【内核调度、负载均衡】【find_busiest_queue】

在最繁忙的group中去寻找最繁忙的cpu

find_busiest_queue

/*
 * find_busiest_queue - find the busiest runqueue among the cpus in group.
 */
 //冒泡排序找到group内最忙的rq
static struct rq *find_busiest_queue(struct lb_env *env,
				     struct sched_group *group)
{
	struct rq *busiest = NULL, *rq;
	unsigned long busiest_load = 0, busiest_capacity = 1;
	int i;
	
	//冒泡排序遍历group内最忙的cpu
	for_each_cpu_and(i, sched_group_span(group), env->cpus) {
		unsigned long capacity, wl;
		enum fbq_type rt;

		rq = cpu_rq(i);
		rt = fbq_classify_rq(rq);

		/*
		 * We classify groups/runqueues into three groups:
		 *  - regular: there are !numa tasks
		 *  - remote:  there are numa tasks that run on the 'wrong' node
		 *  - all:     there is no distinction
		 *
		 * In order to avoid migrating ideally placed numa tasks,
		 * ignore those when there's better options.
		 *
		 * If we ignore the actual busiest queue to migrate another
		 * task, the next balance pass can still reduce the busiest
		 * q