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From:   Chengming Zhou <zhouchengming@bytedance.com>
To:     mingo@redhat.com, peterz@infradead.org, vincent.guittot@linaro.org,
        dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com,
        vschneid@redhat.com
Cc:     linux-kernel@vger.kernel.org,
        Chengming Zhou <zhouchengming@bytedance.com>
Subject: [PATCH v2 03/10] sched/fair: maintain task se depth in set_task_rq()
Date:   Wed, 13 Jul 2022 12:04:23 +0800
Message-Id: <20220713040430.25778-4-zhouchengming@bytedance.com>
In-Reply-To: <20220713040430.25778-1-zhouchengming@bytedance.com>
References: <20220713040430.25778-1-zhouchengming@bytedance.com>
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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.

This patch move task se depth maintainence 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>
---
 kernel/sched/fair.c  | 8 --------
 kernel/sched/sched.h | 1 +
 2 files changed, 1 insertion(+), 8 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 2a3e12ead144..bf595b622656 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -11539,14 +11539,6 @@ 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 aad7f5ee9666..8cc3eb7b86cd 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -1940,6 +1940,7 @@ 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
-- 
2.36.1