/*************************************************************************
* This function performs multilevel bisection
**************************************************************************/
void MlevelNodeBisection(CtrlType *ctrl, GraphType *graph, int *tpwgts, float ubfactor)
{
GraphType *cgraph;
ctrl->CoarsenTo = graph->nvtxs/8;
if (ctrl->CoarsenTo > 100)
ctrl->CoarsenTo = 100;
else if (ctrl->CoarsenTo < 40)
ctrl->CoarsenTo = 40;
ctrl->maxvwgt = 1.5*((tpwgts[0]+tpwgts[1])/ctrl->CoarsenTo);
cgraph = Coarsen2Way(ctrl, graph);
switch (ctrl->IType) {
case IPART_GGPKL:
Init2WayPartition(ctrl, cgraph, tpwgts, ubfactor);
IFSET(ctrl->dbglvl, DBG_TIME, starttimer(ctrl->SepTmr));
Compute2WayPartitionParams(ctrl, cgraph);
ConstructSeparator(ctrl, cgraph, ubfactor);
IFSET(ctrl->dbglvl, DBG_TIME, stoptimer(ctrl->SepTmr));
break;
case IPART_GGPKLNODE:
InitSeparator(ctrl, cgraph, ubfactor);
break;
}
Refine2WayNode(ctrl, graph, cgraph, ubfactor);
}
void MlevelNodeBisectionL2(ctrl_t *ctrl, graph_t *graph, idx_t niparts)
{
idx_t i, mincut, nruns=5;
graph_t *cgraph;
idx_t *bestwhere;
/* if the graph is small, just find a single vertex separator */
if (graph->nvtxs < 5000) {
MlevelNodeBisectionL1(ctrl, graph, niparts);
return;
}
WCOREPUSH;
ctrl->CoarsenTo = gk_max(100, graph->nvtxs/30);
cgraph = CoarsenGraphNlevels(ctrl, graph, 4);
bestwhere = iwspacemalloc(ctrl, cgraph->nvtxs);
mincut = graph->tvwgt[0];
for (i=0; i<nruns; i++) {
MlevelNodeBisectionL1(ctrl, cgraph, 0.7*niparts);
if (i == 0 || cgraph->mincut < mincut) {
mincut = cgraph->mincut;
if (i < nruns-1)
icopy(cgraph->nvtxs, cgraph->where, bestwhere);
}
if (mincut == 0)
break;
if (i < nruns-1)
FreeRData(cgraph);
}
if (mincut != cgraph->mincut)
icopy(cgraph->nvtxs, bestwhere, cgraph->where);
WCOREPOP;
Refine2WayNode(ctrl, graph, cgraph);
}
void MlevelNodeBisectionL1(ctrl_t *ctrl, graph_t *graph, idx_t niparts)
{
graph_t *cgraph;
ctrl->CoarsenTo = graph->nvtxs/8;
if (ctrl->CoarsenTo > 100)
ctrl->CoarsenTo = 100;
else if (ctrl->CoarsenTo < 40)
ctrl->CoarsenTo = 40;
cgraph = CoarsenGraph(ctrl, graph);
niparts = gk_max(1, (cgraph->nvtxs <= ctrl->CoarsenTo ? niparts/2: niparts));
/*niparts = (cgraph->nvtxs <= ctrl->CoarsenTo ? SMALLNIPARTS : LARGENIPARTS);*/
InitSeparator(ctrl, cgraph, niparts);
Refine2WayNode(ctrl, graph, cgraph);
}
/*************************************************************************
* This function performs multilevel bisection. It performs multiple
* bisections and selects the best.
**************************************************************************/
void MlevelNodeBisectionMultiple(CtrlType *ctrl, GraphType *graph, int *tpwgts, float ubfactor)
{
int i, nvtxs, cnvtxs, mincut, tmp;
GraphType *cgraph;
idxtype *bestwhere;
if (ctrl->nseps == 1 || graph->nvtxs < (ctrl->oflags&OFLAG_COMPRESS ? 1000 : 2000)) {
MlevelNodeBisection(ctrl, graph, tpwgts, ubfactor);
return;
}
nvtxs = graph->nvtxs;
if (ctrl->oflags&OFLAG_COMPRESS) { /* Multiple separators at the original graph */
bestwhere = idxmalloc(nvtxs, "MlevelNodeBisection2: bestwhere");
mincut = nvtxs;
for (i=ctrl->nseps; i>0; i--) {
MlevelNodeBisection(ctrl, graph, tpwgts, ubfactor);
/* printf("%5d ", cgraph->mincut); */
if (graph->mincut < mincut) {
mincut = graph->mincut;
idxcopy(nvtxs, graph->where, bestwhere);
}
GKfree(&graph->rdata, LTERM);
if (mincut == 0)
break;
}
/* printf("[%5d]\n", mincut); */
Allocate2WayNodePartitionMemory(ctrl, graph);
idxcopy(nvtxs, bestwhere, graph->where);
free(bestwhere);
Compute2WayNodePartitionParams(ctrl, graph);
}
else { /* Coarsen it a bit */
ctrl->CoarsenTo = nvtxs-1;
cgraph = Coarsen2Way(ctrl, graph);
cnvtxs = cgraph->nvtxs;
bestwhere = idxmalloc(cnvtxs, "MlevelNodeBisection2: bestwhere");
mincut = nvtxs;
for (i=ctrl->nseps; i>0; i--) {
ctrl->CType += 20; /* This is a hack. Look at coarsen.c */
MlevelNodeBisection(ctrl, cgraph, tpwgts, ubfactor);
/* printf("%5d ", cgraph->mincut); */
if (cgraph->mincut < mincut) {
mincut = cgraph->mincut;
idxcopy(cnvtxs, cgraph->where, bestwhere);
}
GKfree(&cgraph->rdata, LTERM);
if (mincut == 0)
break;
}
/* printf("[%5d]\n", mincut); */
Allocate2WayNodePartitionMemory(ctrl, cgraph);
idxcopy(cnvtxs, bestwhere, cgraph->where);
free(bestwhere);
Compute2WayNodePartitionParams(ctrl, cgraph);
Refine2WayNode(ctrl, graph, cgraph, ubfactor);
}
}
