linux-kernel - Re: [PATCH v2] sched: move cfs_bandwidth

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Date:   Thu, 10 Feb 2022 13:05:30 -0800
From:   Luis Chamberlain <mcgrof@...nel.org>
To:     Zhen Ni <nizhen@...ontech.com>
Cc:     mingo@...hat.com, peterz@...radead.org, juri.lelli@...hat.com,
        vincent.guittot@...aro.org, dietmar.eggemann@....com,
        rostedt@...dmis.org, bsegall@...gle.com, mgorman@...e.de,
        bristot@...hat.com, keescook@...omium.org, yzaikin@...gle.com,
        linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH v2] sched: move cfs_bandwidth_slice sysctls to fair.c

On Thu, Feb 10, 2022 at 01:40:28PM +0800, Zhen Ni wrote:
> move cfs_bandwidth_slice sysctls to fair.c and use the
> new register_sysctl_init() to register the sysctl interface.
> 
> Signed-off-by: Zhen Ni <nizhen@...ontech.com>
> ---

Your description of what has changed in your v2 should go here.
If a v3, then your v2 notes and v3 notes should be here as well.

>  include/linux/sched/sysctl.h |  4 ----
>  kernel/sched/fair.c          | 25 +++++++++++++++++++++++--
>  kernel/sysctl.c              | 10 ----------
>  3 files changed, 23 insertions(+), 16 deletions(-)
> 
> diff --git a/include/linux/sched/sysctl.h b/include/linux/sched/sysctl.h
> index c19dd5a2c05c..d416d8f45186 100644
> --- a/include/linux/sched/sysctl.h
> +++ b/include/linux/sched/sysctl.h
> @@ -41,10 +41,6 @@ extern unsigned int sysctl_sched_uclamp_util_max;
>  extern unsigned int sysctl_sched_uclamp_util_min_rt_default;
>  #endif
>  
> -#ifdef CONFIG_CFS_BANDWIDTH
> -extern unsigned int sysctl_sched_cfs_bandwidth_slice;
> -#endif
> -
>  #ifdef CONFIG_SCHED_AUTOGROUP
>  extern unsigned int sysctl_sched_autogroup_enabled;
>  #endif
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index 5146163bfabb..354ebf938567 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -141,8 +141,26 @@ int __weak arch_asym_cpu_priority(int cpu)
>   *
>   * (default: 5 msec, units: microseconds)
>   */
> -unsigned int sysctl_sched_cfs_bandwidth_slice		= 5000UL;
> -#endif
> +static unsigned int sysctl_sched_cfs_bandwidth_slice		= 5000UL;
> +#ifdef CONFIG_SYSCTL
> +static struct ctl_table sched_cfs_bandwidth_sysctls[] = {
> +	{
> +		.procname       = "sched_cfs_bandwidth_slice_us",
> +		.data           = &sysctl_sched_cfs_bandwidth_slice,
> +		.maxlen         = sizeof(unsigned int),
> +		.mode           = 0644,
> +		.proc_handler   = proc_dointvec_minmax,
> +		.extra1         = SYSCTL_ONE,
> +	},
> +	{}
> +};
> +
> +static void __init sched_cfs_bandwidth_sysctl_init(void)
> +{
> +	register_sysctl_init("kernel", sched_cfs_bandwidth_sysctls);
> +}
> +#endif /* CONFIG_SYSCTL */

Maybe an #else which then adds a no-op sched_cfs_bandwidth_sysctl_init

> +#endif /* CONFIG_CFS_BANDWIDTH */

Likewise, if disabled, then have a no-op sched_cfs_bandwidth_sysctl_init()

>  static inline void update_load_add(struct load_weight *lw, unsigned long inc)
>  {
> @@ -207,6 +225,9 @@ static void update_sysctl(void)
>  void __init sched_init_granularity(void)
>  {
>  	update_sysctl();
> +#if defined(CONFIG_CFS_BANDWIDTH) && defined(CONFIG_SYSCTL)
> +	sched_cfs_bandwidth_sysctl_init();
> +#endif

Then you can get remove the #ifdef mess from this code.

But this is a style issue nothing major.

  Luis