Actual source code: vecstash.c
2: #include <private/vecimpl.h>
4: #define DEFAULT_STASH_SIZE 100
6: /*
7: VecStashCreate_Private - Creates a stash,currently used for all the parallel
8: matrix implementations. The stash is where elements of a matrix destined
9: to be stored on other processors are kept until matrix assembly is done.
11: This is a simple minded stash. Simply adds entries to end of stash.
13: Input Parameters:
14: comm - communicator, required for scatters.
15: bs - stash block size. used when stashing blocks of values
17: Output Parameters:
18: stash - the newly created stash
19: */
22: PetscErrorCode VecStashCreate_Private(MPI_Comm comm,PetscInt bs,VecStash *stash)
23: {
25: PetscInt max,*opt,nopt;
26: PetscBool flg;
29: /* Require 2 tags, get the second using PetscCommGetNewTag() */
30: stash->comm = comm;
31: PetscCommGetNewTag(stash->comm,&stash->tag1);
32: PetscCommGetNewTag(stash->comm,&stash->tag2);
33: MPI_Comm_size(stash->comm,&stash->size);
34: MPI_Comm_rank(stash->comm,&stash->rank);
36: nopt = stash->size;
37: PetscMalloc(nopt*sizeof(PetscInt),&opt);
38: PetscOptionsGetIntArray(PETSC_NULL,"-vecstash_initial_size",opt,&nopt,&flg);
39: if (flg) {
40: if (nopt == 1) max = opt[0];
41: else if (nopt == stash->size) max = opt[stash->rank];
42: else if (stash->rank < nopt) max = opt[stash->rank];
43: else max = 0; /* use default */
44: stash->umax = max;
45: } else {
46: stash->umax = 0;
47: }
48: PetscFree(opt);
50: if (bs <= 0) bs = 1;
52: stash->bs = bs;
53: stash->nmax = 0;
54: stash->oldnmax = 0;
55: stash->n = 0;
56: stash->reallocs = -1;
57: stash->idx = 0;
58: stash->array = 0;
60: stash->send_waits = 0;
61: stash->recv_waits = 0;
62: stash->send_status = 0;
63: stash->nsends = 0;
64: stash->nrecvs = 0;
65: stash->svalues = 0;
66: stash->rvalues = 0;
67: stash->rmax = 0;
68: stash->nprocs = 0;
69: stash->nprocessed = 0;
70: stash->donotstash = PETSC_FALSE;
71: stash->ignorenegidx = PETSC_FALSE;
72: return(0);
73: }
75: /*
76: VecStashDestroy_Private - Destroy the stash
77: */
80: PetscErrorCode VecStashDestroy_Private(VecStash *stash)
81: {
85: PetscFree2(stash->array,stash->idx);
86: PetscFree(stash->bowners);
87: return(0);
88: }
90: /*
91: VecStashScatterEnd_Private - This is called as the fial stage of
92: scatter. The final stages of message passing is done here, and
93: all the memory used for message passing is cleanedu up. This
94: routine also resets the stash, and deallocates the memory used
95: for the stash. It also keeps track of the current memory usage
96: so that the same value can be used the next time through.
97: */
100: PetscErrorCode VecStashScatterEnd_Private(VecStash *stash)
101: {
103: PetscInt nsends=stash->nsends,oldnmax;
104: MPI_Status *send_status;
107: /* wait on sends */
108: if (nsends) {
109: PetscMalloc(2*nsends*sizeof(MPI_Status),&send_status);
110: MPI_Waitall(2*nsends,stash->send_waits,send_status);
111: PetscFree(send_status);
112: }
114: /* Now update nmaxold to be app 10% more than max n, this way the
115: wastage of space is reduced the next time this stash is used.
116: Also update the oldmax, only if it increases */
117: if (stash->n) {
118: oldnmax = ((PetscInt)(stash->n * 1.1) + 5)*stash->bs;
119: if (oldnmax > stash->oldnmax) stash->oldnmax = oldnmax;
120: }
122: stash->nmax = 0;
123: stash->n = 0;
124: stash->reallocs = -1;
125: stash->rmax = 0;
126: stash->nprocessed = 0;
128: PetscFree2(stash->array,stash->idx);
129: stash->array = 0;
130: stash->idx = 0;
131: PetscFree(stash->send_waits);
132: PetscFree(stash->recv_waits);
133: PetscFree2(stash->svalues,stash->sindices);
134: PetscFree2(stash->rvalues,stash->rindices);
135: PetscFree(stash->nprocs);
136: return(0);
137: }
139: /*
140: VecStashGetInfo_Private - Gets the relavant statistics of the stash
142: Input Parameters:
143: stash - the stash
144: nstash - the size of the stash
145: reallocs - the number of additional mallocs incurred.
146:
147: */
150: PetscErrorCode VecStashGetInfo_Private(VecStash *stash,PetscInt *nstash,PetscInt *reallocs)
151: {
154: if (nstash) *nstash = stash->n*stash->bs;
155: if (reallocs) {
156: if (stash->reallocs < 0) *reallocs = 0;
157: else *reallocs = stash->reallocs;
158: }
159: return(0);
160: }
163: /*
164: VecStashSetInitialSize_Private - Sets the initial size of the stash
166: Input Parameters:
167: stash - the stash
168: max - the value that is used as the max size of the stash.
169: this value is used while allocating memory. It specifies
170: the number of vals stored, even with the block-stash
171: */
174: PetscErrorCode VecStashSetInitialSize_Private(VecStash *stash,PetscInt max)
175: {
177: stash->umax = max;
178: return(0);
179: }
181: /* VecStashExpand_Private - Expand the stash. This function is called
182: when the space in the stash is not sufficient to add the new values
183: being inserted into the stash.
184:
185: Input Parameters:
186: stash - the stash
187: incr - the minimum increase requested
188:
189: Notes:
190: This routine doubles the currently used memory.
191: */
194: PetscErrorCode VecStashExpand_Private(VecStash *stash,PetscInt incr)
195: {
197: PetscInt *n_idx,newnmax,bs=stash->bs;
198: PetscScalar *n_array;
201: /* allocate a larger stash. */
202: if (!stash->oldnmax && !stash->nmax) { /* new stash */
203: if (stash->umax) newnmax = stash->umax/bs;
204: else newnmax = DEFAULT_STASH_SIZE/bs;
205: } else if (!stash->nmax) { /* resuing stash */
206: if (stash->umax > stash->oldnmax) newnmax = stash->umax/bs;
207: else newnmax = stash->oldnmax/bs;
208: } else newnmax = stash->nmax*2;
210: if (newnmax < (stash->nmax + incr)) newnmax += 2*incr;
212: PetscMalloc2(bs*newnmax,PetscScalar,&n_array,newnmax,PetscInt,&n_idx);
213: PetscMemcpy(n_array,stash->array,bs*stash->nmax*sizeof(PetscScalar));
214: PetscMemcpy(n_idx,stash->idx,stash->nmax*sizeof(PetscInt));
215: PetscFree2(stash->array,stash->idx);
216: stash->array = n_array;
217: stash->idx = n_idx;
218: stash->nmax = newnmax;
219: stash->reallocs++;
220: return(0);
221: }
222: /*
223: VecStashScatterBegin_Private - Initiates the transfer of values to the
224: correct owners. This function goes through the stash, and check the
225: owners of each stashed value, and sends the values off to the owner
226: processors.
228: Input Parameters:
229: stash - the stash
230: owners - an array of size 'no-of-procs' which gives the ownership range
231: for each node.
233: Notes: The 'owners' array in the cased of the blocked-stash has the
234: ranges specified blocked global indices, and for the regular stash in
235: the proper global indices.
236: */
239: PetscErrorCode VecStashScatterBegin_Private(VecStash *stash,PetscInt *owners)
240: {
242: PetscMPIInt size = stash->size,tag1=stash->tag1,tag2=stash->tag2;
243: PetscInt *owner,*start,*nprocs,nsends,nreceives;
244: PetscInt nmax,count,*sindices,*rindices,i,j,idx,bs=stash->bs,lastidx;
245: PetscScalar *rvalues,*svalues;
246: MPI_Comm comm = stash->comm;
247: MPI_Request *send_waits,*recv_waits;
251: /* first count number of contributors to each processor */
252: PetscMalloc(2*size*sizeof(PetscInt),&nprocs);
253: PetscMemzero(nprocs,2*size*sizeof(PetscInt));
254: PetscMalloc(stash->n*sizeof(PetscInt),&owner);
256: j = 0;
257: lastidx = -1;
258: for (i=0; i<stash->n; i++) {
259: /* if indices are NOT locally sorted, need to start search at the beginning */
260: if (lastidx > (idx = stash->idx[i])) j = 0;
261: lastidx = idx;
262: for (; j<size; j++) {
263: if (idx >= owners[j] && idx < owners[j+1]) {
264: nprocs[2*j]++; nprocs[2*j+1] = 1; owner[i] = j; break;
265: }
266: }
267: }
268: nsends = 0; for (i=0; i<size; i++) { nsends += nprocs[2*i+1];}
269:
270: /* inform other processors of number of messages and max length*/
271: PetscMaxSum(comm,nprocs,&nmax,&nreceives);
273: /* post receives:
274: since we don't know how long each individual message is we
275: allocate the largest needed buffer for each receive. Potentially
276: this is a lot of wasted space.
277: */
278: PetscMalloc2(nreceives*nmax*bs,PetscScalar,&rvalues,nreceives*nmax,PetscInt,&rindices);
279: PetscMalloc(2*nreceives*sizeof(MPI_Request),&recv_waits);
280: for (i=0,count=0; i<nreceives; i++) {
281: MPI_Irecv(rvalues+bs*nmax*i,bs*nmax,MPIU_SCALAR,MPI_ANY_SOURCE,tag1,comm,recv_waits+count++);
282: MPI_Irecv(rindices+nmax*i,nmax,MPIU_INT,MPI_ANY_SOURCE,tag2,comm,recv_waits+count++);
283: }
285: /* do sends:
286: 1) starts[i] gives the starting index in svalues for stuff going to
287: the ith processor
288: */
289: PetscMalloc2(stash->n*bs,PetscScalar,&svalues,stash->n,PetscInt,&sindices);
290: PetscMalloc(2*nsends*sizeof(MPI_Request),&send_waits);
291: PetscMalloc(size*sizeof(PetscInt),&start);
292: /* use 2 sends the first with all_v, the next with all_i */
293: start[0] = 0;
294: for (i=1; i<size; i++) {
295: start[i] = start[i-1] + nprocs[2*i-2];
296: }
297: for (i=0; i<stash->n; i++) {
298: j = owner[i];
299: if (bs == 1) {
300: svalues[start[j]] = stash->array[i];
301: } else {
302: PetscMemcpy(svalues+bs*start[j],stash->array+bs*i,bs*sizeof(PetscScalar));
303: }
304: sindices[start[j]] = stash->idx[i];
305: start[j]++;
306: }
307: start[0] = 0;
308: for (i=1; i<size; i++) { start[i] = start[i-1] + nprocs[2*i-2];}
309: for (i=0,count=0; i<size; i++) {
310: if (nprocs[2*i+1]) {
311: MPI_Isend(svalues+bs*start[i],bs*nprocs[2*i],MPIU_SCALAR,i,tag1,comm,send_waits+count++);
312: MPI_Isend(sindices+start[i],nprocs[2*i],MPIU_INT,i,tag2,comm,send_waits+count++);
313: }
314: }
315: PetscFree(owner);
316: PetscFree(start);
317: /* This memory is reused in scatter end for a different purpose*/
318: for (i=0; i<2*size; i++) nprocs[i] = -1;
319: stash->nprocs = nprocs;
321: stash->svalues = svalues;
322: stash->sindices = sindices;
323: stash->rvalues = rvalues;
324: stash->rindices = rindices;
325: stash->nsends = nsends;
326: stash->nrecvs = nreceives;
327: stash->send_waits = send_waits;
328: stash->recv_waits = recv_waits;
329: stash->rmax = nmax;
330: return(0);
331: }
333: /*
334: VecStashScatterGetMesg_Private - This function waits on the receives posted
335: in the function VecStashScatterBegin_Private() and returns one message at
336: a time to the calling function. If no messages are left, it indicates this
337: by setting flg = 0, else it sets flg = 1.
339: Input Parameters:
340: stash - the stash
342: Output Parameters:
343: nvals - the number of entries in the current message.
344: rows - an array of row indices (or blocked indices) corresponding to the values
345: cols - an array of columnindices (or blocked indices) corresponding to the values
346: vals - the values
347: flg - 0 indicates no more message left, and the current call has no values associated.
348: 1 indicates that the current call successfully received a message, and the
349: other output parameters nvals,rows,cols,vals are set appropriately.
350: */
353: PetscErrorCode VecStashScatterGetMesg_Private(VecStash *stash,PetscMPIInt *nvals,PetscInt **rows,PetscScalar **vals,PetscInt *flg)
354: {
356: PetscMPIInt i = 0; /* dummy value so MPI-Uni doesn't think it is not set */
357: PetscInt *flg_v;
358: PetscInt i1,i2,bs=stash->bs;
359: MPI_Status recv_status;
360: PetscBool match_found = PETSC_FALSE;
364: *flg = 0; /* When a message is discovered this is reset to 1 */
365: /* Return if no more messages to process */
366: if (stash->nprocessed == stash->nrecvs) { return(0); }
368: flg_v = stash->nprocs;
369: /* If a matching pair of receieves are found, process them, and return the data to
370: the calling function. Until then keep receiving messages */
371: while (!match_found) {
372: MPI_Waitany(2*stash->nrecvs,stash->recv_waits,&i,&recv_status);
373: /* Now pack the received message into a structure which is useable by others */
374: if (i % 2) {
375: MPI_Get_count(&recv_status,MPIU_INT,nvals);
376: flg_v[2*recv_status.MPI_SOURCE+1] = i/2;
377: } else {
378: MPI_Get_count(&recv_status,MPIU_SCALAR,nvals);
379: flg_v[2*recv_status.MPI_SOURCE] = i/2;
380: *nvals = *nvals/bs;
381: }
382:
383: /* Check if we have both the messages from this proc */
384: i1 = flg_v[2*recv_status.MPI_SOURCE];
385: i2 = flg_v[2*recv_status.MPI_SOURCE+1];
386: if (i1 != -1 && i2 != -1) {
387: *rows = stash->rindices + i2*stash->rmax;
388: *vals = stash->rvalues + i1*bs*stash->rmax;
389: *flg = 1;
390: stash->nprocessed ++;
391: match_found = PETSC_TRUE;
392: }
393: }
394: return(0);
395: }