;
fn_fail:
goto fn_exit;
}