for (int i = 0; i < TASK_NUM; i++) {
task[i] = SD_task_create("Comm", NULL, 1.0);
SD_task_schedule(task[i], 2, hosts, no_cost, communication_amount, -1.0);
for (int i = 0; i < TASK_NUM; i++) {
task[i] = SD_task_create("Comm", NULL, 1.0);
SD_task_schedule(task[i], 2, hosts, no_cost, communication_amount, -1.0);