Actual source code: tagm.c
petsc-3.10.5 2019-03-28
2: /*
3: Some PETSc utilites
4: */
5: #include <petsc/private/petscimpl.h>
6: /* ---------------------------------------------------------------- */
7: /*
8: A simple way to manage tags inside a communicator.
10: It uses the attributes to determine if a new communicator
11: is needed and to store the available tags.
13: */
16: /*@C
17: PetscObjectGetNewTag - Gets a unique new tag from a PETSc object. All
18: processors that share the object MUST call this routine EXACTLY the same
19: number of times. This tag should only be used with the current objects
20: communicator; do NOT use it with any other MPI communicator.
22: Collective on PetscObject
24: Input Parameter:
25: . obj - the PETSc object; this must be cast with a (PetscObject), for example,
26: PetscObjectGetNewTag((PetscObject)mat,&tag);
28: Output Parameter:
29: . tag - the new tag
31: Level: developer
33: Concepts: tag^getting
34: Concepts: message tag^getting
35: Concepts: MPI message tag^getting
37: .seealso: PetscCommGetNewTag()
38: @*/
39: PetscErrorCode PetscObjectGetNewTag(PetscObject obj,PetscMPIInt *tag)
40: {
44: PetscCommGetNewTag(obj->comm,tag);
45: return(0);
46: }
48: /*@
49: PetscCommGetNewTag - Gets a unique new tag from a PETSc communicator. All
50: processors that share the communicator MUST call this routine EXACTLY the same
51: number of times. This tag should only be used with the current objects
52: communicator; do NOT use it with any other MPI communicator.
54: Collective on comm
56: Input Parameter:
57: . comm - the MPI communicator
59: Output Parameter:
60: . tag - the new tag
62: Level: developer
64: Concepts: tag^getting
65: Concepts: message tag^getting
66: Concepts: MPI message tag^getting
68: .seealso: PetscObjectGetNewTag(), PetscCommDuplicate()
69: @*/
70: PetscErrorCode PetscCommGetNewTag(MPI_Comm comm,PetscMPIInt *tag)
71: {
72: PetscErrorCode ierr;
73: PetscCommCounter *counter;
74: PetscMPIInt *maxval,flg;
79: MPI_Comm_get_attr(comm,Petsc_Counter_keyval,&counter,&flg);
80: if (!flg) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_CORRUPT,"Bad MPI communicator supplied; must be a PETSc communicator");
82: if (counter->tag < 1) {
83: PetscInfo1(0,"Out of tags for object, starting to recycle. Comm reference count %d\n",counter->refcount);
84: MPI_Comm_get_attr(MPI_COMM_WORLD,MPI_TAG_UB,&maxval,&flg);
85: if (!flg) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_LIB,"MPI error: MPI_Comm_get_attr() is not returning a MPI_TAG_UB");
86: counter->tag = *maxval - 128; /* hope that any still active tags were issued right at the beginning of the run */
87: }
89: *tag = counter->tag--;
90: #if defined(PETSC_USE_DEBUG)
91: /*
92: Hanging here means that some processes have called PetscCommGetNewTag() and others have not.
93: */
94: MPI_Barrier(comm);
95: #endif
96: return(0);
97: }
99: /*@C
100: PetscCommDuplicate - Duplicates the communicator only if it is not already a PETSc communicator.
102: Collective on MPI_Comm
104: Input Parameters:
105: . comm_in - Input communicator
107: Output Parameters:
108: + comm_out - Output communicator. May be comm_in.
109: - first_tag - Tag available that has not already been used with this communicator (you may
110: pass in NULL if you do not need a tag)
112: PETSc communicators are just regular MPI communicators that keep track of which
113: tags have been used to prevent tag conflict. If you pass a non-PETSc communicator into
114: a PETSc creation routine it will attach a private communicator for use in the objects communications.
115: The internal MPI_Comm is used to perform all the MPI calls for PETSc, the outer MPI_Comm is a user
116: level MPI_Comm that may be performing communication for the user or other library and so IS NOT used by PETSc.
118: Level: developer
120: Concepts: communicator^duplicate
122: .seealso: PetscObjectGetNewTag(), PetscCommGetNewTag(), PetscCommDestroy()
123: @*/
124: PetscErrorCode PetscCommDuplicate(MPI_Comm comm_in,MPI_Comm *comm_out,PetscMPIInt *first_tag)
125: {
126: PetscErrorCode ierr;
127: PetscCommCounter *counter;
128: PetscMPIInt *maxval,flg;
131: PetscSpinlockLock(&PetscCommSpinLock);
132: MPI_Comm_get_attr(comm_in,Petsc_Counter_keyval,&counter,&flg);
134: if (!flg) { /* this is NOT a PETSc comm */
135: union {MPI_Comm comm; void *ptr;} ucomm;
136: /* check if this communicator has a PETSc communicator imbedded in it */
137: MPI_Comm_get_attr(comm_in,Petsc_InnerComm_keyval,&ucomm,&flg);
138: if (!flg) {
139: /* This communicator is not yet known to this system, so we duplicate it and make an internal communicator */
140: MPI_Comm_dup(comm_in,comm_out);
141: MPI_Comm_get_attr(MPI_COMM_WORLD,MPI_TAG_UB,&maxval,&flg);
142: if (!flg) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_LIB,"MPI error: MPI_Comm_get_attr() is not returning a MPI_TAG_UB");
143: PetscNew(&counter);
145: counter->tag = *maxval;
146: counter->refcount = 0;
147: counter->namecount = 0;
149: MPI_Comm_set_attr(*comm_out,Petsc_Counter_keyval,counter);
150: PetscInfo3(0,"Duplicating a communicator %ld %ld max tags = %d\n",(long)comm_in,(long)*comm_out,*maxval);
152: /* save PETSc communicator inside user communicator, so we can get it next time */
153: ucomm.comm = *comm_out; /* ONLY the comm part of the union is significant. */
154: MPI_Comm_set_attr(comm_in,Petsc_InnerComm_keyval,ucomm.ptr);
155: ucomm.comm = comm_in;
156: MPI_Comm_set_attr(*comm_out,Petsc_OuterComm_keyval,ucomm.ptr);
157: } else {
158: *comm_out = ucomm.comm;
159: /* pull out the inner MPI_Comm and hand it back to the caller */
160: MPI_Comm_get_attr(*comm_out,Petsc_Counter_keyval,&counter,&flg);
161: if (!flg) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_PLIB,"Inner PETSc communicator does not have its tag/name counter attribute set");
162: PetscInfo2(0,"Using internal PETSc communicator %ld %ld\n",(long)comm_in,(long)*comm_out);
163: }
164: } else *comm_out = comm_in;
166: #if defined(PETSC_USE_DEBUG)
167: /*
168: Hanging here means that some processes have called PetscCommDuplicate() and others have not.
169: This likley means that a subset of processes in a MPI_Comm have attempted to create a PetscObject!
170: ALL processes that share a communicator MUST shared objects created from that communicator.
171: */
172: MPI_Barrier(comm_in);
173: #endif
175: if (counter->tag < 1) {
176: PetscInfo1(0,"Out of tags for object, starting to recycle. Comm reference count %d\n",counter->refcount);
177: MPI_Comm_get_attr(MPI_COMM_WORLD,MPI_TAG_UB,&maxval,&flg);
178: if (!flg) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_LIB,"MPI error: MPI_Comm_get_attr() is not returning a MPI_TAG_UB");
179: counter->tag = *maxval - 128; /* hope that any still active tags were issued right at the beginning of the run */
180: }
182: if (first_tag) *first_tag = counter->tag--;
184: counter->refcount++; /* number of references to this comm */
185: PetscSpinlockUnlock(&PetscCommSpinLock);
186: return(0);
187: }
189: /*@C
190: PetscCommDestroy - Frees communicator. Use in conjunction with PetscCommDuplicate().
192: Collective on MPI_Comm
194: Input Parameter:
195: . comm - the communicator to free
197: Level: developer
199: Concepts: communicator^destroy
201: .seealso: PetscCommDuplicate()
202: @*/
203: PetscErrorCode PetscCommDestroy(MPI_Comm *comm)
204: {
205: PetscErrorCode ierr;
206: PetscCommCounter *counter;
207: PetscMPIInt flg;
208: MPI_Comm icomm = *comm,ocomm;
209: union {MPI_Comm comm; void *ptr;} ucomm;
212: if (*comm == MPI_COMM_NULL) return(0);
213: PetscSpinlockLock(&PetscCommSpinLock);
214: MPI_Comm_get_attr(icomm,Petsc_Counter_keyval,&counter,&flg);
215: if (!flg) { /* not a PETSc comm, check if it has an inner comm */
216: MPI_Comm_get_attr(icomm,Petsc_InnerComm_keyval,&ucomm,&flg);
217: if (!flg) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_CORRUPT,"MPI_Comm does not have tag/name counter nor does it have inner MPI_Comm");
218: icomm = ucomm.comm;
219: MPI_Comm_get_attr(icomm,Petsc_Counter_keyval,&counter,&flg);
220: if (!flg) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_CORRUPT,"Inner MPI_Comm does not have expected tag/name counter, problem with corrupted memory");
221: }
223: counter->refcount--;
225: if (!counter->refcount) {
226: /* if MPI_Comm has outer comm then remove reference to inner MPI_Comm from outer MPI_Comm */
227: MPI_Comm_get_attr(icomm,Petsc_OuterComm_keyval,&ucomm,&flg);
228: if (flg) {
229: ocomm = ucomm.comm;
230: MPI_Comm_get_attr(ocomm,Petsc_InnerComm_keyval,&ucomm,&flg);
231: if (flg) {
232: MPI_Comm_delete_attr(ocomm,Petsc_InnerComm_keyval);
233: } else SETERRQ2(PETSC_COMM_SELF,PETSC_ERR_ARG_CORRUPT,"Outer MPI_Comm %ld does not have expected reference to inner comm %d, problem with corrupted memory",(long int)ocomm,(long int)icomm);
234: }
236: PetscInfo1(0,"Deleting PETSc MPI_Comm %ld\n",(long)icomm);
237: MPI_Comm_free(&icomm);
238: }
239: *comm = MPI_COMM_NULL;
240: PetscSpinlockUnlock(&PetscCommSpinLock);
241: return(0);
242: }
244: /*@C
245: PetscObjectsListGetGlobalNumbering - computes a global numbering
246: of PetscObjects living on subcommunicators of a given communicator.
249: Collective on comm.
251: Input Parameters:
252: + comm - MPI_Comm
253: . len - local length of objlist
254: - objlist - a list of PETSc objects living on subcomms of comm and containing this comm rank
255: (subcomm ordering is assumed to be deadlock-free)
257: Output Parameters:
258: + count - global number of distinct subcommunicators on objlist (may be > len)
259: - numbering - global numbers of objlist entries (allocated by user)
262: Level: developer
264: Concepts: MPI subcomm^numbering
266: @*/
267: PetscErrorCode PetscObjectsListGetGlobalNumbering(MPI_Comm comm, PetscInt len, PetscObject *objlist, PetscInt *count, PetscInt *numbering)
268: {
270: PetscInt i, roots, offset;
271: PetscMPIInt size, rank;
275: if (!count && !numbering) return(0);
277: MPI_Comm_size(comm, &size);
278: MPI_Comm_rank(comm, &rank);
279: roots = 0;
280: for (i = 0; i < len; ++i) {
281: PetscMPIInt srank;
282: MPI_Comm_rank(objlist[i]->comm, &srank);
283: /* Am I the root of the i-th subcomm? */
284: if (!srank) ++roots;
285: }
286: if (count) {
287: /* Obtain the sum of all roots -- the global number of distinct subcomms. */
288: MPIU_Allreduce(&roots,count,1,MPIU_INT,MPI_SUM,comm);
289: }
290: if (numbering){
291: /* Introduce a global numbering for subcomms, initially known only by subcomm roots. */
292: /*
293: At each subcomm root number all of the subcomms it owns locally
294: and make it global by calculating the shift among all of the roots.
295: The roots are ordered using the comm ordering.
296: */
297: MPI_Scan(&roots,&offset,1,MPIU_INT,MPI_SUM,comm);
298: offset -= roots;
299: /* Now we are ready to broadcast global subcomm numbers within each subcomm.*/
300: /*
301: This is where the assumption of a deadlock-free ordering of the subcomms is assumed:
302: broadcast is collective on the subcomm.
303: */
304: roots = 0;
305: for (i = 0; i < len; ++i) {
306: PetscMPIInt srank;
307: numbering[i] = offset + roots; /* only meaningful if !srank. */
309: MPI_Comm_rank(objlist[i]->comm, &srank);
310: MPI_Bcast(numbering+i,1,MPIU_INT,0,objlist[i]->comm);
311: if (!srank) ++roots;
312: }
313: }
314: return(0);
315: }