* Accepts: Same arguments as MPI_Allgatherv
* Returns: MPI_SUCCESS or error code
*
- * Description: Neighbor Exchange algorithm for allgather adapted for
+ * Description: Neighbor Exchange algorithm for allgather adapted for
* allgatherv.
- * Described by Chen et.al. in
- * "Performance Evaluation of Allgather Algorithms on
+ * 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
+ * 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
* [4] [4] [4] [4] [4] [4]
* [5] [5] [5] [5] [5] [5]
*/
-
+
#include "../colls_private.h"
-
+
namespace simgrid{
namespace smpi{
-int
+int
Coll_allgatherv_ompi_neighborexchange::allgatherv(void *sbuf, int scount,
MPI_Datatype sdtype,
void* rbuf, int *rcounts, int *rdispls,
int line = -1;
int rank, size;
int neighbor[2], offset_at_step[2], recv_data_from[2], send_data_from;
-
+
int i, even_rank;
int err = 0;
ptrdiff_t slb, rlb, sext, rext;
if (size % 2) {
XBT_DEBUG(
- "coll:tuned:allgatherv_ompi_neighborexchange WARNING: odd size %d, switching to ring algorithm",
+ "coll:tuned:allgatherv_ompi_neighborexchange WARNING: odd size %d, switching to ring algorithm",
size);
return Coll_allgatherv_ring::allgatherv(sbuf, scount, sdtype,
- rbuf, rcounts,
+ rbuf, rcounts,
rdispls, rdtype,
comm);
}
if (MPI_SUCCESS != err) { line = __LINE__; goto err_hndl; }
/* Initialization step:
- - if send buffer is not MPI_IN_PLACE, copy send buffer to
+ - if send buffer is not MPI_IN_PLACE, copy send buffer to
the appropriate block of receive buffer
*/
tmprecv = (char*) rbuf + rdispls[rank] * rext;
if (MPI_IN_PLACE != sbuf) {
tmpsend = (char*) sbuf;
- err = Datatype::copy(tmpsend, scount, sdtype,
+ err = Datatype::copy(tmpsend, scount, sdtype,
tmprecv, rcounts[rank], rdtype);
if (MPI_SUCCESS != err) { line = __LINE__; goto err_hndl; }
- }
+ }
/* Determine neighbors, order in which blocks will arrive, etc. */
even_rank = !(rank % 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
+ - 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.
Note, we need to create indexed datatype to send and receive these
*/
tmprecv = (char*)rbuf + rdispls[neighbor[0]] * rext;
tmpsend = (char*)rbuf + rdispls[rank] * rext;
- Request::sendrecv(tmpsend, rcounts[rank], rdtype,
+ Request::sendrecv(tmpsend, rcounts[rank], rdtype,
neighbor[0], COLL_TAG_ALLGATHERV,
- tmprecv, rcounts[neighbor[0]], rdtype,
+ tmprecv, rcounts[neighbor[0]], rdtype,
neighbor[0], COLL_TAG_ALLGATHERV,
comm, MPI_STATUS_IGNORE);
-
-
+
+
/* Determine initial sending counts and displacements*/
if (even_rank) {
send_data_from = rank;
MPI_Datatype new_rdtype, new_sdtype;
int new_scounts[2], new_sdispls[2], new_rcounts[2], new_rdispls[2];
const int i_parity = i % 2;
- recv_data_from[i_parity] =
+ recv_data_from[i_parity] =
(recv_data_from[i_parity] + offset_at_step[i_parity] + size) % size;
/* Create new indexed types for sending and receiving.
We are receiving data from ranks (recv_data_from[i_parity]) and
(recv_data_from[i_parity]+1).
*/
-
+
new_scounts[0] = rcounts[send_data_from];
new_scounts[1] = rcounts[(send_data_from + 1)];
new_sdispls[0] = rdispls[send_data_from];
new_sdispls[1] = rdispls[(send_data_from + 1)];
- err = Datatype::create_indexed(2, new_scounts, new_sdispls, rdtype,
+ err = Datatype::create_indexed(2, new_scounts, new_sdispls, rdtype,
&new_sdtype);
if (MPI_SUCCESS != err) { line = __LINE__; goto err_hndl; }
new_sdtype->commit();
new_rcounts[1] = rcounts[(recv_data_from[i_parity] + 1)];
new_rdispls[0] = rdispls[recv_data_from[i_parity]];
new_rdispls[1] = rdispls[(recv_data_from[i_parity] + 1)];
- err = Datatype::create_indexed(2, new_rcounts, new_rdispls, rdtype,
+ err = Datatype::create_indexed(2, new_rcounts, new_rdispls, rdtype,
&new_rdtype);
if (MPI_SUCCESS != err) { line = __LINE__; goto err_hndl; }
new_rdtype->commit();
-
+
tmprecv = (char*)rbuf;
tmpsend = (char*)rbuf;
-
+
/* Sendreceive */
Request::sendrecv(tmpsend, 1, new_sdtype, neighbor[i_parity],
COLL_TAG_ALLGATHERV,
comm, MPI_STATUS_IGNORE);
send_data_from = recv_data_from[i_parity];
-
+
Datatype::unref(new_sdtype);
Datatype::unref(new_rdtype);
}
