/*
* Copyright 1997, Regents of the University of Minnesota
*
* minitpart.c
*
* This file contains code that performs the initial partition of the
* coarsest graph
*
* Started 7/23/97
* George
*
* $Id: minitpart.c,v 1.2 1998/11/30 15:08:37 karypis Exp $
*
*/
#include <metis.h>
/*************************************************************************
* This function computes the initial bisection of the coarsest graph
**************************************************************************/
void MocInit2WayPartition(CtrlType *ctrl, GraphType *graph, float *tpwgts, float ubfactor)
{
long i, dbglvl;
dbglvl = ctrl->dbglvl;
IFSET(ctrl->dbglvl, DBG_REFINE, ctrl->dbglvl -= DBG_REFINE);
IFSET(ctrl->dbglvl, DBG_MOVEINFO, ctrl->dbglvl -= DBG_MOVEINFO);
IFSET(ctrl->dbglvl, DBG_TIME, starttimer(ctrl->InitPartTmr));
switch (ctrl->IType) {
case IPART_GGPKL:
MocGrowBisection(ctrl, graph, tpwgts, ubfactor);
break;
case IPART_RANDOM:
MocRandomBisection(ctrl, graph, tpwgts, ubfactor);
break;
default:
errexit("Unknown initial partition type: %ld\n", ctrl->IType);
}
IFSET(ctrl->dbglvl, DBG_IPART, printf("Initial Cut: %ld [%ld]\n", graph->mincut, graph->where[0]));
IFSET(ctrl->dbglvl, DBG_TIME, stoptimer(ctrl->InitPartTmr));
ctrl->dbglvl = dbglvl;
}
/*************************************************************************
* This function takes a graph and produces a bisection by using a region
* growing algorithm. The resulting partition is returned in
* graph->where
**************************************************************************/
void MocGrowBisection(CtrlType *ctrl, GraphType *graph, float *tpwgts, float ubfactor)
{
long i, j, k, nvtxs, ncon, from, bestcut, mincut, nbfs;
idxtype *bestwhere, *where;
nvtxs = graph->nvtxs;
MocAllocate2WayPartitionMemory(ctrl, graph);
where = graph->where;
bestwhere = idxmalloc(nvtxs, "BisectGraph: bestwhere");
nbfs = 2*(nvtxs <= ctrl->CoarsenTo ? SMALLNIPARTS : LARGENIPARTS);
bestcut = idxsum(graph->nedges, graph->adjwgt);
for (; nbfs>0; nbfs--) {
idxset(nvtxs, 1, where);
where[RandomInRange(nvtxs)] = 0;
MocCompute2WayPartitionParams(ctrl, graph);
MocInit2WayBalance(ctrl, graph, tpwgts);
MocFM_2WayEdgeRefine(ctrl, graph, tpwgts, 4);
MocBalance2Way(ctrl, graph, tpwgts, 1.02);
MocFM_2WayEdgeRefine(ctrl, graph, tpwgts, 4);
if (bestcut >= graph->mincut) {
bestcut = graph->mincut;
idxcopy(nvtxs, where, bestwhere);
if (bestcut == 0)
break;
}
}
graph->mincut = bestcut;
idxcopy(nvtxs, bestwhere, where);
GKfree(&bestwhere, LTERM);
}
/*************************************************************************
* This function takes a graph and produces a bisection by using a region
* growing algorithm. The resulting partition is returned in
* graph->where
**************************************************************************/
void MocRandomBisection(CtrlType *ctrl, GraphType *graph, float *tpwgts, float ubfactor)
{
long i, ii, j, k, nvtxs, ncon, from, bestcut, mincut, nbfs, qnum;
idxtype *bestwhere, *where, *perm;
long counts[MAXNCON];
float *nvwgt;
nvtxs = graph->nvtxs;
ncon = graph->ncon;
nvwgt = graph->nvwgt;
MocAllocate2WayPartitionMemory(ctrl, graph);
where = graph->where;
bestwhere = idxmalloc(nvtxs, "BisectGraph: bestwhere");
nbfs = 2*(nvtxs <= ctrl->CoarsenTo ? SMALLNIPARTS : LARGENIPARTS);
bestcut = idxsum(graph->nedges, graph->adjwgt);
perm = idxmalloc(nvtxs, "BisectGraph: perm");
for (; nbfs>0; nbfs--) {
for (i=0; i<ncon; i++)
counts[i] = 0;
RandomPermute(nvtxs, perm, 1);
/* Partition by spliting the queues randomly */
for (ii=0; ii<nvtxs; ii++) {
i = perm[ii];
qnum = samax(ncon, nvwgt+i*ncon);
where[i] = counts[qnum];
counts[qnum] = (counts[qnum]+1)%2;
}
MocCompute2WayPartitionParams(ctrl, graph);
MocFM_2WayEdgeRefine(ctrl, graph, tpwgts, 6);
MocBalance2Way(ctrl, graph, tpwgts, 1.02);
MocFM_2WayEdgeRefine(ctrl, graph, tpwgts, 6);
MocBalance2Way(ctrl, graph, tpwgts, 1.02);
MocFM_2WayEdgeRefine(ctrl, graph, tpwgts, 6);
/*
printf("Edgecut: %6ld, NPwgts: [", graph->mincut);
for (i=0; i<graph->ncon; i++)
printf("(%.3f %.3f) ", graph->npwgts[i], graph->npwgts[graph->ncon+i]);
printf("]\n");
*/
if (bestcut >= graph->mincut) {
bestcut = graph->mincut;
idxcopy(nvtxs, where, bestwhere);
if (bestcut == 0)
break;
}
}
graph->mincut = bestcut;
idxcopy(nvtxs, bestwhere, where);
GKfree(&bestwhere, &perm, LTERM);
}
/*************************************************************************
* This function balances two partitions by moving the highest gain
* (including negative gain) vertices to the other domain.
* It is used only when tha unbalance is due to non contigous
* subdomains. That is, the are no boundary vertices.
* It moves vertices from the domain that is overweight to the one that
* is underweight.
**************************************************************************/
void MocInit2WayBalance(CtrlType *ctrl, GraphType *graph, float *tpwgts)
{
long SelectQueueOneWay(long , float *, float *, long , PQueueType[MAXNCON][2] ) ;
long i, ii, j, k, l, kwgt, nvtxs, nbnd, ncon, nswaps, from, to, pass, me, cnum, tmp;
idxtype *xadj, *adjncy, *adjwgt, *where, *id, *ed, *bndptr, *bndind;
idxtype *perm, *qnum;
float *nvwgt, *npwgts;
PQueueType parts[MAXNCON][2];
long higain, oldgain, mincut;
nvtxs = graph->nvtxs;
ncon = graph->ncon;
xadj = graph->xadj;
adjncy = graph->adjncy;
nvwgt = graph->nvwgt;
adjwgt = graph->adjwgt;
where = graph->where;
id = graph->id;
ed = graph->ed;
npwgts = graph->npwgts;
bndptr = graph->bndptr;
bndind = graph->bndind;
perm = idxwspacemalloc(ctrl, nvtxs);
qnum = idxwspacemalloc(ctrl, nvtxs);
/* This is called for initial partitioning so we know from where to pick nodes */
from = 1;
to = (from+1)%2;
if (ctrl->dbglvl&DBG_REFINE) {
printf("Parts: [");
for (l=0; l<ncon; l++)
printf("(%.3f, %.3f) ", npwgts[l], npwgts[ncon+l]);
printf("] T[%.3f %.3f], Nv-Nb[%5ld, %5ld]. ICut: %6ld, LB: %.3f [B]\n", tpwgts[0], tpwgts[1],
graph->nvtxs, graph->nbnd, graph->mincut,
Compute2WayHLoadImbalance(ncon, npwgts, tpwgts));
}
for (i=0; i<ncon; i++) {
PQueueInit(ctrl, &parts[i][0], nvtxs, PLUS_GAINSPAN+1);
PQueueInit(ctrl, &parts[i][1], nvtxs, PLUS_GAINSPAN+1);
}
ASSERT(ComputeCut(graph, where) == graph->mincut);
ASSERT(CheckBnd(graph));
ASSERT(CheckGraph(graph));
/* Compute the queues in which each vertex will be assigned to */
for (i=0; i<nvtxs; i++)
qnum[i] = samax(ncon, nvwgt+i*ncon);
/* Insert the nodes of the proper partition in the appropriate priority queue */
RandomPermute(nvtxs, perm, 1);
for (ii=0; ii<nvtxs; ii++) {
i = perm[ii];
if (where[i] == from) {
if (ed[i] > 0)
PQueueInsert(&parts[qnum[i]][0], i, ed[i]-id[i]);
else
PQueueInsert(&parts[qnum[i]][1], i, ed[i]-id[i]);
}
}
mincut = graph->mincut;
nbnd = graph->nbnd;
for (nswaps=0; nswaps<nvtxs; nswaps++) {
if (AreAnyVwgtsBelow(ncon, 1.0, npwgts+from*ncon, 0.0, nvwgt, tpwgts[from]))
break;
if ((cnum = SelectQueueOneWay(ncon, npwgts, tpwgts, from, parts)) == -1)
break;
if ((higain = PQueueGetMax(&parts[cnum][0])) == -1)
higain = PQueueGetMax(&parts[cnum][1]);
mincut -= (ed[higain]-id[higain]);
saxpy(ncon, 1.0, nvwgt+higain*ncon, 1, npwgts+to*ncon, 1);
saxpy(ncon, -1.0, nvwgt+higain*ncon, 1, npwgts+from*ncon, 1);
where[higain] = to;
if (ctrl->dbglvl&DBG_MOVEINFO) {
printf("Moved %6ld from %ld(%ld). [%5ld] %5ld, NPwgts: ", higain, from, cnum, ed[higain]-id[higain], mincut);
for (l=0; l<ncon; l++)
printf("(%.3f, %.3f) ", npwgts[l], npwgts[ncon+l]);
printf(", LB: %.3f\n", Compute2WayHLoadImbalance(ncon, npwgts, tpwgts));
if (ed[higain] == 0 && id[higain] > 0)
printf("\t Pulled from the interior!\n");
}
/**************************************************************
* Update the id[i]/ed[i] values of the affected nodes
***************************************************************/
SWAP(id[higain], ed[higain], tmp);
if (ed[higain] == 0 && bndptr[higain] != -1 && xadj[higain] < xadj[higain+1])
BNDDelete(nbnd, bndind, bndptr, higain);
if (ed[higain] > 0 && bndptr[higain] == -1)
BNDInsert(nbnd, bndind, bndptr, higain);
for (j=xadj[higain]; j<xadj[higain+1]; j++) {
k = adjncy[j];
oldgain = ed[k]-id[k];
kwgt = (to == where[k] ? adjwgt[j] : -adjwgt[j]);
INC_DEC(id[k], ed[k], kwgt);
/* Update the queue position */
if (where[k] == from) {
if (ed[k] > 0 && bndptr[k] == -1) { /* It moves in boundary */
PQueueDelete(&parts[qnum[k]][1], k, oldgain);
PQueueInsert(&parts[qnum[k]][0], k, ed[k]-id[k]);
}
else { /* It must be in the boundary already */
if (bndptr[k] == -1)
printf("What you thought was wrong!\n");
PQueueUpdate(&parts[qnum[k]][0], k, oldgain, ed[k]-id[k]);
}
}
/* Update its boundary information */
if (ed[k] == 0 && bndptr[k] != -1)
BNDDelete(nbnd, bndind, bndptr, k);
else if (ed[k] > 0 && bndptr[k] == -1)
BNDInsert(nbnd, bndind, bndptr, k);
}
ASSERTP(ComputeCut(graph, where) == mincut, ("%ld != %ld\n", ComputeCut(graph, where), mincut));
}
if (ctrl->dbglvl&DBG_REFINE) {
printf("\tMincut: %6ld, NBND: %6ld, NPwgts: ", mincut, nbnd);
for (l=0; l<ncon; l++)
printf("(%.3f, %.3f) ", npwgts[l], npwgts[ncon+l]);
printf(", LB: %.3f\n", Compute2WayHLoadImbalance(ncon, npwgts, tpwgts));
}
graph->mincut = mincut;
graph->nbnd = nbnd;
for (i=0; i<ncon; i++) {
PQueueFree(ctrl, &parts[i][0]);
PQueueFree(ctrl, &parts[i][1]);
}
ASSERT(ComputeCut(graph, where) == graph->mincut);
ASSERT(CheckBnd(graph));
idxwspacefree(ctrl, nvtxs);
idxwspacefree(ctrl, nvtxs);
}
/*************************************************************************
* This function selects the partition number and the queue from which
* we will move vertices out
**************************************************************************/
long SelectQueueOneWay(long ncon, float *npwgts, float *tpwgts, long from, PQueueType queues[MAXNCON][2])
{
long i, cnum=-1;
float max=0.0;
for (i=0; i<ncon; i++) {
if (npwgts[from*ncon+i]-tpwgts[from] >= max &&
PQueueGetSize(&queues[i][0]) + PQueueGetSize(&queues[i][1]) > 0) {
max = npwgts[from*ncon+i]-tpwgts[0];
cnum = i;
}
}
return cnum;
}
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