1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
|
/* -*- Mode: C; c-basic-offset:4 ; indent-tabs-mode:nil -*- */
/*
* Copyright (c) 2018 Siberian State University of Telecommunications
* and Information Science. All rights reserved.
* Copyright (c) 2018 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 "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_base_functions.h"
#include "ompi/mca/coll/base/coll_tags.h"
#include "ompi/mca/coll/base/coll_base_util.h"
#include "ompi/mca/pml/pml.h"
#include "ompi/op/op.h"
/*
* ompi_coll_base_scan_intra_linear
*
* Function: Linear algorithm for inclusive scan.
* Accepts: Same as MPI_Scan
* Returns: MPI_SUCCESS or error code
*/
int
ompi_coll_base_scan_intra_linear(const void *sbuf, void *rbuf, int count,
struct ompi_datatype_t *dtype,
struct ompi_op_t *op,
struct ompi_communicator_t *comm,
mca_coll_base_module_t *module)
{
int size, rank, err;
ptrdiff_t dsize, gap;
char *free_buffer = NULL;
char *pml_buffer = NULL;
/* Initialize */
rank = ompi_comm_rank(comm);
size = ompi_comm_size(comm);
/* If I'm rank 0, just copy into the receive buffer */
if (0 == rank) {
if (MPI_IN_PLACE != sbuf) {
err = ompi_datatype_copy_content_same_ddt(dtype, count, (char*)rbuf, (char*)sbuf);
if (MPI_SUCCESS != err) {
return err;
}
}
}
/* Otherwise receive previous buffer and reduce. */
else {
/* Allocate a temporary buffer. Rationale for this size is
* listed in coll_basic_reduce.c. Use this temporary buffer to
* receive into, later. */
dsize = opal_datatype_span(&dtype->super, count, &gap);
free_buffer = malloc(dsize);
if (NULL == free_buffer) {
return OMPI_ERR_OUT_OF_RESOURCE;
}
pml_buffer = free_buffer - gap;
/* Copy the send buffer into the receive buffer. */
if (MPI_IN_PLACE != sbuf) {
err = ompi_datatype_copy_content_same_ddt(dtype, count, (char*)rbuf, (char*)sbuf);
if (MPI_SUCCESS != err) {
if (NULL != free_buffer) {
free(free_buffer);
}
return err;
}
}
/* Receive the prior answer */
err = MCA_PML_CALL(recv(pml_buffer, count, dtype,
rank - 1, MCA_COLL_BASE_TAG_SCAN, comm,
MPI_STATUS_IGNORE));
if (MPI_SUCCESS != err) {
if (NULL != free_buffer) {
free(free_buffer);
}
return err;
}
/* Perform the operation */
ompi_op_reduce(op, pml_buffer, rbuf, count, dtype);
/* All done */
if (NULL != free_buffer) {
free(free_buffer);
}
}
/* Send result to next process. */
if (rank < (size - 1)) {
return MCA_PML_CALL(send(rbuf, count, dtype, rank + 1,
MCA_COLL_BASE_TAG_SCAN,
MCA_PML_BASE_SEND_STANDARD, comm));
}
/* All done */
return MPI_SUCCESS;
}
/*
* ompi_coll_base_scan_intra_recursivedoubling
*
* Function: Recursive doubling algorithm for inclusive scan.
* Accepts: Same as MPI_Scan
* Returns: MPI_SUCCESS or error code
*
* Description: Implements recursive doubling algorithm for MPI_Scan.
* The algorithm preserves order of operations so it can
* be used both by commutative and non-commutative operations.
*
* Example for 5 processes and commutative operation MPI_SUM:
* Process: 0 1 2 3 4
* recvbuf: [0] [1] [2] [3] [4]
* psend: [0] [1] [2] [3] [4]
*
* Step 1:
* recvbuf: [0] [0+1] [2] [2+3] [4]
* psend: [1+0] [0+1] [3+2] [2+3] [4]
*
* Step 2:
* recvbuf: [0] [0+1] [(1+0)+2] [(1+0)+(2+3)] [4]
* psend: [(3+2)+(1+0)] [(2+3)+(0+1)] [(1+0)+(3+2)] [(1+0)+(2+3)] [4]
*
* Step 3:
* recvbuf: [0] [0+1] [(1+0)+2] [(1+0)+(2+3)] [((3+2)+(1+0))+4]
* psend: [4+((3+2)+(1+0))] [((3+2)+(1+0))+4]
*
* Time complexity (worst case): \ceil(\log_2(p))(2\alpha + 2m\beta + 2m\gamma)
* Memory requirements (per process): 2 * count * typesize = O(count)
* Limitations: intra-communicators only
*/
int ompi_coll_base_scan_intra_recursivedoubling(
const void *sendbuf, void *recvbuf, int count, struct ompi_datatype_t *datatype,
struct ompi_op_t *op, struct ompi_communicator_t *comm,
mca_coll_base_module_t *module)
{
int err = MPI_SUCCESS;
char *tmpsend_raw = NULL, *tmprecv_raw = NULL;
int comm_size = ompi_comm_size(comm);
int rank = ompi_comm_rank(comm);
OPAL_OUTPUT((ompi_coll_base_framework.framework_output,
"coll:base:scan_intra_recursivedoubling: rank %d/%d",
rank, comm_size));
if (count == 0)
return MPI_SUCCESS;
if (sendbuf != MPI_IN_PLACE) {
err = ompi_datatype_copy_content_same_ddt(datatype, count, recvbuf, (char *)sendbuf);
if (MPI_SUCCESS != err) { goto cleanup_and_return; }
}
if (comm_size < 2)
return MPI_SUCCESS;
ptrdiff_t dsize, gap;
dsize = opal_datatype_span(&datatype->super, count, &gap);
tmpsend_raw = malloc(dsize);
tmprecv_raw = malloc(dsize);
if (NULL == tmpsend_raw || NULL == tmprecv_raw) {
err = OMPI_ERR_OUT_OF_RESOURCE;
goto cleanup_and_return;
}
char *psend = tmpsend_raw - gap;
char *precv = tmprecv_raw - gap;
err = ompi_datatype_copy_content_same_ddt(datatype, count, psend, recvbuf);
if (MPI_SUCCESS != err) { goto cleanup_and_return; }
int is_commute = ompi_op_is_commute(op);
for (int mask = 1; mask < comm_size; mask <<= 1) {
int remote = rank ^ mask;
if (remote < comm_size) {
err = ompi_coll_base_sendrecv(psend, count, datatype, remote,
MCA_COLL_BASE_TAG_SCAN,
precv, count, datatype, remote,
MCA_COLL_BASE_TAG_SCAN, comm,
MPI_STATUS_IGNORE, rank);
if (MPI_SUCCESS != err) { goto cleanup_and_return; }
if (rank > remote) {
/* Accumulate prefix reduction: recvbuf = precv <op> recvbuf */
ompi_op_reduce(op, precv, recvbuf, count, datatype);
/* Partial result: psend = precv <op> psend */
ompi_op_reduce(op, precv, psend, count, datatype);
} else {
if (is_commute) {
/* psend = precv <op> psend */
ompi_op_reduce(op, precv, psend, count, datatype);
} else {
/* precv = psend <op> precv */
ompi_op_reduce(op, psend, precv, count, datatype);
char *tmp = psend;
psend = precv;
precv = tmp;
}
}
}
}
cleanup_and_return:
if (NULL != tmpsend_raw)
free(tmpsend_raw);
if (NULL != tmprecv_raw)
free(tmprecv_raw);
return err;
}
|
