linux.conf.au, January 2003
      PROGRAMMING: kernel/sched.c

 	#define CAN_MIGRATE_TASK(p,rq,this_cpu)				\ 
 		((jiffies - (p)->sleep_timestamp > cache_decay_ticks) &&		\ 
 			!task_running(rq, p) &&				\ 
 				((p)->cpus_allowed & (1UL << (this_cpu))))
 	
 		curr = curr->prev;
 	
 		if (!CAN_MIGRATE_TASK(tmp, busiest, this_cpu)) {
 			if (curr != head)
 				goto skip_queue;
 			idx++;
 			goto skip_bitmap;
 		}
 		pull_task(busiest, array, tmp, this_rq, this_cpu);
 		if (!idle && --imbalance) {
 			if (curr != head)
 				goto skip_queue;
 			idx++;
 			goto skip_bitmap;
 		}
 	out_unlock:
 		spin_unlock(&busiest->lock);
 	out:
 		;
 	}