GlobalAddress< void > global_pointer() {
return make_linear( memory_ );
}
ClampView() {
fGrad = make_linear();
}
void bfs(GlobalAddress<G> _g, int nbfs, TupleGraph tg) {
bool verified = false;
double t;
auto _frontier = GlobalBag<VertexID>::create(_g->nv);
auto _next = GlobalBag<VertexID>::create(_g->nv);
call_on_all_cores([=]{ frontier = _frontier; next = _next; g = _g; });
// do BFS from multiple different roots and average their times
for (int root_idx = 0; root_idx < nbfs; root_idx++) {
// intialize parent to -1
forall(g, [](G::Vertex& v){ v->init(); v->level = -1; });
VertexID root;
if (FLAGS_max_degree_source) {
forall(g, [](VertexID i, G::Vertex& v){
max_degree << MaxDegree(i, v.nadj);
});
root = static_cast<MaxDegree>(max_degree).idx();
} else {
root = choose_root(g);
}
// setup 'root' as the parent of itself
delegate::call(g->vs+root, [=](G::Vertex& v){
v->parent = root;
v->level = 0;
});
// reset frontier queues
next->clear();
frontier->clear();
// start with root as only thing in frontier
delegate::call((g->vs+root).core(), [=]{ frontier->add(root); });
t = walltime();
bool top_down = true;
int64_t prev_nf = -1;
int64_t frontier_edges = 0;
int64_t remaining_edges = g->nadj;
while (!frontier->empty()) {
auto nf = frontier->size();
VLOG(1) << "remaining_edges = " << remaining_edges << ", nf = " << nf << ", prev_nf = " << prev_nf << ", frontier_edges: " ;
if (top_down && frontier_edges > remaining_edges/FLAGS_beamer_alpha && nf > prev_nf) {
VLOG(1) << "switching to bottom-up";
top_down = false;
} else if (!top_down && frontier_edges < g->nv/FLAGS_beamer_beta && nf < prev_nf) {
VLOG(1) << "switching to top-down";
top_down = true;
}
edge_count = 0;
if (top_down) {
// iterate over vertices in this level of the frontier
forall(frontier, [](VertexID& i){
// visit all the adjacencies of the vertex
// note: this has to be 'async' to prevent deadlock from
// running out of available workers
forall<async>(adj(g,i), [i](G::Edge& e) {
auto j = e.id;
// at the core where the vertex is...
delegate::call<async>(e.ga, [i,j](G::Vertex& vj){
// note: no synchronization needed because 'call' is
// guaranteed to be executed atomically because it
// does no blocking operations
if (vj->parent == -1) {
// claim parenthood
vj->parent = i;
vj->level = current_depth;
next->add(j);
edge_count += vj.nadj;
}
});
});
});
} else { // bottom-up
forall<&phaser>(g, [](G::Vertex& v){
if (v->level != -1) return;
auto va = make_linear(&v);
forall<async,&phaser>(adj(g,v), [=,&v](G::Edge& e){
if (v->level != -1) return;
phaser.enroll();
auto eva = e.ga;
send_heap_message(eva.core(), [=]{
auto& ev = *eva.pointer();
if (ev->level != -1 && ev->level < current_depth) {
auto eid = g->id(ev);
send_heap_message(va.core(), [=]{
auto& v = *va.pointer();
if (v->level == -1) {
next->add(g->id(v));
v->level = current_depth;
v->parent = eid;
edge_count += v.nadj;
}
phaser.complete();
});
} else {
phaser.send_completion(va.core());
}
});
});
});
}
call_on_all_cores([=]{
current_depth++;
// switch to next frontier level
std::swap(frontier, next);
});
next->clear();
frontier_edges = edge_count;
remaining_edges -= frontier_edges;
prev_nf = nf;
} // while (frontier not empty)
double this_bfs_time = walltime() - t;
LOG(INFO) << "(root=" << root << ", time=" << this_bfs_time << ")";
if (!verified) {
// only verify the first one to save time
t = walltime();
bfs_nedge = verify(tg, g, root);
verify_time = (walltime()-t);
LOG(INFO) << verify_time;
verified = true;
Metrics::reset_all_cores(); // don't count the first one
} else {
total_time += this_bfs_time;
}
bfs_mteps += bfs_nedge / this_bfs_time / 1.0e6;
}
}
