SD_task_schedule(taskA, 1, &hosts[0], &no_cost, &communication_amount1, -1.0);
SD_task_schedule(taskD, 1, &hosts[0], &no_cost, &communication_amount1, -1.0);
SD_task_schedule(taskA, 1, &hosts[0], &no_cost, &communication_amount1, -1.0);
SD_task_schedule(taskD, 1, &hosts[0], &no_cost, &communication_amount1, -1.0);