linux-kernel - [PATCH 15/15] sched,fair: remove se->depth

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Message-Id: <20190906191237.27006-16-riel@surriel.com>
Date:   Fri,  6 Sep 2019 15:12:37 -0400
From:   Rik van Riel <riel@...riel.com>
To:     linux-kernel@...r.kernel.org
Cc:     kernel-team@...com, pjt@...gle.com, dietmar.eggemann@....com,
        peterz@...radead.org, mingo@...hat.com, morten.rasmussen@....com,
        tglx@...utronix.de, mgorman@...hsingularity.net,
        vincent.guittot@...aro.org, Rik van Riel <riel@...riel.com>
Subject: [PATCH 15/15] sched,fair: remove se->depth

Remove se->depth and the code that touches it, since we no longer need
any of that.

Signed-off-by: Rik van Riel <riel@...riel.com>
Suggested-by: Dietmar Eggemann <dietmar.eggemann@....com>
---
 include/linux/sched.h |  1 -
 kernel/sched/fair.c   | 50 ++-----------------------------------------
 2 files changed, 2 insertions(+), 49 deletions(-)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index bdca15b3afe7..94aec4065fd1 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -451,7 +451,6 @@ struct sched_entity {
 	struct sched_statistics		statistics;
 
 #ifdef CONFIG_FAIR_GROUP_SCHED
-	int				depth;
 	unsigned long			enqueued_h_load;
 	unsigned long			enqueued_h_weight;
 	u64				propagated_exec_runtime;
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 3c25ab666799..0fb3de853d45 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -438,38 +438,6 @@ static inline bool task_se_in_cgroup(struct sched_entity *se)
 	return parent_entity(se);
 }
 
-static void
-find_matching_se(struct sched_entity **se, struct sched_entity **pse)
-{
-	int se_depth, pse_depth;
-
-	/*
-	 * preemption test can be made between sibling entities who are in the
-	 * same cfs_rq i.e who have a common parent. Walk up the hierarchy of
-	 * both tasks until we find their ancestors who are siblings of common
-	 * parent.
-	 */
-
-	/* First walk up until both entities are at same depth */
-	se_depth = (*se)->depth;
-	pse_depth = (*pse)->depth;
-
-	while (se_depth > pse_depth) {
-		se_depth--;
-		*se = parent_entity(*se);
-	}
-
-	while (pse_depth > se_depth) {
-		pse_depth--;
-		*pse = parent_entity(*pse);
-	}
-
-	while (!is_same_group(*se, *pse)) {
-		*se = parent_entity(*se);
-		*pse = parent_entity(*pse);
-	}
-}
-
 /* Add the cgroup cfs_rqs to the list, for update_blocked_averages */
 static void enqueue_entity_cfs_rqs(struct sched_entity *se)
 {
@@ -10221,14 +10189,6 @@ static void attach_entity_cfs_rq(struct sched_entity *se)
 	int flags = sched_feat(ATTACH_AGE_LOAD) ? 0 : SKIP_AGE_LOAD;
 	struct cfs_rq *cfs_rq = group_cfs_rq_of_parent(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, flags);
 	attach_entity_load_avg(cfs_rq, se, 0);
@@ -10316,10 +10276,7 @@ void init_cfs_rq(struct cfs_rq *cfs_rq)
 #ifdef CONFIG_FAIR_GROUP_SCHED
 static void task_set_group_fair(struct task_struct *p)
 {
-	struct sched_entity *se = &p->se;
-
 	set_task_rq(p, task_cpu(p));
-	se->depth = se->parent ? se->parent->depth + 1 : 0;
 }
 
 static void task_move_group_fair(struct task_struct *p)
@@ -10465,13 +10422,10 @@ void init_tg_cfs_entry(struct task_group *tg, struct cfs_rq *cfs_rq,
 	if (!se)
 		return;
 
-	if (!parent) {
+	if (!parent)
 		se->cfs_rq = &rq->cfs;
-		se->depth = 0;
-	} else {
+	else
 		se->cfs_rq = parent->my_q;
-		se->depth = parent->depth + 1;
-	}
 
 	se->my_q = cfs_rq;
 	/* guarantee group entities always have weight */
-- 
2.20.1