sched/fair: Maintain task se depth in set_task_rq()

Previously we only maintain task se depth in task_move_group_fair(),
if a !fair task change task group, its se depth will not be updated,
so commit eb7a59b2c888 ("sched/fair: Reset se-depth when task switched to FAIR")
fix the problem by updating se depth in switched_to_fair() too.

Then commit daa59407b558 ("sched/fair: Unify switched_{from,to}_fair()
and task_move_group_fair()") unified these two functions, moved se.depth
setting to attach_task_cfs_rq(), which further into attach_entity_cfs_rq()
with commit df217913e72e ("sched/fair: Factorize attach/detach entity").

This patch move task se depth maintenance from attach_entity_cfs_rq()
to set_task_rq(), which will be called when CPU/cgroup change, so its
depth will always be correct.

This patch is preparation for the next patch.

Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20220818124805.601-2-zhouchengming@bytedance.com

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index da388657d5ac3bd2628329438cfdc4f291dc1711..a3b0f8b1029e9f8a4dc59467113e888ceaf5a75a 100644 (file)
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -11562,14 +11562,6 @@ static void attach_entity_cfs_rq(struct sched_entity *se)
 {
        struct cfs_rq *cfs_rq = cfs_rq_of(se);
 
-#ifdef CONFIG_FAIR_GROUP_SCHED
-       /*
-        * Since the real-depth could have been changed (only FAIR
-        * class maintain depth value), reset depth properly.
-        */
-       se->depth = se->parent ? se->parent->depth + 1 : 0;
-#endif
-
        /* Synchronize entity with its cfs_rq */
        update_load_avg(cfs_rq, se, sched_feat(ATTACH_AGE_LOAD) ? 0 : SKIP_AGE_LOAD);
        attach_entity_load_avg(cfs_rq, se);

diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 3ccd35c22f0fd00b6f126a048af51cc378511a7a..4c4822141026e1e5527692d2c899cb643ed0adff 100644 (file)
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -1930,6 +1930,7 @@ static inline void set_task_rq(struct task_struct *p, unsigned int cpu)
        set_task_rq_fair(&p->se, p->se.cfs_rq, tg->cfs_rq[cpu]);
        p->se.cfs_rq = tg->cfs_rq[cpu];
        p->se.parent = tg->se[cpu];
+       p->se.depth = tg->se[cpu] ? tg->se[cpu]->depth + 1 : 0;
 #endif
 
 #ifdef CONFIG_RT_GROUP_SCHED