run_conn_gc
ok = run_conn_gc(0, 0, 0);
ok = run_conn_gc(1, 0, 1);
ok = run_conn_gc(0, 1, 0);
ok = run_conn_gc(1, 1, 1);
ok = run_conn_gc(0, 2, 0);
ok = run_conn_gc(0, 128, 0);
ok = run_conn_gc(0, 512, 256);
ok = run_conn_gc(0, 512, 384);