linux-kernel - Re: [PATCH 1/2][v2] sched: Make newidle

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Date:   Tue, 21 Apr 2020 09:17:50 +0200
From:   Vincent Guittot <vincent.guittot@...aro.org>
To:     Chen Yu <yu.c.chen@...el.com>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Juri Lelli <juri.lelli@...hat.com>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Ben Segall <bsegall@...gle.com>, Mel Gorman <mgorman@...e.de>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2][v2] sched: Make newidle_balance() static again

On Mon, 20 Apr 2020 at 17:01, Chen Yu <yu.c.chen@...el.com> wrote:
>
> After Commit 6e2df0581f56 ("sched: Fix pick_next_task() vs 'change'
> pattern race"), there is no need to expose newidle_balance() as it
> is only used within fair.c file. Change this function back to static again.
>
> No functional change.
>
> Suggested-by: Peter Zijlstra <peterz@...radead.org>
> Reported-by: kbuild test robot <lkp@...el.com>
> Signed-off-by: Chen Yu <yu.c.chen@...el.com>

Reviewed-by: Vincent Guittot <vincent.guittot@...aro.org>
> ---
> v2: Rename the remaining idle_balance() to newidle_balance()
>     to fix an compile error when CONFIG_SMP is not set.
> ---
>  kernel/sched/fair.c  | 6 ++++--
>  kernel/sched/sched.h | 4 ----
>  2 files changed, 4 insertions(+), 6 deletions(-)
>
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index 02f323b85b6d..cca5c9b7b5ae 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -3873,6 +3873,8 @@ static inline unsigned long cfs_rq_load_avg(struct cfs_rq *cfs_rq)
>         return cfs_rq->avg.load_avg;
>  }
>
> +static int newidle_balance(struct rq *this_rq, struct rq_flags *rf);
> +
>  static inline unsigned long task_util(struct task_struct *p)
>  {
>         return READ_ONCE(p->se.avg.util_avg);
> @@ -4054,7 +4056,7 @@ attach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) {}
>  static inline void
>  detach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) {}
>
> -static inline int idle_balance(struct rq *rq, struct rq_flags *rf)
> +static inline int newidle_balance(struct rq *rq, struct rq_flags *rf)
>  {
>         return 0;
>  }
> @@ -10425,7 +10427,7 @@ static inline void nohz_newidle_balance(struct rq *this_rq) { }
>   *     0 - failed, no new tasks
>   *   > 0 - success, new (fair) tasks present
>   */
> -int newidle_balance(struct rq *this_rq, struct rq_flags *rf)
> +static int newidle_balance(struct rq *this_rq, struct rq_flags *rf)
>  {
>         unsigned long next_balance = jiffies + HZ;
>         int this_cpu = this_rq->cpu;
> diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
> index db3a57675ccf..be83f88495fb 100644
> --- a/kernel/sched/sched.h
> +++ b/kernel/sched/sched.h
> @@ -1504,14 +1504,10 @@ static inline void unregister_sched_domain_sysctl(void)
>  }
>  #endif
>
> -extern int newidle_balance(struct rq *this_rq, struct rq_flags *rf);
> -
>  #else
>
>  static inline void sched_ttwu_pending(void) { }
>
> -static inline int newidle_balance(struct rq *this_rq, struct rq_flags *rf) { return 0; }
> -
>  #endif /* CONFIG_SMP */
>
>  #include "stats.h"
> --
> 2.17.1
>