On Tue, May 24, 2016 at 11:55:10AM +0200, Vincent Guittot wrote:
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index 218f8e8..6d3fbf2 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -290,15 +290,31 @@ static inline void list_add_leaf_cfs_rq(struct cfs_rq
> *cfs_rq)
> * Ensure we either appear before our parent (if already
> * enqueued) or force our parent to appear after us when it is
> * enqueued. The fact that we always enqueue bottom-up
> + * reduces this to two cases and a specila case for the root
'special'
> + * cfs_rq.
> */
> if (cfs_rq->tg->parent &&
> cfs_rq->tg->parent->cfs_rq[cpu_of(rq_of(cfs_rq))]->on_list)
> {
> + /* Add the child just before its parent */
> + list_add_tail_rcu(&cfs_rq->leaf_cfs_rq_list,
> +
> &(cfs_rq->tg->parent->cfs_rq[cpu_of(rq_of(cfs_rq))]->leaf_cfs_rq_list));
> + rq_of(cfs_rq)->leaf_alone =
> &rq_of(cfs_rq)->leaf_cfs_rq_list;
> + } else if (!cfs_rq->tg->parent) {
> + /*
> + * cfs_rq without parent should be
> + * at the end of the list
> + */
> list_add_tail_rcu(&cfs_rq->leaf_cfs_rq_list,
> &rq_of(cfs_rq)->leaf_cfs_rq_list);
> + rq_of(cfs_rq)->leaf_alone =
> &rq_of(cfs_rq)->leaf_cfs_rq_list;
> + } else {
> + /*
> + * Our parent has not already been added so make sure
> + * that it will be put after us
> + */
> + list_add_rcu(&cfs_rq->leaf_cfs_rq_list,
> + rq_of(cfs_rq)->leaf_alone);
> + rq_of(cfs_rq)->leaf_alone = &cfs_rq->leaf_cfs_rq_list;
> }
>
> cfs_rq->on_list = 1;
Paul, Ben ?
This used to be critical for update_shares() (now
update_blocked_averages), but IIRC is not critical for that since PELT.
I find its more readable with like so..
Also; I feel the comments can use more love; my head hurts ;-)
---
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -286,35 +286,38 @@ static inline struct cfs_rq *group_cfs_r
static inline void list_add_leaf_cfs_rq(struct cfs_rq *cfs_rq)
{
if (!cfs_rq->on_list) {
+ struct rq *rq = rq_of(cfs_rq);
+ int cpu = cpu_of(rq);
+
/*
* Ensure we either appear before our parent (if already
* enqueued) or force our parent to appear after us when it is
* enqueued. The fact that we always enqueue bottom-up
- * reduces this to two cases and a specila case for the root
+ * reduces this to two cases and a special case for the root
* cfs_rq.
*/
if (cfs_rq->tg->parent &&
- cfs_rq->tg->parent->cfs_rq[cpu_of(rq_of(cfs_rq))]->on_list)
{
+ cfs_rq->tg->parent->cfs_rq[cpu]->on_list) {
/* Add the child just before its parent */
list_add_tail_rcu(&cfs_rq->leaf_cfs_rq_list,
-
&(cfs_rq->tg->parent->cfs_rq[cpu_of(rq_of(cfs_rq))]->leaf_cfs_rq_list));
- rq_of(cfs_rq)->leaf_alone =
&rq_of(cfs_rq)->leaf_cfs_rq_list;
+
&(cfs_rq->tg->parent->cfs_rq[cpu]->leaf_cfs_rq_list));
+ rq->leaf_alone = &rq->leaf_cfs_rq_list;
} else if (!cfs_rq->tg->parent) {
/*
* cfs_rq without parent should be
* at the end of the list
*/
list_add_tail_rcu(&cfs_rq->leaf_cfs_rq_list,
- &rq_of(cfs_rq)->leaf_cfs_rq_list);
- rq_of(cfs_rq)->leaf_alone =
&rq_of(cfs_rq)->leaf_cfs_rq_list;
+ &rq->leaf_cfs_rq_list);
+ rq->leaf_alone = &rq->leaf_cfs_rq_list;
} else {
/*
* Our parent has not already been added so make sure
* that it will be put after us
*/
list_add_rcu(&cfs_rq->leaf_cfs_rq_list,
- rq_of(cfs_rq)->leaf_alone);
- rq_of(cfs_rq)->leaf_alone = &cfs_rq->leaf_cfs_rq_list;
+ rq->leaf_alone);
+ rq->leaf_alone = &cfs_rq->leaf_cfs_rq_list;
}
cfs_rq->on_list = 1;
