Actual source code: vecstash.c
1: #define PETSCVEC_DLL
3: #include vecimpl.h
5: #define DEFAULT_STASH_SIZE 100
7: /*
8: VecStashCreate_Private - Creates a stash,currently used for all the parallel
9: matrix implementations. The stash is where elements of a matrix destined
10: to be stored on other processors are kept until matrix assembly is done.
12: This is a simple minded stash. Simply adds entries to end of stash.
14: Input Parameters:
15: comm - communicator, required for scatters.
16: bs - stash block size. used when stashing blocks of values
18: Output Parameters:
19: stash - the newly created stash
20: */
23: PetscErrorCode VecStashCreate_Private(MPI_Comm comm,PetscInt bs,VecStash *stash)
24: {
26: PetscInt max,*opt,nopt;
27: PetscTruth flg;
30: /* Require 2 tags, get the second using PetscCommGetNewTag() */
31: stash->comm = comm;
32: PetscCommGetNewTag(stash->comm,&stash->tag1);
33: PetscCommGetNewTag(stash->comm,&stash->tag2);
34: MPI_Comm_size(stash->comm,&stash->size);
35: MPI_Comm_rank(stash->comm,&stash->rank);
37: nopt = stash->size;
38: PetscMalloc(nopt*sizeof(PetscInt),&opt);
39: PetscOptionsGetIntArray(PETSC_NULL,"-vecstash_initial_size",opt,&nopt,&flg);
40: if (flg) {
41: if (nopt == 1) max = opt[0];
42: else if (nopt == stash->size) max = opt[stash->rank];
43: else if (stash->rank < nopt) max = opt[stash->rank];
44: else max = 0; /* use default */
45: stash->umax = max;
46: } else {
47: stash->umax = 0;
48: }
49: PetscFree(opt);
51: if (bs <= 0) bs = 1;
53: stash->bs = bs;
54: stash->nmax = 0;
55: stash->oldnmax = 0;
56: stash->n = 0;
57: stash->reallocs = -1;
58: stash->idx = 0;
59: stash->array = 0;
61: stash->send_waits = 0;
62: stash->recv_waits = 0;
63: stash->send_status = 0;
64: stash->nsends = 0;
65: stash->nrecvs = 0;
66: stash->svalues = 0;
67: stash->rvalues = 0;
68: stash->rmax = 0;
69: stash->nprocs = 0;
70: stash->nprocessed = 0;
71: stash->donotstash = PETSC_FALSE;
72: return(0);
73: }
75: /*
76: VecStashDestroy_Private - Destroy the stash
77: */
80: PetscErrorCode VecStashDestroy_Private(VecStash *stash)
81: {
85: if (stash->array) {
86: PetscFree(stash->array);
87: stash->array = 0;
88: }
89: if (stash->bowners) {
90: PetscFree(stash->bowners);
91: }
92: return(0);
93: }
95: /*
96: VecStashScatterEnd_Private - This is called as the fial stage of
97: scatter. The final stages of message passing is done here, and
98: all the memory used for message passing is cleanedu up. This
99: routine also resets the stash, and deallocates the memory used
100: for the stash. It also keeps track of the current memory usage
101: so that the same value can be used the next time through.
102: */
105: PetscErrorCode VecStashScatterEnd_Private(VecStash *stash)
106: {
108: PetscInt nsends=stash->nsends,oldnmax;
109: MPI_Status *send_status;
112: /* wait on sends */
113: if (nsends) {
114: PetscMalloc(2*nsends*sizeof(MPI_Status),&send_status);
115: MPI_Waitall(2*nsends,stash->send_waits,send_status);
116: PetscFree(send_status);
117: }
119: /* Now update nmaxold to be app 10% more than max n, this way the
120: wastage of space is reduced the next time this stash is used.
121: Also update the oldmax, only if it increases */
122: if (stash->n) {
123: oldnmax = ((PetscInt)(stash->n * 1.1) + 5)*stash->bs;
124: if (oldnmax > stash->oldnmax) stash->oldnmax = oldnmax;
125: }
127: stash->nmax = 0;
128: stash->n = 0;
129: stash->reallocs = -1;
130: stash->rmax = 0;
131: stash->nprocessed = 0;
133: if (stash->array) {
134: PetscFree(stash->array);
135: stash->array = 0;
136: stash->idx = 0;
137: }
138: if (stash->send_waits) {
139: PetscFree(stash->send_waits);
140: stash->send_waits = 0;
141: }
142: if (stash->recv_waits) {
143: PetscFree(stash->recv_waits);
144: stash->recv_waits = 0;
145: }
146: if (stash->svalues) {
147: PetscFree(stash->svalues);
148: stash->svalues = 0;
149: }
150: if (stash->rvalues) {
151: PetscFree(stash->rvalues);
152: stash->rvalues = 0;
153: }
154: if (stash->nprocs) {
155: PetscFree(stash->nprocs);
156: stash->nprocs = 0;
157: }
158: return(0);
159: }
161: /*
162: VecStashGetInfo_Private - Gets the relavant statistics of the stash
164: Input Parameters:
165: stash - the stash
166: nstash - the size of the stash
167: reallocs - the number of additional mallocs incurred.
168:
169: */
172: PetscErrorCode VecStashGetInfo_Private(VecStash *stash,PetscInt *nstash,PetscInt *reallocs)
173: {
176: if (nstash) *nstash = stash->n*stash->bs;
177: if (reallocs) {
178: if (stash->reallocs < 0) *reallocs = 0;
179: else *reallocs = stash->reallocs;
180: }
181: return(0);
182: }
185: /*
186: VecStashSetInitialSize_Private - Sets the initial size of the stash
188: Input Parameters:
189: stash - the stash
190: max - the value that is used as the max size of the stash.
191: this value is used while allocating memory. It specifies
192: the number of vals stored, even with the block-stash
193: */
196: PetscErrorCode VecStashSetInitialSize_Private(VecStash *stash,PetscInt max)
197: {
199: stash->umax = max;
200: return(0);
201: }
203: /* VecStashExpand_Private - Expand the stash. This function is called
204: when the space in the stash is not sufficient to add the new values
205: being inserted into the stash.
206:
207: Input Parameters:
208: stash - the stash
209: incr - the minimum increase requested
210:
211: Notes:
212: This routine doubles the currently used memory.
213: */
216: PetscErrorCode VecStashExpand_Private(VecStash *stash,PetscInt incr)
217: {
219: PetscInt *n_idx,newnmax,bs=stash->bs;
220: PetscScalar *n_array;
223: /* allocate a larger stash. */
224: if (!stash->oldnmax && !stash->nmax) { /* new stash */
225: if (stash->umax) newnmax = stash->umax/bs;
226: else newnmax = DEFAULT_STASH_SIZE/bs;
227: } else if (!stash->nmax) { /* resuing stash */
228: if (stash->umax > stash->oldnmax) newnmax = stash->umax/bs;
229: else newnmax = stash->oldnmax/bs;
230: } else newnmax = stash->nmax*2;
232: if (newnmax < (stash->nmax + incr)) newnmax += 2*incr;
234: PetscMalloc((newnmax)*(sizeof(PetscInt)+bs*sizeof(PetscScalar)),&n_array);
235: n_idx = (PetscInt*)(n_array + bs*newnmax);
236: PetscMemcpy(n_array,stash->array,bs*stash->nmax*sizeof(PetscScalar));
237: PetscMemcpy(n_idx,stash->idx,stash->nmax*sizeof(PetscInt));
238: if (stash->array) {PetscFree(stash->array);}
239: stash->array = n_array;
240: stash->idx = n_idx;
241: stash->nmax = newnmax;
242: stash->reallocs++;
243: return(0);
244: }
245: /*
246: VecStashScatterBegin_Private - Initiates the transfer of values to the
247: correct owners. This function goes through the stash, and check the
248: owners of each stashed value, and sends the values off to the owner
249: processors.
251: Input Parameters:
252: stash - the stash
253: owners - an array of size 'no-of-procs' which gives the ownership range
254: for each node.
256: Notes: The 'owners' array in the cased of the blocked-stash has the
257: ranges specified blocked global indices, and for the regular stash in
258: the proper global indices.
259: */
262: PetscErrorCode VecStashScatterBegin_Private(VecStash *stash,PetscInt *owners)
263: {
265: PetscMPIInt size = stash->size,tag1=stash->tag1,tag2=stash->tag2;
266: PetscInt *owner,*start,*nprocs,nsends,nreceives;
267: PetscInt nmax,count,*sindices,*rindices,i,j,idx,bs=stash->bs,lastidx;
268: PetscScalar *rvalues,*svalues;
269: MPI_Comm comm = stash->comm;
270: MPI_Request *send_waits,*recv_waits;
274: /* first count number of contributors to each processor */
275: PetscMalloc(2*size*sizeof(PetscInt),&nprocs);
276: PetscMemzero(nprocs,2*size*sizeof(PetscInt));
277: PetscMalloc((stash->n+1)*sizeof(PetscInt),&owner);
279: j = 0;
280: lastidx = -1;
281: for (i=0; i<stash->n; i++) {
282: /* if indices are NOT locally sorted, need to start search at the beginning */
283: if (lastidx > (idx = stash->idx[i])) j = 0;
284: lastidx = idx;
285: for (; j<size; j++) {
286: if (idx >= owners[j] && idx < owners[j+1]) {
287: nprocs[2*j]++; nprocs[2*j+1] = 1; owner[i] = j; break;
288: }
289: }
290: }
291: nsends = 0; for (i=0; i<size; i++) { nsends += nprocs[2*i+1];}
292:
293: /* inform other processors of number of messages and max length*/
294: PetscMaxSum(comm,nprocs,&nmax,&nreceives);
296: /* post receives:
297: since we don't know how long each individual message is we
298: allocate the largest needed buffer for each receive. Potentially
299: this is a lot of wasted space.
300: */
301: PetscMalloc((nreceives+1)*(nmax+1)*(bs*sizeof(PetscScalar)+sizeof(PetscInt)),&rvalues);
302: rindices = (PetscInt*)(rvalues + bs*nreceives*nmax);
303: PetscMalloc((nreceives+1)*2*sizeof(MPI_Request),&recv_waits);
304: for (i=0,count=0; i<nreceives; i++) {
305: MPI_Irecv(rvalues+bs*nmax*i,bs*nmax,MPIU_SCALAR,MPI_ANY_SOURCE,tag1,comm,recv_waits+count++);
306: MPI_Irecv(rindices+nmax*i,nmax,MPIU_INT,MPI_ANY_SOURCE,tag2,comm,recv_waits+count++);
307: }
309: /* do sends:
310: 1) starts[i] gives the starting index in svalues for stuff going to
311: the ith processor
312: */
313: PetscMalloc((stash->n+1)*(bs*sizeof(PetscScalar)+sizeof(PetscInt)),&svalues);
314: sindices = (PetscInt*)(svalues + bs*stash->n);
315: PetscMalloc(2*(nsends+1)*sizeof(MPI_Request),&send_waits);
316: PetscMalloc(size*sizeof(PetscInt),&start);
317: /* use 2 sends the first with all_v, the next with all_i */
318: start[0] = 0;
319: for (i=1; i<size; i++) {
320: start[i] = start[i-1] + nprocs[2*i-2];
321: }
322: for (i=0; i<stash->n; i++) {
323: j = owner[i];
324: if (bs == 1) {
325: svalues[start[j]] = stash->array[i];
326: } else {
327: PetscMemcpy(svalues+bs*start[j],stash->array+bs*i,bs*sizeof(PetscScalar));
328: }
329: sindices[start[j]] = stash->idx[i];
330: start[j]++;
331: }
332: start[0] = 0;
333: for (i=1; i<size; i++) { start[i] = start[i-1] + nprocs[2*i-2];}
334: for (i=0,count=0; i<size; i++) {
335: if (nprocs[2*i+1]) {
336: MPI_Isend(svalues+bs*start[i],bs*nprocs[2*i],MPIU_SCALAR,i,tag1,comm,send_waits+count++);
337: MPI_Isend(sindices+start[i],nprocs[2*i],MPIU_INT,i,tag2,comm,send_waits+count++);
338: }
339: }
340: PetscFree(owner);
341: PetscFree(start);
342: /* This memory is reused in scatter end for a different purpose*/
343: for (i=0; i<2*size; i++) nprocs[i] = -1;
344: stash->nprocs = nprocs;
346: stash->svalues = svalues; stash->rvalues = rvalues;
347: stash->nsends = nsends; stash->nrecvs = nreceives;
348: stash->send_waits = send_waits; stash->recv_waits = recv_waits;
349: stash->rmax = nmax;
350: return(0);
351: }
353: /*
354: VecStashScatterGetMesg_Private - This function waits on the receives posted
355: in the function VecStashScatterBegin_Private() and returns one message at
356: a time to the calling function. If no messages are left, it indicates this
357: by setting flg = 0, else it sets flg = 1.
359: Input Parameters:
360: stash - the stash
362: Output Parameters:
363: nvals - the number of entries in the current message.
364: rows - an array of row indices (or blocked indices) corresponding to the values
365: cols - an array of columnindices (or blocked indices) corresponding to the values
366: vals - the values
367: flg - 0 indicates no more message left, and the current call has no values associated.
368: 1 indicates that the current call successfully received a message, and the
369: other output parameters nvals,rows,cols,vals are set appropriately.
370: */
373: PetscErrorCode VecStashScatterGetMesg_Private(VecStash *stash,PetscMPIInt *nvals,PetscInt **rows,PetscScalar **vals,PetscInt *flg)
374: {
376: PetscMPIInt i;
377: PetscInt *flg_v;
378: PetscInt i1,i2,*rindices,bs=stash->bs;
379: MPI_Status recv_status;
380: PetscTruth match_found = PETSC_FALSE;
384: *flg = 0; /* When a message is discovered this is reset to 1 */
385: /* Return if no more messages to process */
386: if (stash->nprocessed == stash->nrecvs) { return(0); }
388: flg_v = stash->nprocs;
389: /* If a matching pair of receieves are found, process them, and return the data to
390: the calling function. Until then keep receiving messages */
391: while (!match_found) {
392: MPI_Waitany(2*stash->nrecvs,stash->recv_waits,&i,&recv_status);
393: /* Now pack the received message into a structure which is useable by others */
394: if (i % 2) {
395: MPI_Get_count(&recv_status,MPIU_INT,nvals);
396: flg_v[2*recv_status.MPI_SOURCE+1] = i/2;
397: } else {
398: MPI_Get_count(&recv_status,MPIU_SCALAR,nvals);
399: flg_v[2*recv_status.MPI_SOURCE] = i/2;
400: *nvals = *nvals/bs;
401: }
402:
403: /* Check if we have both the messages from this proc */
404: i1 = flg_v[2*recv_status.MPI_SOURCE];
405: i2 = flg_v[2*recv_status.MPI_SOURCE+1];
406: if (i1 != -1 && i2 != -1) {
407: rindices = (PetscInt*)(stash->rvalues + bs*stash->rmax*stash->nrecvs);
408: *rows = rindices + i2*stash->rmax;
409: *vals = stash->rvalues + i1*bs*stash->rmax;
410: *flg = 1;
411: stash->nprocessed ++;
412: match_found = PETSC_TRUE;
413: }
414: }
415: return(0);
416: }