linux-kernel - [tip: sched/core] sched/fair: Fix cfs_rq_is

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Date:   Fri, 15 Sep 2023 12:26:59 -0000
From:   "tip-bot2 for Chengming Zhou" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     "Leo Yu-Chi Liang" <ycliang@...estech.com>,
        Chengming Zhou <zhouchengming@...edance.com>,
        Ingo Molnar <mingo@...nel.org>,
        Vincent Guittot <vincent.guittot@...aro.org>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: [tip: sched/core] sched/fair: Fix cfs_rq_is_decayed() on !SMP

The following commit has been merged into the sched/core branch of tip:

Commit-ID:     c0490bc9bb62d9376f3dd4ec28e03ca0fef97152
Gitweb:        https://git.kernel.org/tip/c0490bc9bb62d9376f3dd4ec28e03ca0fef97152
Author:        Chengming Zhou <zhouchengming@...edance.com>
AuthorDate:    Wed, 13 Sep 2023 13:20:31 
Committer:     Ingo Molnar <mingo@...nel.org>
CommitterDate: Fri, 15 Sep 2023 14:24:00 +02:00

sched/fair: Fix cfs_rq_is_decayed() on !SMP

We don't need to maintain per-queue leaf_cfs_rq_list on !SMP, since
it's used for cfs_rq load tracking & balancing on SMP.

But sched debug interface uses it to print per-cfs_rq stats.

This patch fixes the !SMP version of cfs_rq_is_decayed(), so the
per-queue leaf_cfs_rq_list is also maintained correctly on !SMP,
to fix the warning in assert_list_leaf_cfs_rq().

Fixes: 0a00a354644e ("sched/fair: Delete useless condition in tg_unthrottle_up()")
Reported-by: Leo Yu-Chi Liang <ycliang@...estech.com>
Signed-off-by: Chengming Zhou <zhouchengming@...edance.com>
Signed-off-by: Ingo Molnar <mingo@...nel.org>
Tested-by: Leo Yu-Chi Liang <ycliang@...estech.com>
Reviewed-by: Vincent Guittot <vincent.guittot@...aro.org>
Closes: https://lore.kernel.org/all/ZN87UsqkWcFLDxea@swlinux02/
Link: https://lore.kernel.org/r/20230913132031.2242151-1-chengming.zhou@linux.dev
---
 kernel/sched/fair.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 41cfd61..c893721 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -4866,7 +4866,7 @@ static inline void update_misfit_status(struct task_struct *p, struct rq *rq)
 
 static inline bool cfs_rq_is_decayed(struct cfs_rq *cfs_rq)
 {
-	return true;
+	return !cfs_rq->nr_running;
 }
 
 #define UPDATE_TG	0x0