/*
* Copyright (c) 2004-2005 The Trustees of Indiana University and Indiana
* University Research and Technology
* Corporation. All rights reserved.
* Copyright (c) 2004-2017 The University of Tennessee and The University
* of Tennessee Research Foundation. All rights
* reserved.
* Copyright (c) 2004-2005 High Performance Computing Center Stuttgart,
* University of Stuttgart. All rights reserved.
* Copyright (c) 2004-2005 The Regents of the University of California.
* All rights reserved.
* Copyright (c) 2009 University of Houston. All rights reserved.
* Copyright (c) 2013 Los Alamos National Security, LLC. All Rights
* reserved.
* Copyright (c) 2014-2016 Research Organization for Information Science
* and Technology (RIST). All rights reserved.
* $COPYRIGHT$
*
* Additional copyrights may follow
*
* $HEADER$
*/
#include "ompi_config.h"
#include "mpi.h"
#include "opal/util/bit_ops.h"
#include "ompi/constants.h"
#include "ompi/datatype/ompi_datatype.h"
#include "ompi/communicator/communicator.h"
#include "ompi/mca/coll/coll.h"
#include "ompi/mca/coll/base/coll_tags.h"
#include "ompi/mca/coll/base/coll_base_functions.h"
#include "coll_base_topo.h"
#include "coll_base_util.h"
/*
* ompi_coll_base_allgather_intra_bruck
*
* Function: allgather using O(log(N)) steps.
* Accepts: Same arguments as MPI_Allgather
* Returns: MPI_SUCCESS or error code
*
* Description: Variation to All-to-all algorithm described by Bruck et al.in
* "Efficient Algorithms for All-to-all Communications
* in Multiport Message-Passing Systems"
* Memory requirements: non-zero ranks require shift buffer to perform final
* step in the algorithm.
*
* Example on 6 nodes:
* Initialization: everyone has its own buffer at location 0 in rbuf
* This means if user specified MPI_IN_PLACE for sendbuf
* we must copy our block from recvbuf to begining!
* # 0 1 2 3 4 5
* [0] [1] [2] [3] [4] [5]
* Step 0: send message to (rank - 2^0), receive message from (rank + 2^0)
* # 0 1 2 3 4 5
* [0] [1] [2] [3] [4] [5]
* [1] [2] [3] [4] [5] [0]
* Step 1: send message to (rank - 2^1), receive message from (rank + 2^1)
* message contains all blocks from location 0 to 2^1*block size
* # 0 1 2 3 4 5
* [0] [1] [2] [3] [4] [5]
* [1] [2] [3] [4] [5] [0]
* [2] [3] [4] [5] [0] [1]
* [3] [4] [5] [0] [1] [2]
* Step 2: send message to (rank - 2^2), receive message from (rank + 2^2)
* message size is "all remaining blocks"
* # 0 1 2 3 4 5
* [0] [1] [2] [3] [4] [5]
* [1] [2] [3] [4] [5] [0]
* [2] [3] [4] [5] [0] [1]
* [3] [4] [5] [0] [1] [2]
* [4] [5] [0] [1] [2] [3]
* [5] [0] [1] [2] [3] [4]
* Finalization: Do a local shift to get data in correct place
* # 0 1 2 3 4 5
* [0] [0] [0] [0] [0] [0]
* [1] [1] [1] [1] [1] [1]
* [2] [2] [2] [2] [2] [2]
* [3] [3] [3] [3] [3] [3]
* [4] [4] [4] [4] [4] [4]
* [5] [5] [5] [5] [5] [5]
*/
int ompi_coll_base_allgather_intra_bruck(const void *sbuf, int scount,
struct ompi_datatype_t *sdtype,
void* rbuf, int rcount,
struct ompi_datatype_t *rdtype,
struct ompi_communicator_t *comm,
mca_coll_base_module_t *module)
{
int line = -1, rank, size, sendto, recvfrom, distance, blockcount, err = 0;
ptrdiff_t rlb, rext;
char *tmpsend = NULL, *tmprecv = NULL;
size = ompi_comm_size(comm);
rank = ompi_comm_rank(comm);
OPAL_OUTPUT((ompi_coll_base_framework.framework_output,
"coll:base:allgather_intra_bruck rank %d", rank));
err = ompi_datatype_get_extent (rdtype, &rlb, &rext);
if (MPI_SUCCESS != err) { line = __LINE__; goto err_hndl; }
/* Initialization step:
- if send buffer is not MPI_IN_PLACE, copy send buffer to block 0 of
receive buffer, else
- if rank r != 0, copy r^th block from receive buffer to block 0.
*/
tmprecv = (char*) rbuf;
if (MPI_IN_PLACE != sbuf) {
tmpsend = (char*) sbuf;
err = ompi_datatype_sndrcv(tmpsend, scount, sdtype, tmprecv, rcount, rdtype);
if (MPI_SUCCESS != err) { line = __LINE__; goto err_hndl; }
} else if (0 != rank) { /* non root with MPI_IN_PLACE */
tmpsend = ((char*)rbuf) + (ptrdiff_t)rank * (ptrdiff_t)rcount * rext;
err = ompi_datatype_copy_content_same_ddt(rdtype, rcount, tmprecv, tmpsend);
if (err < 0) { line = __LINE__; goto err_hndl; }
}
/* Communication step:
At every step i, rank r:
- doubles the distance
- sends message which starts at begining of rbuf and has size
(blockcount * rcount) to rank (r - distance)
- receives message of size blockcount * rcount from rank (r + distance)
at location (rbuf + distance * rcount * rext)
- blockcount doubles until last step when only the remaining data is
exchanged.
*/
blockcount = 1;
tmpsend = (char*) rbuf;
for (distance = 1; distance < size; distance<<=1) {
recvfrom = (rank + distance) % size;
sendto = (rank - distance + size) % size;
tmprecv = tmpsend + (ptrdiff_t)distance * (ptrdiff_t)rcount * rext;
if (distance <= (size >> 1)) {
blockcount = distance;
} else {
blockcount = size - distance;
}
/* Sendreceive */
err = ompi_coll_base_sendrecv(tmpsend, blockcount * rcount, rdtype,
sendto, MCA_COLL_BASE_TAG_ALLGATHER,
tmprecv, blockcount * rcount, rdtype,
recvfrom, MCA_COLL_BASE_TAG_ALLGATHER,
comm, MPI_STATUS_IGNORE, rank);
if (MPI_SUCCESS != err) { line = __LINE__; goto err_hndl; }
}
/* Finalization step:
On all nodes except 0, data needs to be shifted locally:
- create temporary shift buffer,
see discussion in coll_basic_reduce.c about the size and begining
of temporary buffer.
- copy blocks [0 .. (size - rank - 1)] from rbuf to shift buffer
- move blocks [(size - rank) .. size] from rbuf to begining of rbuf
- copy blocks from shift buffer starting at block [rank] in rbuf.
*/
if (0 != rank) {
char *free_buf = NULL, *shift_buf = NULL;
ptrdiff_t span, gap = 0;
span = opal_datatype_span(&rdtype->super, (int64_t)(size - rank) * rcount, &gap);
free_buf = (char*)calloc(span, sizeof(char));
if (NULL == free_buf) {
line = __LINE__; err = OMPI_ERR_OUT_OF_RESOURCE; goto err_hndl;
}
shift_buf = free_buf - gap;
/* 1. copy blocks [0 .. (size - rank - 1)] from rbuf to shift buffer */
err = ompi_datatype_copy_content_same_ddt(rdtype, ((ptrdiff_t)(size - rank) * (ptrdiff_t)rcount),
shift_buf, rbuf);
if (err < 0) { line = __LINE__; goto err_hndl; }
/* 2. move blocks [(size - rank) .. size] from rbuf to the begining of rbuf */
tmpsend = (char*) rbuf + (ptrdiff_t)(size - rank) * (ptrdiff_t)rcount * rext;
err = ompi_datatype_copy_content_same_ddt(rdtype, (ptrdiff_t)rank * (ptrdiff_t)rcount,
rbuf, tmpsend);
if (err < 0) { line = __LINE__; goto err_hndl; }
/* 3. copy blocks from shift buffer back to rbuf starting at block [rank]. */
tmprecv = (char*) rbuf + (ptrdiff_t)rank * (ptrdiff_t)rcount * rext;
err = ompi_datatype_copy_content_same_ddt(rdtype, (ptrdiff_t)(size - rank) * (ptrdiff_t)rcount,
tmprecv, shift_buf);
if (err < 0) { line = __LINE__; goto err_hndl; }
free(free_buf);
}
return OMPI_SUCCESS;
err_hndl:
OPAL_OUTPUT((ompi_coll_base_framework.framework_output, "%s:%4d\tError occurred %d, rank %2d",
__FILE__, line, err, rank));
(void)line; // silence compiler warning
return err;
}
/*
* ompi_coll_base_allgather_intra_recursivedoubling
*
* Function: allgather using O(log(N)) steps.
* Accepts: Same arguments as MPI_Allgather
* Returns: MPI_SUCCESS or error code
*
* Description: Recursive doubling algorithm for MPI_Allgather implementation.
* This algorithm is used in MPICH-2 for small- and medium-sized
* messages on power-of-two processes.
*
* Limitation: Current implementation only works on power-of-two number of
* processes.
* In case this algorithm is invoked on non-power-of-two
* processes, Bruck algorithm will be invoked.
*
* Memory requirements:
* No additional memory requirements beyond user-supplied buffers.
*
* Example on 4 nodes:
* Initialization: everyone has its own buffer at location rank in rbuf
* # 0 1 2 3
* [0] [ ] [ ] [ ]
* [ ] [1] [ ] [ ]
* [ ] [ ] [2] [ ]
* [ ] [ ] [ ] [3]
* Step 0: exchange data with (rank ^ 2^0)
* # 0 1 2 3
* [0] [0] [ ] [ ]
* [1] [1] [ ] [ ]
* [ ] [ ] [2] [2]
* [ ] [ ] [3] [3]
* Step 1: exchange data with (rank ^ 2^1) (if you can)
* # 0 1 2 3
* [0] [0] [0] [0]
* [1] [1] [1] [1]
* [2] [2] [2] [2]
* [3] [3] [3] [3]
*
* TODO: Modify the algorithm to work with any number of nodes.
* We can modify code to use identical implementation like MPICH-2:
* - using recursive-halving algorithm, at the end of each step,
* determine if there are nodes who did not exchange their data in that
* step, and send them appropriate messages.
*/
int
ompi_coll_base_allgather_intra_recursivedoubling(const void *sbuf, int scount,
struct ompi_datatype_t *sdtype,
void* rbuf, int rcount,
struct ompi_datatype_t *rdtype,
struct ompi_communicator_t *comm,
mca_coll_base_module_t *module)
{
int line = -1, rank, size, pow2size, err;
int remote, distance, sendblocklocation;
ptrdiff_t rlb, rext;
char *tmpsend = NULL, *tmprecv = NULL;
size = ompi_comm_size(comm);
rank = ompi_comm_rank(comm);
pow2size = opal_next_poweroftwo (size);
pow2size >>=1;
/* Current implementation only handles power-of-two number of processes.
If the function was called on non-power-of-two number of processes,
print warning and call bruck allgather algorithm with same parameters.
*/
if (pow2size != size) {
OPAL_OUTPUT((ompi_coll_base_framework.framework_output,
"coll:base:allgather_intra_recursivedoubling WARNING: non-pow-2 size %d, switching to bruck algorithm",
size));
return ompi_coll_base_allgather_intra_bruck(sbuf, scount, sdtype,
rbuf, rcount, rdtype,
comm, module);
}
OPAL_OUTPUT((ompi_coll_base_framework.framework_output,
"coll:base:allgather_intra_recursivedoubling rank %d, size %d",
rank, size));
err = ompi_datatype_get_extent (rdtype, &rlb, &rext);
if (MPI_SUCCESS != err) { line = __LINE__; goto err_hndl; }
/* Initialization step:
- if send buffer is not MPI_IN_PLACE, copy send buffer to block 0 of
receive buffer
*/
if (MPI_IN_PLACE != sbuf) {
tmpsend = (char*) sbuf;
tmprecv = (char*) rbuf + (ptrdiff_t)rank * (ptrdiff_t)rcount * rext;
err = ompi_datatype_sndrcv(tmpsend, scount, sdtype, tmprecv, rcount, rdtype);
if (MPI_SUCCESS != err) { line = __LINE__; goto err_hndl; }
}
/* Communication step:
At every step i, rank r:
- exchanges message with rank remote = (r ^ 2^i).
*/
sendblocklocation = rank;
for (distance = 0x1; distance < size; distance<<=1) {
remote = rank ^ distance;
if (rank < remote) {
tmpsend = (char*)rbuf + (ptrdiff_t)sendblocklocation * (ptrdiff_t)rcount * rext;
tmprecv = (char*)rbuf + (ptrdiff_t)(sendblocklocation + distance) * (ptrdiff_t)rcount * rext;
} else {
tmpsend = (char*)rbuf + (ptrdiff_t)sendblocklocation * (ptrdiff_t)rcount * rext;
tmprecv = (char*)rbuf + (ptrdiff_t)(sendblocklocation - distance) * (ptrdiff_t)rcount * rext;
sendblocklocation -= distance;
}
/* Sendreceive */
err = ompi_coll_base_sendrecv(tmpsend, (ptrdiff_t)distance * (ptrdiff_t)rcount, rdtype,
remote, MCA_COLL_BASE_TAG_ALLGATHER,
tmprecv, (ptrdiff_t)distance * (ptrdiff_t)rcount, rdtype,
remote, MCA_COLL_BASE_TAG_ALLGATHER,
comm, MPI_STATUS_IGNORE, rank);
if (MPI_SUCCESS != err) { line = __LINE__; goto err_hndl; }
}
return OMPI_SUCCESS;
err_hndl:
OPAL_OUTPUT((ompi_coll_base_framework.framework_output, "%s:%4d\tError occurred %d, rank %2d",
__FILE__, line, err, rank));
(void)line; // silence compiler warning
return err;
}
/*
* ompi_coll_base_allgather_intra_ring
*
* Function: allgather using O(N) steps.
* Accepts: Same arguments as MPI_Allgather
* Returns: MPI_SUCCESS or error code
*
* Description: Ring algorithm for all gather.
* At every step i, rank r receives message from rank (r - 1)
* containing data from rank (r - i - 1) and sends message to rank
* (r + 1) containing data from rank (r - i), with wrap arounds.
* Memory requirements:
* No additional memory requirements.
*
*/
int ompi_coll_base_allgather_intra_ring(const void *sbuf, int scount,
struct ompi_datatype_t *sdtype,
void* rbuf, int rcount,
struct ompi_datatype_t *rdtype,
struct ompi_communicator_t *comm,
mca_coll_base_module_t *module)
{
int line = -1, rank, size, err, sendto, recvfrom, i, recvdatafrom, senddatafrom;
ptrdiff_t rlb, rext;
char *tmpsend = NULL, *tmprecv = NULL;
size = ompi_comm_size(comm);
rank = ompi_comm_rank(comm);
OPAL_OUTPUT((ompi_coll_base_framework.framework_output,
"coll:base:allgather_intra_ring rank %d", rank));
err = ompi_datatype_get_extent (rdtype, &rlb, &rext);
if (MPI_SUCCESS != err) { line = __LINE__; goto err_hndl; }
/* Initialization step:
- if send buffer is not MPI_IN_PLACE, copy send buffer to appropriate block
of receive buffer
*/
tmprecv = (char*) rbuf + (ptrdiff_t)rank * (ptrdiff_t)rcount * rext;
if (MPI_IN_PLACE != sbuf) {
tmpsend = (char*) sbuf;
err = ompi_datatype_sndrcv(tmpsend, scount, sdtype, tmprecv, rcount, rdtype);
if (MPI_SUCCESS != err) { line = __LINE__; goto err_hndl; }
}
/* Communication step:
At every step i: 0 .. (P-1), rank r:
- receives message from [(r - 1 + size) % size] containing data from rank
[(r - i - 1 + size) % size]
- sends message to rank [(r + 1) % size] containing data from rank
[(r - i + size) % size]
- sends message which starts at begining of rbuf and has size
*/
sendto = (rank + 1) % size;
recvfrom = (rank - 1 + size) % size;
for (i = 0; i < size - 1; i++) {
recvdatafrom = (rank - i - 1 + size) % size;
senddatafrom = (rank - i + size) % size;
tmprecv = (char*)rbuf + (ptrdiff_t)recvdatafrom * (ptrdiff_t)rcount * rext;
tmpsend = (char*)rbuf + (ptrdiff_t)senddatafrom * (ptrdiff_t)rcount * rext;
/* Sendreceive */
err = ompi_coll_base_sendrecv(tmpsend, rcount, rdtype, sendto,
MCA_COLL_BASE_TAG_ALLGATHER,
tmprecv, rcount, rdtype, recvfrom,
MCA_COLL_BASE_TAG_ALLGATHER,
comm, MPI_STATUS_IGNORE, rank);
if (MPI_SUCCESS != err) { line = __LINE__; goto err_hndl; }
}
return OMPI_SUCCESS;
err_hndl:
OPAL_OUTPUT((ompi_coll_base_framework.framework_output, "%s:%4d\tError occurred %d, rank %2d",
__FILE__, line, err, rank));
(void)line; // silence compiler warning
return err;
}
/*
* ompi_coll_base_allgather_intra_neighborexchange
*
* Function: allgather using N/2 steps (O(N))
* Accepts: Same arguments as MPI_Allgather
* Returns: MPI_SUCCESS or error code
*
* Description: Neighbor Exchange algorithm for allgather.
* Described by Chen et.al. in
* "Performance Evaluation of Allgather Algorithms on
* Terascale Linux Cluster with Fast Ethernet",
* Proceedings of the Eighth International Conference on
* High-Performance Computing inn Asia-Pacific Region
* (HPCASIA'05), 2005
*
* Rank r exchanges message with one of its neighbors and
* forwards the data further in the next step.
*
* No additional memory requirements.
*
* Limitations: Algorithm works only on even number of processes.
* For odd number of processes we switch to ring algorithm.
*
* Example on 6 nodes:
* Initial state
* # 0 1 2 3 4 5
* [0] [ ] [ ] [ ] [ ] [ ]
* [ ] [1] [ ] [ ] [ ] [ ]
* [ ] [ ] [2] [ ] [ ] [ ]
* [ ] [ ] [ ] [3] [ ] [ ]
* [ ] [ ] [ ] [ ] [4] [ ]
* [ ] [ ] [ ] [ ] [ ] [5]
* Step 0:
* # 0 1 2 3 4 5
* [0] [0] [ ] [ ] [ ] [ ]
* [1] [1] [ ] [ ] [ ] [ ]
* [ ] [ ] [2] [2] [ ] [ ]
* [ ] [ ] [3] [3] [ ] [ ]
* [ ] [ ] [ ] [ ] [4] [4]
* [ ] [ ] [ ] [ ] [5] [5]
* Step 1:
* # 0 1 2 3 4 5
* [0] [0] [0] [ ] [ ] [0]
* [1] [1] [1] [ ] [ ] [1]
* [ ] [2] [2] [2] [2] [ ]
* [ ] [3] [3] [3] [3] [ ]
* [4] [ ] [ ] [4] [4] [4]
* [5] [ ] [ ] [5] [5] [5]
* Step 2:
* # 0 1 2 3 4 5
* [0] [0] [0] [0] [0] [0]
* [1] [1] [1] [1] [1] [1]
* [2] [2] [2] [2] [2] [2]
* [3] [3] [3] [3] [3] [3]
* [4] [4] [4] [4] [4] [4]
* [5] [5] [5] [5] [5] [5]
*/
int
ompi_coll_base_allgather_intra_neighborexchange(const void *sbuf, int scount,
struct ompi_datatype_t *sdtype,
void* rbuf, int rcount,
struct ompi_datatype_t *rdtype,
struct ompi_communicator_t *comm,
mca_coll_base_module_t *module)
{
int line = -1, rank, size, i, even_rank, err;
int neighbor[2], offset_at_step[2], recv_data_from[2], send_data_from;
ptrdiff_t rlb, rext;
char *tmpsend = NULL, *tmprecv = NULL;
size = ompi_comm_size(comm);
rank = ompi_comm_rank(comm);
if (size % 2) {
OPAL_OUTPUT((ompi_coll_base_framework.framework_output,
"coll:base:allgather_intra_neighborexchange WARNING: odd size %d, switching to ring algorithm",
size));
return ompi_coll_base_allgather_intra_ring(sbuf, scount, sdtype,
rbuf, rcount, rdtype,
comm, module);
}
OPAL_OUTPUT((ompi_coll_base_framework.framework_output,
"coll:base:allgather_intra_neighborexchange rank %d", rank));
err = ompi_datatype_get_extent (rdtype, &rlb, &rext);
if (MPI_SUCCESS != err) { line = __LINE__; goto err_hndl; }
/* Initialization step:
- if send buffer is not MPI_IN_PLACE, copy send buffer to appropriate block
of receive buffer
*/
tmprecv = (char*) rbuf + (ptrdiff_t)rank *(ptrdiff_t) rcount * rext;
if (MPI_IN_PLACE != sbuf) {
tmpsend = (char*) sbuf;
err = ompi_datatype_sndrcv(tmpsend, scount, sdtype, tmprecv, rcount, rdtype);
if (MPI_SUCCESS != err) { line = __LINE__; goto err_hndl; }
}
/* Determine neighbors, order in which blocks will arrive, etc. */
even_rank = !(rank % 2);
if (even_rank) {
neighbor[0] = (rank + 1) % size;
neighbor[1] = (rank - 1 + size) % size;
recv_data_from[0] = rank;
recv_data_from[1] = rank;
offset_at_step[0] = (+2);
offset_at_step[1] = (-2);
} else {
neighbor[0] = (rank - 1 + size) % size;
neighbor[1] = (rank + 1) % size;
recv_data_from[0] = neighbor[0];
recv_data_from[1] = neighbor[0];
offset_at_step[0] = (-2);
offset_at_step[1] = (+2);
}
/* Communication loop:
- First step is special: exchange a single block with neighbor[0].
- Rest of the steps:
update recv_data_from according to offset, and
exchange two blocks with appropriate neighbor.
the send location becomes previous receve location.
*/
tmprecv = (char*)rbuf + (ptrdiff_t)neighbor[0] * (ptrdiff_t)rcount * rext;
tmpsend = (char*)rbuf + (ptrdiff_t)rank * (ptrdiff_t)rcount * rext;
/* Sendreceive */
err = ompi_coll_base_sendrecv(tmpsend, rcount, rdtype, neighbor[0],
MCA_COLL_BASE_TAG_ALLGATHER,
tmprecv, rcount, rdtype, neighbor[0],
MCA_COLL_BASE_TAG_ALLGATHER,
comm, MPI_STATUS_IGNORE, rank);
if (MPI_SUCCESS != err) { line = __LINE__; goto err_hndl; }
/* Determine initial sending location */
if (even_rank) {
send_data_from = rank;
} else {
send_data_from = recv_data_from[0];
}
for (i = 1; i < (size / 2); i++) {
const int i_parity = i % 2;
recv_data_from[i_parity] =
(recv_data_from[i_parity] + offset_at_step[i_parity] + size) % size;
tmprecv = (char*)rbuf + (ptrdiff_t)recv_data_from[i_parity] * (ptrdiff_t)rcount * rext;
tmpsend = (char*)rbuf + (ptrdiff_t)send_data_from * rcount * rext;
/* Sendreceive */
err = ompi_coll_base_sendrecv(tmpsend, (ptrdiff_t)2 * (ptrdiff_t)rcount, rdtype,
neighbor[i_parity],
MCA_COLL_BASE_TAG_ALLGATHER,
tmprecv, (ptrdiff_t)2 * (ptrdiff_t)rcount, rdtype,
neighbor[i_parity],
MCA_COLL_BASE_TAG_ALLGATHER,
comm, MPI_STATUS_IGNORE, rank);
if (MPI_SUCCESS != err) { line = __LINE__; goto err_hndl; }
send_data_from = recv_data_from[i_parity];
}
return OMPI_SUCCESS;
err_hndl:
OPAL_OUTPUT((ompi_coll_base_framework.framework_output, "%s:%4d\tError occurred %d, rank %2d",
__FILE__, line, err, rank));
(void)line; // silence compiler warning
return err;
}
int ompi_coll_base_allgather_intra_two_procs(const void *sbuf, int scount,
struct ompi_datatype_t *sdtype,
void* rbuf, int rcount,
struct ompi_datatype_t *rdtype,
struct ompi_communicator_t *comm,
mca_coll_base_module_t *module)
{
int line = -1, err, rank, remote;
char *tmpsend = NULL, *tmprecv = NULL;
ptrdiff_t rext, lb;
rank = ompi_comm_rank(comm);
OPAL_OUTPUT((ompi_coll_base_framework.framework_output,
"ompi_coll_base_allgather_intra_two_procs rank %d", rank));
if (2 != ompi_comm_size(comm)) {
return MPI_ERR_UNSUPPORTED_OPERATION;
}
err = ompi_datatype_get_extent (rdtype, &lb, &rext);
if (MPI_SUCCESS != err) { line = __LINE__; goto err_hndl; }
/* Exchange data:
- compute source and destinations
- send receive data
*/
remote = rank ^ 0x1;
tmpsend = (char*)sbuf;
if (MPI_IN_PLACE == sbuf) {
tmpsend = (char*)rbuf + (ptrdiff_t)rank * (ptrdiff_t)rcount * rext;
scount = rcount;
sdtype = rdtype;
}
tmprecv = (char*)rbuf + (ptrdiff_t)remote * (ptrdiff_t)rcount * rext;
err = ompi_coll_base_sendrecv(tmpsend, scount, sdtype, remote,
MCA_COLL_BASE_TAG_ALLGATHER,
tmprecv, rcount, rdtype, remote,
MCA_COLL_BASE_TAG_ALLGATHER,
comm, MPI_STATUS_IGNORE, rank);
if (MPI_SUCCESS != err) { line = __LINE__; goto err_hndl; }
/* Place your data in correct location if necessary */
if (MPI_IN_PLACE != sbuf) {
err = ompi_datatype_sndrcv((char*)sbuf, scount, sdtype,
(char*)rbuf + (ptrdiff_t)rank * (ptrdiff_t)rcount * rext, rcount, rdtype);
if (MPI_SUCCESS != err) { line = __LINE__; goto err_hndl; }
}
return MPI_SUCCESS;
err_hndl:
OPAL_OUTPUT((ompi_coll_base_framework.framework_output, "%s:%4d\tError occurred %d, rank %2d",
__FILE__, line, err, rank));
(void)line; // silence compiler warning
return err;
}
/*
* Linear functions are copied from the BASIC coll module
* they do not segment the message and are simple implementations
* but for some small number of nodes and/or small data sizes they
* are just as fast as base/tree based segmenting operations
* and as such may be selected by the decision functions
* These are copied into this module due to the way we select modules
* in V1. i.e. in V2 we will handle this differently and so will not
* have to duplicate code.
* JPG following the examples from other coll_base implementations. Dec06.
*/
/* copied function (with appropriate renaming) starts here */
/*
* allgather_intra_basic_linear
*
* Function: - allgather using other MPI collections
* Accepts: - same as MPI_Allgather()
* Returns: - MPI_SUCCESS or error code
*/
int
ompi_coll_base_allgather_intra_basic_linear(const void *sbuf, int scount,
struct ompi_datatype_t *sdtype,
void *rbuf,
int rcount,
struct ompi_datatype_t *rdtype,
struct ompi_communicator_t *comm,
mca_coll_base_module_t *module)
{
int err;
ptrdiff_t lb, extent;
/* Handle MPI_IN_PLACE (see explanantion in reduce.c for how to
allocate temp buffer) -- note that rank 0 can use IN_PLACE
natively, and we can just alias the right position in rbuf
as sbuf and avoid using a temporary buffer if gather is
implemented correctly */
if (MPI_IN_PLACE == sbuf && 0 != ompi_comm_rank(comm)) {
ompi_datatype_get_extent(rdtype, &lb, &extent);
sbuf = ((char*) rbuf) + (ompi_comm_rank(comm) * extent * rcount);
sdtype = rdtype;
scount = rcount;
}
/* Gather and broadcast. */
err = comm->c_coll->coll_gather(sbuf, scount, sdtype,
rbuf, rcount, rdtype,
0, comm, comm->c_coll->coll_gather_module);
if (MPI_SUCCESS == err) {
size_t length = (ptrdiff_t)rcount * ompi_comm_size(comm);
if( length < (size_t)INT_MAX ) {
err = comm->c_coll->coll_bcast(rbuf, (ptrdiff_t)rcount * ompi_comm_size(comm), rdtype,
0, comm, comm->c_coll->coll_bcast_module);
} else {
ompi_datatype_t* temptype;
ompi_datatype_create_contiguous(ompi_comm_size(comm), rdtype, &temptype);
ompi_datatype_commit(&temptype);
err = comm->c_coll->coll_bcast(rbuf, rcount, temptype,
0, comm, comm->c_coll->coll_bcast_module);
ompi_datatype_destroy(&temptype);
}
}
/* All done */
return err;
}
/* copied function (with appropriate renaming) ends here */