cpu group pick_next函数
以下代码来自 pick_next_task_fair
6739 /*
6740 * Because of the set_next_buddy() in dequeue_task_fair() it is rather
6741 * likely that a next task is from the same cgroup as the current.
6742 *
6743 * Therefore attempt to avoid putting and setting the entire cgroup
6744 * hierarchy, only change the part that actually changes.
6745 */
6746
6747 do {
6748 struct sched_entity *curr = cfs_rq->curr;
6749
6750 /*
6751 * Since we got here without doing put_prev_entity() we also
6752 * have to consider cfs_rq->curr. If it is still a runnable
6753 * entity, update_curr() will update its vruntime, otherwise
6754 * forget we've ever seen it.
6755 */
6756 if (curr) {
6757 if (curr->on_rq)
6758 update_curr(cfs_rq);
6759 else
6760 curr = NULL;
6761
6762 /*
6763 * This call to check_cfs_rq_runtime() will do the
6764 * throttle and dequeue its entity in the parent(s).
6765 * Therefore the nr_running test will indeed
6766 * be correct.
6767 */
6768 if (unlikely(check_cfs_rq_runtime(cfs_rq))) {
6769 cfs_rq = &rq->cfs;
6770
6771 if (!cfs_rq->nr_running)
6772 goto idle;
6773
6774 goto simple;
6775 }
6776 }
6777
6778 **se = pick_next_entity(cfs_rq, curr);**
6779 **cfs_rq = group_cfs_rq(se);**
6780 } while (cfs_rq);
279 /* runqueue "owned" by this group */
280 static inline struct cfs_rq *group_cfs_rq(struct sched_entity *grp)
281 {
282 return grp->my_q;
283 }
1) 如果cpu 原始rq pick_next_entity选择的是非cgoup节点, 那么6779行返回空,即 my_q为空
2) 如果6778行选择的cgroup的根节点的sched_entity,那么会根据cgroup层次结构遍历一次遍历, 到最后的一层节点选出的sched_entity的my_q为空,则为真正的task entity
group share 计算
4.19 calc_group_shares