Actual source code: mpits.c
1: #include <petscsys.h>
2: #include <petsc/private/petscimpl.h>
4: PetscLogEvent PETSC_BuildTwoSided;
5: PetscLogEvent PETSC_BuildTwoSidedF;
7: const char *const PetscBuildTwoSidedTypes[] = {"ALLREDUCE", "IBARRIER", "REDSCATTER", "PetscBuildTwoSidedType", "PETSC_BUILDTWOSIDED_", NULL};
9: static PetscBuildTwoSidedType _twosided_type = PETSC_BUILDTWOSIDED_NOTSET;
11: /*@
12: PetscCommBuildTwoSidedSetType - set algorithm to use when building two-sided communication
14: Logically Collective
16: Input Parameters:
17: + comm - `PETSC_COMM_WORLD`
18: - twosided - algorithm to use in subsequent calls to `PetscCommBuildTwoSided()`
20: Level: developer
22: Note:
23: This option is currently global, but could be made per-communicator.
25: .seealso: `PetscCommBuildTwoSided()`, `PetscCommBuildTwoSidedGetType()`, `PetscBuildTwoSidedType`
26: @*/
27: PetscErrorCode PetscCommBuildTwoSidedSetType(MPI_Comm comm, PetscBuildTwoSidedType twosided)
28: {
29: PetscFunctionBegin;
31: PetscMPIInt b1[2], b2[2];
32: b1[0] = -(PetscMPIInt)twosided;
33: b1[1] = (PetscMPIInt)twosided;
34: PetscCall(MPIU_Allreduce(b1, b2, 2, MPI_INT, MPI_MAX, comm));
35: PetscCheck(-b2[0] == b2[1], comm, PETSC_ERR_ARG_WRONG, "Enum value must be same on all processes");
36: }
37: _twosided_type = twosided;
38: PetscFunctionReturn(PETSC_SUCCESS);
39: }
41: /*@
42: PetscCommBuildTwoSidedGetType - get algorithm used when building two-sided communication
44: Logically Collective
46: Output Parameters:
47: + comm - communicator on which to query algorithm
48: - twosided - algorithm to use for `PetscCommBuildTwoSided()`
50: Level: developer
52: .seealso: `PetscCommBuildTwoSided()`, `PetscCommBuildTwoSidedSetType()`, `PetscBuildTwoSidedType`
53: @*/
54: PetscErrorCode PetscCommBuildTwoSidedGetType(MPI_Comm comm, PetscBuildTwoSidedType *twosided)
55: {
56: PetscMPIInt size;
58: PetscFunctionBegin;
59: *twosided = PETSC_BUILDTWOSIDED_NOTSET;
60: if (_twosided_type == PETSC_BUILDTWOSIDED_NOTSET) {
61: PetscCallMPI(MPI_Comm_size(comm, &size));
62: _twosided_type = PETSC_BUILDTWOSIDED_ALLREDUCE; /* default for small comms, see https://gitlab.com/petsc/petsc/-/merge_requests/2611 */
63: #if defined(PETSC_HAVE_MPI_NONBLOCKING_COLLECTIVES)
64: if (size > 1024) _twosided_type = PETSC_BUILDTWOSIDED_IBARRIER;
65: #endif
66: PetscCall(PetscOptionsGetEnum(NULL, NULL, "-build_twosided", PetscBuildTwoSidedTypes, (PetscEnum *)&_twosided_type, NULL));
67: }
68: *twosided = _twosided_type;
69: PetscFunctionReturn(PETSC_SUCCESS);
70: }
72: #if defined(PETSC_HAVE_MPI_NONBLOCKING_COLLECTIVES)
73: static PetscErrorCode PetscCommBuildTwoSided_Ibarrier(MPI_Comm comm, PetscMPIInt count, MPI_Datatype dtype, PetscMPIInt nto, const PetscMPIInt *toranks, const void *todata, PetscMPIInt *nfrom, PetscMPIInt **fromranks, void *fromdata)
74: {
75: PetscMPIInt nrecvs, tag, done, i;
76: MPI_Aint lb, unitbytes;
77: char *tdata;
78: MPI_Request *sendreqs, barrier;
79: PetscSegBuffer segrank, segdata;
80: PetscBool barrier_started;
82: PetscFunctionBegin;
83: PetscCall(PetscCommDuplicate(comm, &comm, &tag));
84: PetscCallMPI(MPI_Type_get_extent(dtype, &lb, &unitbytes));
85: PetscCheck(lb == 0, comm, PETSC_ERR_SUP, "Datatype with nonzero lower bound %ld", (long)lb);
86: tdata = (char *)todata;
87: PetscCall(PetscMalloc1(nto, &sendreqs));
88: for (i = 0; i < nto; i++) PetscCallMPI(MPI_Issend((void *)(tdata + count * unitbytes * i), count, dtype, toranks[i], tag, comm, sendreqs + i));
89: PetscCall(PetscSegBufferCreate(sizeof(PetscMPIInt), 4, &segrank));
90: PetscCall(PetscSegBufferCreate(unitbytes, 4 * count, &segdata));
92: nrecvs = 0;
93: barrier = MPI_REQUEST_NULL;
94: /* MPICH-3.2 sometimes does not create a request in some "optimized" cases. This is arguably a standard violation,
95: * but we need to work around it. */
96: barrier_started = PETSC_FALSE;
97: for (done = 0; !done;) {
98: PetscMPIInt flag;
99: MPI_Status status;
100: PetscCallMPI(MPI_Iprobe(MPI_ANY_SOURCE, tag, comm, &flag, &status));
101: if (flag) { /* incoming message */
102: PetscMPIInt *recvrank;
103: void *buf;
104: PetscCall(PetscSegBufferGet(segrank, 1, &recvrank));
105: PetscCall(PetscSegBufferGet(segdata, count, &buf));
106: *recvrank = status.MPI_SOURCE;
107: PetscCallMPI(MPI_Recv(buf, count, dtype, status.MPI_SOURCE, tag, comm, MPI_STATUS_IGNORE));
108: nrecvs++;
109: }
110: if (!barrier_started) {
111: PetscMPIInt sent, nsends;
112: PetscCall(PetscMPIIntCast(nto, &nsends));
113: PetscCallMPI(MPI_Testall(nsends, sendreqs, &sent, MPI_STATUSES_IGNORE));
114: if (sent) {
115: PetscCallMPI(MPI_Ibarrier(comm, &barrier));
116: barrier_started = PETSC_TRUE;
117: PetscCall(PetscFree(sendreqs));
118: }
119: } else {
120: PetscCallMPI(MPI_Test(&barrier, &done, MPI_STATUS_IGNORE));
121: }
122: }
123: *nfrom = nrecvs;
124: PetscCall(PetscSegBufferExtractAlloc(segrank, fromranks));
125: PetscCall(PetscSegBufferDestroy(&segrank));
126: PetscCall(PetscSegBufferExtractAlloc(segdata, fromdata));
127: PetscCall(PetscSegBufferDestroy(&segdata));
128: PetscCall(PetscCommDestroy(&comm));
129: PetscFunctionReturn(PETSC_SUCCESS);
130: }
131: #endif
133: static PetscErrorCode PetscCommBuildTwoSided_Allreduce(MPI_Comm comm, PetscMPIInt count, MPI_Datatype dtype, PetscMPIInt nto, const PetscMPIInt *toranks, const void *todata, PetscMPIInt *nfrom, PetscMPIInt **fromranks, void *fromdata)
134: {
135: PetscMPIInt size, rank, *iflags, nrecvs, tag, *franks, i, flg;
136: MPI_Aint lb, unitbytes;
137: char *tdata, *fdata;
138: MPI_Request *reqs, *sendreqs;
139: MPI_Status *statuses;
140: PetscCommCounter *counter;
142: PetscFunctionBegin;
143: PetscCallMPI(MPI_Comm_size(comm, &size));
144: PetscCallMPI(MPI_Comm_rank(comm, &rank));
145: PetscCall(PetscCommDuplicate(comm, &comm, &tag));
146: PetscCallMPI(MPI_Comm_get_attr(comm, Petsc_Counter_keyval, &counter, &flg));
147: PetscCheck(flg, PETSC_COMM_SELF, PETSC_ERR_PLIB, "Inner PETSc communicator does not have its tag/name counter attribute set");
148: if (!counter->iflags) {
149: PetscCall(PetscCalloc1(size, &counter->iflags));
150: iflags = counter->iflags;
151: } else {
152: iflags = counter->iflags;
153: PetscCall(PetscArrayzero(iflags, size));
154: }
155: for (i = 0; i < nto; i++) iflags[toranks[i]] = 1;
156: PetscCall(MPIU_Allreduce(MPI_IN_PLACE, iflags, size, MPI_INT, MPI_SUM, comm));
157: nrecvs = iflags[rank];
158: PetscCallMPI(MPI_Type_get_extent(dtype, &lb, &unitbytes));
159: PetscCheck(lb == 0, comm, PETSC_ERR_SUP, "Datatype with nonzero lower bound %ld", (long)lb);
160: PetscCall(PetscMalloc(nrecvs * count * unitbytes, &fdata));
161: tdata = (char *)todata;
162: PetscCall(PetscMalloc2(nto + nrecvs, &reqs, nto + nrecvs, &statuses));
163: sendreqs = PetscSafePointerPlusOffset(reqs, nrecvs);
164: for (i = 0; i < nrecvs; i++) PetscCallMPI(MPI_Irecv((void *)(fdata + count * unitbytes * i), count, dtype, MPI_ANY_SOURCE, tag, comm, reqs + i));
165: for (i = 0; i < nto; i++) PetscCallMPI(MPI_Isend((void *)(tdata + count * unitbytes * i), count, dtype, toranks[i], tag, comm, sendreqs + i));
166: PetscCallMPI(MPI_Waitall(nto + nrecvs, reqs, statuses));
167: PetscCall(PetscMalloc1(nrecvs, &franks));
168: for (i = 0; i < nrecvs; i++) franks[i] = statuses[i].MPI_SOURCE;
169: PetscCall(PetscFree2(reqs, statuses));
170: PetscCall(PetscCommDestroy(&comm));
172: *nfrom = nrecvs;
173: *fromranks = franks;
174: *(void **)fromdata = fdata;
175: PetscFunctionReturn(PETSC_SUCCESS);
176: }
178: #if defined(PETSC_HAVE_MPI_REDUCE_SCATTER_BLOCK)
179: static PetscErrorCode PetscCommBuildTwoSided_RedScatter(MPI_Comm comm, PetscMPIInt count, MPI_Datatype dtype, PetscMPIInt nto, const PetscMPIInt *toranks, const void *todata, PetscMPIInt *nfrom, PetscMPIInt **fromranks, void *fromdata)
180: {
181: PetscMPIInt size, *iflags, nrecvs, tag, *franks, i, flg;
182: MPI_Aint lb, unitbytes;
183: char *tdata, *fdata;
184: MPI_Request *reqs, *sendreqs;
185: MPI_Status *statuses;
186: PetscCommCounter *counter;
188: PetscFunctionBegin;
189: PetscCallMPI(MPI_Comm_size(comm, &size));
190: PetscCall(PetscCommDuplicate(comm, &comm, &tag));
191: PetscCallMPI(MPI_Comm_get_attr(comm, Petsc_Counter_keyval, &counter, &flg));
192: PetscCheck(flg, PETSC_COMM_SELF, PETSC_ERR_PLIB, "Inner PETSc communicator does not have its tag/name counter attribute set");
193: if (!counter->iflags) {
194: PetscCall(PetscCalloc1(size, &counter->iflags));
195: iflags = counter->iflags;
196: } else {
197: iflags = counter->iflags;
198: PetscCall(PetscArrayzero(iflags, size));
199: }
200: for (i = 0; i < nto; i++) iflags[toranks[i]] = 1;
201: PetscCallMPI(MPI_Reduce_scatter_block(iflags, &nrecvs, 1, MPI_INT, MPI_SUM, comm));
202: PetscCallMPI(MPI_Type_get_extent(dtype, &lb, &unitbytes));
203: PetscCheck(lb == 0, comm, PETSC_ERR_SUP, "Datatype with nonzero lower bound %ld", (long)lb);
204: PetscCall(PetscMalloc(nrecvs * count * unitbytes, &fdata));
205: tdata = (char *)todata;
206: PetscCall(PetscMalloc2(nto + nrecvs, &reqs, nto + nrecvs, &statuses));
207: sendreqs = reqs + nrecvs;
208: for (i = 0; i < nrecvs; i++) PetscCallMPI(MPI_Irecv((void *)(fdata + count * unitbytes * i), count, dtype, MPI_ANY_SOURCE, tag, comm, reqs + i));
209: for (i = 0; i < nto; i++) PetscCallMPI(MPI_Isend((void *)(tdata + count * unitbytes * i), count, dtype, toranks[i], tag, comm, sendreqs + i));
210: PetscCallMPI(MPI_Waitall(nto + nrecvs, reqs, statuses));
211: PetscCall(PetscMalloc1(nrecvs, &franks));
212: for (i = 0; i < nrecvs; i++) franks[i] = statuses[i].MPI_SOURCE;
213: PetscCall(PetscFree2(reqs, statuses));
214: PetscCall(PetscCommDestroy(&comm));
216: *nfrom = nrecvs;
217: *fromranks = franks;
218: *(void **)fromdata = fdata;
219: PetscFunctionReturn(PETSC_SUCCESS);
220: }
221: #endif
223: /*@C
224: PetscCommBuildTwoSided - discovers communicating ranks given one-sided information, moving constant-sized data in the process (often message lengths)
226: Collective
228: Input Parameters:
229: + comm - communicator
230: . count - number of entries to send/receive (must match on all ranks)
231: . dtype - datatype to send/receive from each rank (must match on all ranks)
232: . nto - number of ranks to send data to
233: . toranks - ranks to send to (array of length nto)
234: - todata - data to send to each rank (packed)
236: Output Parameters:
237: + nfrom - number of ranks receiving messages from
238: . fromranks - ranks receiving messages from (length `nfrom`, caller should `PetscFree()`)
239: - fromdata - packed data from each rank, each with count entries of type dtype (length nfrom, caller responsible for `PetscFree()`)
241: Options Database Key:
242: . -build_twosided <allreduce|ibarrier|redscatter> - algorithm to set up two-sided communication. Default is allreduce for communicators with <= 1024 ranks,
243: otherwise ibarrier.
245: Level: developer
247: Notes:
248: This memory-scalable interface is an alternative to calling `PetscGatherNumberOfMessages()` and
249: `PetscGatherMessageLengths()`, possibly with a subsequent round of communication to send other constant-size data, see {cite}`hoeflersiebretlumsdaine10`.
251: Basic data types as well as contiguous types are supported, but non-contiguous (e.g., strided) types are not.
253: .seealso: `PetscGatherNumberOfMessages()`, `PetscGatherMessageLengths()`, `PetscCommBuildTwoSidedSetType()`, `PetscCommBuildTwoSidedType`
254: @*/
255: PetscErrorCode PetscCommBuildTwoSided(MPI_Comm comm, PetscMPIInt count, MPI_Datatype dtype, PetscMPIInt nto, const PetscMPIInt *toranks, const void *todata, PetscMPIInt *nfrom, PetscMPIInt **fromranks, void *fromdata)
256: {
257: PetscBuildTwoSidedType buildtype = PETSC_BUILDTWOSIDED_NOTSET;
259: PetscFunctionBegin;
260: PetscCall(PetscSysInitializePackage());
261: PetscCall(PetscLogEventSync(PETSC_BuildTwoSided, comm));
262: PetscCall(PetscLogEventBegin(PETSC_BuildTwoSided, 0, 0, 0, 0));
263: PetscCall(PetscCommBuildTwoSidedGetType(comm, &buildtype));
264: switch (buildtype) {
265: case PETSC_BUILDTWOSIDED_IBARRIER:
266: #if defined(PETSC_HAVE_MPI_NONBLOCKING_COLLECTIVES)
267: PetscCall(PetscCommBuildTwoSided_Ibarrier(comm, count, dtype, nto, toranks, todata, nfrom, fromranks, fromdata));
268: break;
269: #else
270: SETERRQ(comm, PETSC_ERR_PLIB, "MPI implementation does not provide MPI_Ibarrier (part of MPI-3)");
271: #endif
272: case PETSC_BUILDTWOSIDED_ALLREDUCE:
273: PetscCall(PetscCommBuildTwoSided_Allreduce(comm, count, dtype, nto, toranks, todata, nfrom, fromranks, fromdata));
274: break;
275: case PETSC_BUILDTWOSIDED_REDSCATTER:
276: #if defined(PETSC_HAVE_MPI_REDUCE_SCATTER_BLOCK)
277: PetscCall(PetscCommBuildTwoSided_RedScatter(comm, count, dtype, nto, toranks, todata, nfrom, fromranks, fromdata));
278: break;
279: #else
280: SETERRQ(comm, PETSC_ERR_PLIB, "MPI implementation does not provide MPI_Reduce_scatter_block (part of MPI-2.2)");
281: #endif
282: default:
283: SETERRQ(comm, PETSC_ERR_PLIB, "Unknown method for building two-sided communication");
284: }
285: PetscCall(PetscLogEventEnd(PETSC_BuildTwoSided, 0, 0, 0, 0));
286: PetscFunctionReturn(PETSC_SUCCESS);
287: }
289: static PetscErrorCode PetscCommBuildTwoSidedFReq_Reference(MPI_Comm comm, PetscMPIInt count, MPI_Datatype dtype, PetscMPIInt nto, const PetscMPIInt *toranks, const void *todata, PetscMPIInt *nfrom, PetscMPIInt **fromranks, void *fromdata, PetscMPIInt ntags, MPI_Request **toreqs, MPI_Request **fromreqs, PetscErrorCode (*send)(MPI_Comm, const PetscMPIInt[], PetscMPIInt, PetscMPIInt, void *, MPI_Request[], void *), PetscErrorCode (*recv)(MPI_Comm, const PetscMPIInt[], PetscMPIInt, void *, MPI_Request[], void *), void *ctx)
290: {
291: PetscMPIInt i, *tag;
292: MPI_Aint lb, unitbytes;
293: MPI_Request *sendreq, *recvreq;
295: PetscFunctionBegin;
296: PetscCall(PetscMalloc1(ntags, &tag));
297: if (ntags > 0) PetscCall(PetscCommDuplicate(comm, &comm, &tag[0]));
298: for (i = 1; i < ntags; i++) PetscCall(PetscCommGetNewTag(comm, &tag[i]));
300: /* Perform complete initial rendezvous */
301: PetscCall(PetscCommBuildTwoSided(comm, count, dtype, nto, toranks, todata, nfrom, fromranks, fromdata));
303: PetscCall(PetscMalloc1(nto * ntags, &sendreq));
304: PetscCall(PetscMalloc1(*nfrom * ntags, &recvreq));
306: PetscCallMPI(MPI_Type_get_extent(dtype, &lb, &unitbytes));
307: PetscCheck(lb == 0, comm, PETSC_ERR_SUP, "Datatype with nonzero lower bound %ld", (long)lb);
308: for (i = 0; i < nto; i++) {
309: PetscMPIInt k;
310: for (k = 0; k < ntags; k++) sendreq[i * ntags + k] = MPI_REQUEST_NULL;
311: PetscCall((*send)(comm, tag, i, toranks[i], ((char *)todata) + count * unitbytes * i, sendreq + i * ntags, ctx));
312: }
313: for (i = 0; i < *nfrom; i++) {
314: void *header = (*(char **)fromdata) + count * unitbytes * i;
315: PetscMPIInt k;
316: for (k = 0; k < ntags; k++) recvreq[i * ntags + k] = MPI_REQUEST_NULL;
317: PetscCall((*recv)(comm, tag, (*fromranks)[i], header, recvreq + i * ntags, ctx));
318: }
319: PetscCall(PetscFree(tag));
320: PetscCall(PetscCommDestroy(&comm));
321: *toreqs = sendreq;
322: *fromreqs = recvreq;
323: PetscFunctionReturn(PETSC_SUCCESS);
324: }
326: #if defined(PETSC_HAVE_MPI_NONBLOCKING_COLLECTIVES)
328: static PetscErrorCode PetscCommBuildTwoSidedFReq_Ibarrier(MPI_Comm comm, PetscMPIInt count, MPI_Datatype dtype, PetscMPIInt nto, const PetscMPIInt *toranks, const void *todata, PetscMPIInt *nfrom, PetscMPIInt **fromranks, void *fromdata, PetscMPIInt ntags, MPI_Request **toreqs, MPI_Request **fromreqs, PetscErrorCode (*send)(MPI_Comm, const PetscMPIInt[], PetscMPIInt, PetscMPIInt, void *, MPI_Request[], void *), PetscErrorCode (*recv)(MPI_Comm, const PetscMPIInt[], PetscMPIInt, void *, MPI_Request[], void *), void *ctx)
329: {
330: PetscMPIInt nrecvs, tag, *tags, done, i;
331: MPI_Aint lb, unitbytes;
332: char *tdata;
333: MPI_Request *sendreqs, *usendreqs, *req, barrier;
334: PetscSegBuffer segrank, segdata, segreq;
335: PetscBool barrier_started;
337: PetscFunctionBegin;
338: PetscCall(PetscCommDuplicate(comm, &comm, &tag));
339: PetscCall(PetscMalloc1(ntags, &tags));
340: for (i = 0; i < ntags; i++) PetscCall(PetscCommGetNewTag(comm, &tags[i]));
341: PetscCallMPI(MPI_Type_get_extent(dtype, &lb, &unitbytes));
342: PetscCheck(lb == 0, comm, PETSC_ERR_SUP, "Datatype with nonzero lower bound %ld", (long)lb);
343: tdata = (char *)todata;
344: PetscCall(PetscMalloc1(nto, &sendreqs));
345: PetscCall(PetscMalloc1(nto * ntags, &usendreqs));
346: /* Post synchronous sends */
347: for (i = 0; i < nto; i++) PetscCallMPI(MPI_Issend((void *)(tdata + count * unitbytes * i), count, dtype, toranks[i], tag, comm, sendreqs + i));
348: /* Post actual payloads. These are typically larger messages. Hopefully sending these later does not slow down the
349: * synchronous messages above. */
350: for (i = 0; i < nto; i++) {
351: PetscMPIInt k;
352: for (k = 0; k < ntags; k++) usendreqs[i * ntags + k] = MPI_REQUEST_NULL;
353: PetscCall((*send)(comm, tags, i, toranks[i], tdata + count * unitbytes * i, usendreqs + i * ntags, ctx));
354: }
356: PetscCall(PetscSegBufferCreate(sizeof(PetscMPIInt), 4, &segrank));
357: PetscCall(PetscSegBufferCreate(unitbytes, 4 * count, &segdata));
358: PetscCall(PetscSegBufferCreate(sizeof(MPI_Request), 4, &segreq));
360: nrecvs = 0;
361: barrier = MPI_REQUEST_NULL;
362: /* MPICH-3.2 sometimes does not create a request in some "optimized" cases. This is arguably a standard violation,
363: * but we need to work around it. */
364: barrier_started = PETSC_FALSE;
365: for (done = 0; !done;) {
366: PetscMPIInt flag;
367: MPI_Status status;
368: PetscCallMPI(MPI_Iprobe(MPI_ANY_SOURCE, tag, comm, &flag, &status));
369: if (flag) { /* incoming message */
370: PetscMPIInt *recvrank, k;
371: void *buf;
372: PetscCall(PetscSegBufferGet(segrank, 1, &recvrank));
373: PetscCall(PetscSegBufferGet(segdata, count, &buf));
374: *recvrank = status.MPI_SOURCE;
375: PetscCallMPI(MPI_Recv(buf, count, dtype, status.MPI_SOURCE, tag, comm, MPI_STATUS_IGNORE));
376: PetscCall(PetscSegBufferGet(segreq, ntags, &req));
377: for (k = 0; k < ntags; k++) req[k] = MPI_REQUEST_NULL;
378: PetscCall((*recv)(comm, tags, status.MPI_SOURCE, buf, req, ctx));
379: nrecvs++;
380: }
381: if (!barrier_started) {
382: PetscMPIInt sent, nsends;
383: PetscCall(PetscMPIIntCast(nto, &nsends));
384: PetscCallMPI(MPI_Testall(nsends, sendreqs, &sent, MPI_STATUSES_IGNORE));
385: if (sent) {
386: PetscCallMPI(MPI_Ibarrier(comm, &barrier));
387: barrier_started = PETSC_TRUE;
388: }
389: } else {
390: PetscCallMPI(MPI_Test(&barrier, &done, MPI_STATUS_IGNORE));
391: }
392: }
393: *nfrom = nrecvs;
394: PetscCall(PetscSegBufferExtractAlloc(segrank, fromranks));
395: PetscCall(PetscSegBufferDestroy(&segrank));
396: PetscCall(PetscSegBufferExtractAlloc(segdata, fromdata));
397: PetscCall(PetscSegBufferDestroy(&segdata));
398: *toreqs = usendreqs;
399: PetscCall(PetscSegBufferExtractAlloc(segreq, fromreqs));
400: PetscCall(PetscSegBufferDestroy(&segreq));
401: PetscCall(PetscFree(sendreqs));
402: PetscCall(PetscFree(tags));
403: PetscCall(PetscCommDestroy(&comm));
404: PetscFunctionReturn(PETSC_SUCCESS);
405: }
406: #endif
408: /*@C
409: PetscCommBuildTwoSidedF - discovers communicating ranks given one-sided information, calling user-defined functions during rendezvous
411: Collective
413: Input Parameters:
414: + comm - communicator
415: . count - number of entries to send/receive in initial rendezvous (must match on all ranks)
416: . dtype - datatype to send/receive from each rank (must match on all ranks)
417: . nto - number of ranks to send data to
418: . toranks - ranks to send to (array of length nto)
419: . todata - data to send to each rank (packed)
420: . ntags - number of tags needed by send/recv callbacks
421: . send - callback invoked on sending process when ready to send primary payload
422: . recv - callback invoked on receiving process after delivery of rendezvous message
423: - ctx - context for callbacks
425: Output Parameters:
426: + nfrom - number of ranks receiving messages from
427: . fromranks - ranks receiving messages from (length nfrom; caller should `PetscFree()`)
428: - fromdata - packed data from each rank, each with count entries of type dtype (length nfrom, caller responsible for `PetscFree()`)
430: Level: developer
432: Notes:
433: This memory-scalable interface is an alternative to calling `PetscGatherNumberOfMessages()` and
434: `PetscGatherMessageLengths()`, possibly with a subsequent round of communication to send other data, {cite}`hoeflersiebretlumsdaine10`.
436: Basic data types as well as contiguous types are supported, but non-contiguous (e.g., strided) types are not.
438: .seealso: `PetscCommBuildTwoSided()`, `PetscCommBuildTwoSidedFReq()`, `PetscGatherNumberOfMessages()`, `PetscGatherMessageLengths()`
439: @*/
440: PetscErrorCode PetscCommBuildTwoSidedF(MPI_Comm comm, PetscMPIInt count, MPI_Datatype dtype, PetscMPIInt nto, const PetscMPIInt *toranks, const void *todata, PetscMPIInt *nfrom, PetscMPIInt **fromranks, void *fromdata, PetscMPIInt ntags, PetscErrorCode (*send)(MPI_Comm, const PetscMPIInt[], PetscMPIInt, PetscMPIInt, void *, MPI_Request[], void *), PetscErrorCode (*recv)(MPI_Comm, const PetscMPIInt[], PetscMPIInt, void *, MPI_Request[], void *), void *ctx)
441: {
442: MPI_Request *toreqs, *fromreqs;
444: PetscFunctionBegin;
445: PetscCall(PetscCommBuildTwoSidedFReq(comm, count, dtype, nto, toranks, todata, nfrom, fromranks, fromdata, ntags, &toreqs, &fromreqs, send, recv, ctx));
446: PetscCallMPI(MPI_Waitall(nto * ntags, toreqs, MPI_STATUSES_IGNORE));
447: PetscCallMPI(MPI_Waitall(*nfrom * ntags, fromreqs, MPI_STATUSES_IGNORE));
448: PetscCall(PetscFree(toreqs));
449: PetscCall(PetscFree(fromreqs));
450: PetscFunctionReturn(PETSC_SUCCESS);
451: }
453: /*@C
454: PetscCommBuildTwoSidedFReq - discovers communicating ranks given one-sided information, calling user-defined functions during rendezvous, returns requests
456: Collective
458: Input Parameters:
459: + comm - communicator
460: . count - number of entries to send/receive in initial rendezvous (must match on all ranks)
461: . dtype - datatype to send/receive from each rank (must match on all ranks)
462: . nto - number of ranks to send data to
463: . toranks - ranks to send to (array of length nto)
464: . todata - data to send to each rank (packed)
465: . ntags - number of tags needed by send/recv callbacks
466: . send - callback invoked on sending process when ready to send primary payload
467: . recv - callback invoked on receiving process after delivery of rendezvous message
468: - ctx - context for callbacks
470: Output Parameters:
471: + nfrom - number of ranks receiving messages from
472: . fromranks - ranks receiving messages from (length nfrom; caller should `PetscFree()`)
473: . fromdata - packed data from each rank, each with count entries of type dtype (length nfrom, caller responsible for `PetscFree()`)
474: . toreqs - array of nto*ntags sender requests (caller must wait on these, then `PetscFree()`)
475: - fromreqs - array of nfrom*ntags receiver requests (caller must wait on these, then `PetscFree()`)
477: Level: developer
479: Notes:
480: This memory-scalable interface is an alternative to calling `PetscGatherNumberOfMessages()` and
481: `PetscGatherMessageLengths()`, possibly with a subsequent round of communication to send other data, {cite}`hoeflersiebretlumsdaine10`.
483: Basic data types as well as contiguous types are supported, but non-contiguous (e.g., strided) types are not.
485: .seealso: `PetscCommBuildTwoSided()`, `PetscCommBuildTwoSidedF()`, `PetscGatherNumberOfMessages()`, `PetscGatherMessageLengths()`
486: @*/
487: PetscErrorCode PetscCommBuildTwoSidedFReq(MPI_Comm comm, PetscMPIInt count, MPI_Datatype dtype, PetscMPIInt nto, const PetscMPIInt *toranks, const void *todata, PetscMPIInt *nfrom, PetscMPIInt **fromranks, void *fromdata, PetscMPIInt ntags, MPI_Request **toreqs, MPI_Request **fromreqs, PetscErrorCode (*send)(MPI_Comm, const PetscMPIInt[], PetscMPIInt, PetscMPIInt, void *, MPI_Request[], void *), PetscErrorCode (*recv)(MPI_Comm, const PetscMPIInt[], PetscMPIInt, void *, MPI_Request[], void *), void *ctx)
488: {
489: PetscErrorCode (*f)(MPI_Comm, PetscMPIInt, MPI_Datatype, PetscMPIInt, const PetscMPIInt[], const void *, PetscMPIInt *, PetscMPIInt **, void *, PetscMPIInt, MPI_Request **, MPI_Request **, PetscErrorCode (*send)(MPI_Comm, const PetscMPIInt[], PetscMPIInt, PetscMPIInt, void *, MPI_Request[], void *), PetscErrorCode (*recv)(MPI_Comm, const PetscMPIInt[], PetscMPIInt, void *, MPI_Request[], void *), void *ctx);
490: PetscBuildTwoSidedType buildtype = PETSC_BUILDTWOSIDED_NOTSET;
491: PetscMPIInt i, size;
493: PetscFunctionBegin;
494: PetscCall(PetscSysInitializePackage());
495: PetscCallMPI(MPI_Comm_size(comm, &size));
496: for (i = 0; i < nto; i++) PetscCheck(toranks[i] >= 0 && size > toranks[i], comm, PETSC_ERR_ARG_OUTOFRANGE, "toranks[%d] %d not in comm size %d", i, toranks[i], size);
497: PetscCall(PetscLogEventSync(PETSC_BuildTwoSidedF, comm));
498: PetscCall(PetscLogEventBegin(PETSC_BuildTwoSidedF, 0, 0, 0, 0));
499: PetscCall(PetscCommBuildTwoSidedGetType(comm, &buildtype));
500: switch (buildtype) {
501: case PETSC_BUILDTWOSIDED_IBARRIER:
502: #if defined(PETSC_HAVE_MPI_NONBLOCKING_COLLECTIVES)
503: f = PetscCommBuildTwoSidedFReq_Ibarrier;
504: break;
505: #else
506: SETERRQ(comm, PETSC_ERR_PLIB, "MPI implementation does not provide MPI_Ibarrier (part of MPI-3)");
507: #endif
508: case PETSC_BUILDTWOSIDED_ALLREDUCE:
509: case PETSC_BUILDTWOSIDED_REDSCATTER:
510: f = PetscCommBuildTwoSidedFReq_Reference;
511: break;
512: default:
513: SETERRQ(comm, PETSC_ERR_PLIB, "Unknown method for building two-sided communication");
514: }
515: PetscCall((*f)(comm, count, dtype, nto, toranks, todata, nfrom, fromranks, fromdata, ntags, toreqs, fromreqs, send, recv, ctx));
516: PetscCall(PetscLogEventEnd(PETSC_BuildTwoSidedF, 0, 0, 0, 0));
517: PetscFunctionReturn(PETSC_SUCCESS);
518: }