linux-kernel - [PATCH] sched/core: not necessary to init root_task

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Date:   Thu, 23 Apr 2020 21:44:43 +0000
From:   Wei Yang <richard.weiyang@...il.com>
To:     mingo@...hat.com, peterz@...radead.org
Cc:     linux-kernel@...r.kernel.org, Wei Yang <richard.weiyang@...il.com>
Subject: [PATCH] sched/core: not necessary to init root_task_group's common part for each cpu

Currently root_task_group.shares and cfs_bandwidth are initialized for
each online cpu, which not necessary.

Let's take it out to do it only once.

Signed-off-by: Wei Yang <richard.weiyang@...il.com>
---
 kernel/sched/core.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 5ca567adfcb9..613d6e892d80 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -6642,6 +6642,8 @@ void __init sched_init(void)
 		root_task_group.cfs_rq = (struct cfs_rq **)ptr;
 		ptr += nr_cpu_ids * sizeof(void **);
 
+		root_task_group.shares = ROOT_TASK_GROUP_LOAD;
+		init_cfs_bandwidth(&root_task_group.cfs_bandwidth);
 #endif /* CONFIG_FAIR_GROUP_SCHED */
 #ifdef CONFIG_RT_GROUP_SCHED
 		root_task_group.rt_se = (struct sched_rt_entity **)ptr;
@@ -6694,7 +6696,6 @@ void __init sched_init(void)
 		init_rt_rq(&rq->rt);
 		init_dl_rq(&rq->dl);
 #ifdef CONFIG_FAIR_GROUP_SCHED
-		root_task_group.shares = ROOT_TASK_GROUP_LOAD;
 		INIT_LIST_HEAD(&rq->leaf_cfs_rq_list);
 		rq->tmp_alone_branch = &rq->leaf_cfs_rq_list;
 		/*
@@ -6716,7 +6717,6 @@ void __init sched_init(void)
 		 * We achieve this by letting root_task_group's tasks sit
 		 * directly in rq->cfs (i.e root_task_group->se[] = NULL).
 		 */
-		init_cfs_bandwidth(&root_task_group.cfs_bandwidth);
 		init_tg_cfs_entry(&root_task_group, &rq->cfs, NULL, i, NULL);
 #endif /* CONFIG_FAIR_GROUP_SCHED */
 
-- 
2.23.0