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Annotation of /pkg/src/Metis/balance.c

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1 : bates 10 /*
2 :     * Copyright 1997, Regents of the University of Minnesota
3 :     *
4 :     * balance.c
5 :     *
6 :     * This file contains code that is used to forcefully balance either
7 :     * bisections or k-sections
8 :     *
9 :     * Started 7/29/97
10 :     * George
11 :     *
12 :     * $Id: balance.c,v 1.1 2003/12/31 21:32:30 bates Exp $
13 :     *
14 :     */
15 :    
16 :     #include <metis.h>
17 :    
18 :     /*************************************************************************
19 :     * This function is the entry point of the bisection balancing algorithms.
20 :     **************************************************************************/
21 :     void Balance2Way(CtrlType *ctrl, GraphType *graph, int *tpwgts, float ubfactor)
22 :     {
23 :     int i, j, nvtxs, from, imax, gain, mindiff;
24 :     idxtype *id, *ed;
25 :    
26 :     /* Return right away if the balance is OK */
27 :     mindiff = abs(tpwgts[0]-graph->pwgts[0]);
28 :     if (mindiff < 3*(graph->pwgts[0]+graph->pwgts[1])/graph->nvtxs)
29 :     return;
30 :     if (graph->pwgts[0] > tpwgts[0] && graph->pwgts[0] < (int)(ubfactor*tpwgts[0]))
31 :     return;
32 :     if (graph->pwgts[1] > tpwgts[1] && graph->pwgts[1] < (int)(ubfactor*tpwgts[1]))
33 :     return;
34 :    
35 :     if (graph->nbnd > 0)
36 :     Bnd2WayBalance(ctrl, graph, tpwgts);
37 :     else
38 :     General2WayBalance(ctrl, graph, tpwgts);
39 :    
40 :     }
41 :    
42 :    
43 :    
44 :     /*************************************************************************
45 :     * This function balances two partitions by moving boundary nodes
46 :     * from the domain that is overweight to the one that is underweight.
47 :     **************************************************************************/
48 :     void Bnd2WayBalance(CtrlType *ctrl, GraphType *graph, int *tpwgts)
49 :     {
50 :     int i, ii, j, k, kwgt, nvtxs, nbnd, nswaps, from, to, pass, me, tmp;
51 :     idxtype *xadj, *vwgt, *adjncy, *adjwgt, *where, *id, *ed, *bndptr, *bndind, *pwgts;
52 :     idxtype *moved, *perm;
53 :     PQueueType parts;
54 :     int higain, oldgain, mincut, mindiff;
55 :    
56 :     nvtxs = graph->nvtxs;
57 :     xadj = graph->xadj;
58 :     vwgt = graph->vwgt;
59 :     adjncy = graph->adjncy;
60 :     adjwgt = graph->adjwgt;
61 :     where = graph->where;
62 :     id = graph->id;
63 :     ed = graph->ed;
64 :     pwgts = graph->pwgts;
65 :     bndptr = graph->bndptr;
66 :     bndind = graph->bndind;
67 :    
68 :     moved = idxwspacemalloc(ctrl, nvtxs);
69 :     perm = idxwspacemalloc(ctrl, nvtxs);
70 :    
71 :     /* Determine from which domain you will be moving data */
72 :     mindiff = abs(tpwgts[0]-pwgts[0]);
73 :     from = (pwgts[0] < tpwgts[0] ? 1 : 0);
74 :     to = (from+1)%2;
75 :    
76 :     IFSET(ctrl->dbglvl, DBG_REFINE,
77 :     printf("Partitions: [%6d %6d] T[%6d %6d], Nv-Nb[%6d %6d]. ICut: %6d [B]\n",
78 :     pwgts[0], pwgts[1], tpwgts[0], tpwgts[1], graph->nvtxs, graph->nbnd, graph->mincut));
79 :    
80 :     tmp = graph->adjwgtsum[idxamax(nvtxs, graph->adjwgtsum)];
81 :     PQueueInit(ctrl, &parts, nvtxs, tmp);
82 :    
83 :     idxset(nvtxs, -1, moved);
84 :    
85 :     ASSERT(ComputeCut(graph, where) == graph->mincut);
86 :     ASSERT(CheckBnd(graph));
87 :    
88 :     /* Insert the boundary nodes of the proper partition whose size is OK in the priority queue */
89 :     nbnd = graph->nbnd;
90 :     RandomPermute(nbnd, perm, 1);
91 :     for (ii=0; ii<nbnd; ii++) {
92 :     i = perm[ii];
93 :     ASSERT(ed[bndind[i]] > 0 || id[bndind[i]] == 0);
94 :     ASSERT(bndptr[bndind[i]] != -1);
95 :     if (where[bndind[i]] == from && vwgt[bndind[i]] <= mindiff)
96 :     PQueueInsert(&parts, bndind[i], ed[bndind[i]]-id[bndind[i]]);
97 :     }
98 :    
99 :     mincut = graph->mincut;
100 :     for (nswaps=0; nswaps<nvtxs; nswaps++) {
101 :     if ((higain = PQueueGetMax(&parts)) == -1)
102 :     break;
103 :     ASSERT(bndptr[higain] != -1);
104 :    
105 :     if (pwgts[to]+vwgt[higain] > tpwgts[to])
106 :     break;
107 :    
108 :     mincut -= (ed[higain]-id[higain]);
109 :     INC_DEC(pwgts[to], pwgts[from], vwgt[higain]);
110 :    
111 :     where[higain] = to;
112 :     moved[higain] = nswaps;
113 :    
114 :     IFSET(ctrl->dbglvl, DBG_MOVEINFO,
115 :     printf("Moved %6d from %d. [%3d %3d] %5d [%4d %4d]\n", higain, from, ed[higain]-id[higain], vwgt[higain], mincut, pwgts[0], pwgts[1]));
116 :    
117 :     /**************************************************************
118 :     * Update the id[i]/ed[i] values of the affected nodes
119 :     ***************************************************************/
120 :     SWAP(id[higain], ed[higain], tmp);
121 :     if (ed[higain] == 0 && xadj[higain] < xadj[higain+1])
122 :     BNDDelete(nbnd, bndind, bndptr, higain);
123 :    
124 :     for (j=xadj[higain]; j<xadj[higain+1]; j++) {
125 :     k = adjncy[j];
126 :     oldgain = ed[k]-id[k];
127 :    
128 :     kwgt = (to == where[k] ? adjwgt[j] : -adjwgt[j]);
129 :     INC_DEC(id[k], ed[k], kwgt);
130 :    
131 :     /* Update its boundary information and queue position */
132 :     if (bndptr[k] != -1) { /* If k was a boundary vertex */
133 :     if (ed[k] == 0) { /* Not a boundary vertex any more */
134 :     BNDDelete(nbnd, bndind, bndptr, k);
135 :     if (moved[k] == -1 && where[k] == from && vwgt[k] <= mindiff) /* Remove it if in the queues */
136 :     PQueueDelete(&parts, k, oldgain);
137 :     }
138 :     else { /* If it has not been moved, update its position in the queue */
139 :     if (moved[k] == -1 && where[k] == from && vwgt[k] <= mindiff)
140 :     PQueueUpdate(&parts, k, oldgain, ed[k]-id[k]);
141 :     }
142 :     }
143 :     else {
144 :     if (ed[k] > 0) { /* It will now become a boundary vertex */
145 :     BNDInsert(nbnd, bndind, bndptr, k);
146 :     if (moved[k] == -1 && where[k] == from && vwgt[k] <= mindiff)
147 :     PQueueInsert(&parts, k, ed[k]-id[k]);
148 :     }
149 :     }
150 :     }
151 :     }
152 :    
153 :     IFSET(ctrl->dbglvl, DBG_REFINE,
154 :     printf("\tMinimum cut: %6d, PWGTS: [%6d %6d], NBND: %6d\n", mincut, pwgts[0], pwgts[1], nbnd));
155 :    
156 :     graph->mincut = mincut;
157 :     graph->nbnd = nbnd;
158 :    
159 :     PQueueFree(ctrl, &parts);
160 :    
161 :     idxwspacefree(ctrl, nvtxs);
162 :     idxwspacefree(ctrl, nvtxs);
163 :     }
164 :    
165 :    
166 :     /*************************************************************************
167 :     * This function balances two partitions by moving the highest gain
168 :     * (including negative gain) vertices to the other domain.
169 :     * It is used only when tha unbalance is due to non contigous
170 :     * subdomains. That is, the are no boundary vertices.
171 :     * It moves vertices from the domain that is overweight to the one that
172 :     * is underweight.
173 :     **************************************************************************/
174 :     void General2WayBalance(CtrlType *ctrl, GraphType *graph, int *tpwgts)
175 :     {
176 :     int i, ii, j, k, kwgt, nvtxs, nbnd, nswaps, from, to, pass, me, tmp;
177 :     idxtype *xadj, *vwgt, *adjncy, *adjwgt, *where, *id, *ed, *bndptr, *bndind, *pwgts;
178 :     idxtype *moved, *perm;
179 :     PQueueType parts;
180 :     int higain, oldgain, mincut, mindiff;
181 :    
182 :     nvtxs = graph->nvtxs;
183 :     xadj = graph->xadj;
184 :     vwgt = graph->vwgt;
185 :     adjncy = graph->adjncy;
186 :     adjwgt = graph->adjwgt;
187 :     where = graph->where;
188 :     id = graph->id;
189 :     ed = graph->ed;
190 :     pwgts = graph->pwgts;
191 :     bndptr = graph->bndptr;
192 :     bndind = graph->bndind;
193 :    
194 :     moved = idxwspacemalloc(ctrl, nvtxs);
195 :     perm = idxwspacemalloc(ctrl, nvtxs);
196 :    
197 :     /* Determine from which domain you will be moving data */
198 :     mindiff = abs(tpwgts[0]-pwgts[0]);
199 :     from = (pwgts[0] < tpwgts[0] ? 1 : 0);
200 :     to = (from+1)%2;
201 :    
202 :     IFSET(ctrl->dbglvl, DBG_REFINE,
203 :     printf("Partitions: [%6d %6d] T[%6d %6d], Nv-Nb[%6d %6d]. ICut: %6d [B]\n",
204 :     pwgts[0], pwgts[1], tpwgts[0], tpwgts[1], graph->nvtxs, graph->nbnd, graph->mincut));
205 :    
206 :     tmp = graph->adjwgtsum[idxamax(nvtxs, graph->adjwgtsum)];
207 :     PQueueInit(ctrl, &parts, nvtxs, tmp);
208 :    
209 :     idxset(nvtxs, -1, moved);
210 :    
211 :     ASSERT(ComputeCut(graph, where) == graph->mincut);
212 :     ASSERT(CheckBnd(graph));
213 :    
214 :     /* Insert the nodes of the proper partition whose size is OK in the priority queue */
215 :     RandomPermute(nvtxs, perm, 1);
216 :     for (ii=0; ii<nvtxs; ii++) {
217 :     i = perm[ii];
218 :     if (where[i] == from && vwgt[i] <= mindiff)
219 :     PQueueInsert(&parts, i, ed[i]-id[i]);
220 :     }
221 :    
222 :     mincut = graph->mincut;
223 :     nbnd = graph->nbnd;
224 :     for (nswaps=0; nswaps<nvtxs; nswaps++) {
225 :     if ((higain = PQueueGetMax(&parts)) == -1)
226 :     break;
227 :    
228 :     if (pwgts[to]+vwgt[higain] > tpwgts[to])
229 :     break;
230 :    
231 :     mincut -= (ed[higain]-id[higain]);
232 :     INC_DEC(pwgts[to], pwgts[from], vwgt[higain]);
233 :    
234 :     where[higain] = to;
235 :     moved[higain] = nswaps;
236 :    
237 :     IFSET(ctrl->dbglvl, DBG_MOVEINFO,
238 :     printf("Moved %6d from %d. [%3d %3d] %5d [%4d %4d]\n", higain, from, ed[higain]-id[higain], vwgt[higain], mincut, pwgts[0], pwgts[1]));
239 :    
240 :     /**************************************************************
241 :     * Update the id[i]/ed[i] values of the affected nodes
242 :     ***************************************************************/
243 :     SWAP(id[higain], ed[higain], tmp);
244 :     if (ed[higain] == 0 && bndptr[higain] != -1 && xadj[higain] < xadj[higain+1])
245 :     BNDDelete(nbnd, bndind, bndptr, higain);
246 :     if (ed[higain] > 0 && bndptr[higain] == -1)
247 :     BNDInsert(nbnd, bndind, bndptr, higain);
248 :    
249 :     for (j=xadj[higain]; j<xadj[higain+1]; j++) {
250 :     k = adjncy[j];
251 :     oldgain = ed[k]-id[k];
252 :    
253 :     kwgt = (to == where[k] ? adjwgt[j] : -adjwgt[j]);
254 :     INC_DEC(id[k], ed[k], kwgt);
255 :    
256 :     /* Update the queue position */
257 :     if (moved[k] == -1 && where[k] == from && vwgt[k] <= mindiff)
258 :     PQueueUpdate(&parts, k, oldgain, ed[k]-id[k]);
259 :    
260 :     /* Update its boundary information */
261 :     if (ed[k] == 0 && bndptr[k] != -1)
262 :     BNDDelete(nbnd, bndind, bndptr, k);
263 :     else if (ed[k] > 0 && bndptr[k] == -1)
264 :     BNDInsert(nbnd, bndind, bndptr, k);
265 :     }
266 :     }
267 :    
268 :     IFSET(ctrl->dbglvl, DBG_REFINE,
269 :     printf("\tMinimum cut: %6d, PWGTS: [%6d %6d], NBND: %6d\n", mincut, pwgts[0], pwgts[1], nbnd));
270 :    
271 :     graph->mincut = mincut;
272 :     graph->nbnd = nbnd;
273 :    
274 :     PQueueFree(ctrl, &parts);
275 :    
276 :     idxwspacefree(ctrl, nvtxs);
277 :     idxwspacefree(ctrl, nvtxs);
278 :     }

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